## 1. Theorizing Ethical Supervenience



Many philosophers hope to make significant arguments about ethics
using ethical supervenience as a premise. However, there are many
distinct ethical supervenience theses that philosophers might be
interested in. Understanding the differences between these theses can
help to clarify which of them deserve our allegiance. It is also
important because different supervenience theses will support quite
different arguments about ethics.



To begin, it is worth briefly characterizing certain core features of
supervenience relations, as they are now standardly understood in
metaphysics (see, e.g., the entry on
 supervenience).
 Supervenience relations are typically understood as relations between
pairs of classes of properties. Consider the claim that a certain
class of properties--the *A*-properties--cannot vary
without the *B*-properties also varying. In this claim, we can
call the *A*-properties the *supervening* properties,
and the *B*-properties the *subvening* or *base*
properties.



Supervenience relations are *covariance* relations that have
three logical features: they are reflexive, transitive, and
non-symmetric. The claim that supervenience is *reflexive*
means that every set of properties supervenes on itself: for any class
of properties *A*, there can be no difference in the
*A*-properties without a difference in the
*A*-properties. The claim that supervenience is
*transitive* means that: if the *A*-properties supervene
on the *B*-properties, and the *B*-properties supervene
on the *C*-properties, then the *A*-properties supervene
on the *C*-properties. The claim that supervenience is
*non-symmetric* means that supervenience is compatible with
either symmetry (*A* supervenes on *B* and *B*
supervenes on *A*; as in the case of the ethical and itself) or
asymmetry (*A* supervenes on *B* but *B* does not
supervene on *A*; as may be the case between the biological and
the microphysical).



These claims reflect how use of the word 'supervenience'
has come to be usefully regimented in contemporary metaphysics. It is
worth emphasizing this point, because there is a significant history
of the word being used in ways that depart from this contemporary
orthodoxy. For example, for a time it was quite common both in
metaphysics and in ethics for 'supervenience' to be used
to mark an asymmetrical dependence relation. Such uses are, however,
inconsistent with the contemporary regimentation. This is a point
about terminological clarity, not a substantive barrier to discussing
such asymmetric relations. For example, one could name the asymmetric
relation that holds when *A* supervenes on *B* but
*B* does not supervene on *A*. Or one could name the
relation that holds when the supervenience of *A* on *B*
is accompanied by an adequate explanation. One influential variant of
the latter sort of explanatory relation has been dubbed
'superdupervenience' (Horgan 1993, 566). More recently,
many philosophers have suggested that a certain asymmetric dependence
relation--*grounding*--is of central importance to
our metaphysical theorizing. (For discussion, see the entry on
 metaphysical grounding.)



Given the standard contemporary regimentation, however, supervenience
claims *state* a certain pattern of covariation between classes
of properties, they do not purport to *explain* that pattern,
as a grounding or superdupervenience thesis would (compare DePaul
1987). This point is crucial to several arguments from ethical
supervenience, as we will see below.



These clarifying remarks put us in a position to introduce four
central questions that can be used to develop alternative
supervenience theses:


* How can we best characterize which properties the ethical
properties supervene on?
* Should we characterize the supervenience of the ethical in terms
of facts about individuals, or about whole possible worlds?
* What is the modal strength of the supervenience relation? Does it
hold only across worlds with the same laws of nature as ours, or
across all metaphysically, conceptually, or "normatively"
possible worlds?
* Thus far I have introduced ethical supervenience as a thesis about
what there is; is it better stated as a commitment concerning
combinations of our ethical attitudes?



The next four subsections consider these questions in turn. Before
turning to these questions, it is worth briefly highlighting a
different issue: which class of supervening properties to focus on? A
survey of the literature provides a variety of suggestions: relevant
supervening properties are characterized as *ethical*,
*moral*, *evaluative*, or *normative.* The nature
of each of these categories, and the relationship between them, are
both controversial. For example, some philosophers will question the
normative authority of morality, while others will think of
normativity as a very broad tent, including any rule- or
convention-governed activity, such as chess or etiquette. This entry
will not explore these interesting issues (see Baker 2017 for
discussion). Instead, it will provisionally assume that the
significance of supervenience is similar for each of these classes of
properties. For the sake of uniformity, the entry will focus on
ethical properties throughout.


### 1.1 What does the ethical supervene on?



Somewhat surprisingly, the idea of ethical supervenience can be made
to seem plausible despite the fact that it is difficult to provide a
characterization of *what* the ethical supervenes on that is at
once uncontroversial and theoretically interesting (see
 Section 5.4
 for further discussion of this point). This section briefly sketches
the options for characterizing what the ethical supervenes on, and
some difficulties that these options face.



The thesis used to introduce supervenience
above--Initial--suggested that the ethical supervenes on the
*natural* properties. This is the most common way of
characterizing ethical supervenience in the literature. However, there
are at least two difficulties with this idea. The first difficulty is
ambiguity: the term 'natural' has been characterized in
wildly varying terms in metaethics (see the introductory section of
the entry on
 moral non-naturalism
 for a brief survey of characterizations of the natural; see McPherson
2015, SS3-4 for one constructive proposal). The second
difficulty is that on many conceptions of the natural there will be
counterexamples to Initial. For example, many philosophers want to
contrast *natural* properties with *supernatural*
properties. Even if we assume that there are no actually instantiated
supernatural properties, we might allow that such entities are
*possible*. But this might in turn seem to suggest that two
possible states of affairs could be naturalistically identical, but
ethically different. For example, they might be different because of
ethically significant interactions between supernatural beings (Klagge
1984, 374-5; for some complications see McPherson 2015,
134-5).



This sort of worry might lead one to reject the common assumption that
the ethical supervenes on the *natural* as misguided; instead,
one might propose that the ethical supervenes on the
*non-ethical*. This might seem promising: the point of the
embezzling bank manager case might seem to be that there would need to
be some *non-ethical* difference between cases--natural or
not--in order for there to be an ethical difference in the bank
manager's actions. However, there is an important worry about
this way of characterizing the supervenience base (compare Sturgeon
2009, 70-72), which can be brought out briefly by example. Some
philosophers are sympathetic to ambitious reductive hypotheses about
ethics. On one such example, the ethical property of goodness is just
identical to the property of pleasantness. Because identicals have all
of the same properties, this would entail that pleasantness is an
ethical property. Some philosophers also think that certain
experiential or "phenomenal" properties, such as
pleasantness, are metaphysically fundamental, such that two possible
circumstances could differ only in how much pleasantness they
contained. Together, the points entail the conclusion that two worlds
could differ from each other solely in an ethical respect: how much
goodness/pleasantness they include. This is inconsistent with the
supervenience of the ethical on the non-ethical, but it is not clear
that we should be prepared to dismiss out of hand the assumptions that
generate this conclusion. This might in turn lead us to think that
there can at least be reasonable controversy concerning the
supervenience of the ethical on the non-ethical.



One can avoid this problem by proposing that the ethical supervenes on
the distribution of *all* of the properties. But this
formulation purchases plausibility at the price of triviality. Ethical
differences are differences, so there can obviously be no ethical
difference without *some* difference. In light of its
triviality, this sort of supervenience thesis fails to identify
anything in ethical supervenience that is of philosophical
interest.



An influential alternative way of characterizing what the ethical
supervenes on begins with a distinction in language. Some philosophers
think that we can intuitively distinguish between broadly
*evaluative* predicates (like 'is right', 'is
good', 'is virtuous', etc.) from
*descriptive* predicates (like 'is round',
'is accelerating', 'is a badger' etc.). We can
then ask about the relationship between the properties that are picked
out by these two sets of predicates. Frank Jackson has argued that
this allows us to state an ethical supervenience thesis: there is no
possible difference that can be stated using evaluative predicates
between states that are identical with respect to all properties
picked out by descriptive predicates (1998, 118-125).



Jackson's proposal seemingly avoids triviality, because
evaluative and descriptive predicates appear to be distinct. However,
the detour through language faces significant challenges. One
challenge concerns the expressive power of a language like ours: if it
is limited, then there seemingly might be ethical differences between
states of affairs that are not correlated with descriptive differences
expressible in a language like ours (for related worries, see Sturgeon
2009, 73-79). A second challenge questions whether the
distinction between description and evaluation is characteristically a
distinction in the semantic properties of predicates, as Jackson
assumes. On one contrasting view, evaluation might instead
characteristically be a pragmatic property of whole speech acts (see
Vayrynen 2013b for extended defense of this idea for the case of
"thick" evaluation.)



In the face of these difficulties, some philosophers have sought to
develop accounts of the class of properties which subvene the ethical
which are substantive enough for ethical supervenience to do
dialectical work, but avoid some of the difficulties just sketched.
For example, it has been proposed that the ethical supervenes on the
disjunctive class of *non-ethical or descriptive* properties
(Ridge 2007). In the context of discussing arguments concerning
supervenience and non-naturalism, it has been proposed that the
ethical supervenes on the set of properties that are not ethical
properties as those are understood by the non-naturalist (McPherson
2012).



There is a cross-cutting distinction that may be important for our
thinking about the supervenience of the ethical. Most properties are
*repeatable*, in the sense that they can be possessed by
distinct possible individuals. But some properties are not repeatable.
For example, the property of *being identical to Emad Atiq* is
not repeatable: it can only be borne by a single individual, across
modal space. It appears plausible that the ethical properties
supervene on a set of repeatable properties (Atiq forthcoming).



As this brief survey makes clear, it is not obvious how to
characterize what the ethical supervenes on, in a way that makes an
ethical supervenience thesis both plausible and theoretically
interesting. Now that the difficulties here have been made clear
(especially by Sturgeon 2009), this is an important potential locus
for future research. The following discussion largely sets aside these
debates, speaking of the supervenience of the ethical properties on
the *base* properties,where 'base' serves as a
placeholder for a more illuminating characterization of the class of
properties that subvene the ethical.


### 1.2 The structure of ethical supervenience



There are many possible structures of covariation that have been
called supervenience theses in the metaphysics literature. For our
purposes, it will be convenient to distinguish four of the most
influential formulations. (The literature on supervenience contains
several other variations; see the entry on
 supervenience
 for an excellent introduction, from which this entry adopts some of
the formulations below. That entry also has very helpful discussion of
the contrast between supervenience and certain other metaphysical
relations with which it is often associated. The contrast between
supervenience and the closely-related notion of entailment, discussed
in section 3.2 of the entry on
 supervenience,
 is especially germane to the topic of this subsection.)



One important structural distinction concerns whether a thesis makes
claims about the properties of individuals (*individual*
supervenience theses), or is cast in terms of the character of whole
possible worlds (*global* supervenience theses). The ethical
properties *globally supervene* on the base properties just in
case:



> 
> **Global**
>   
> 
> Every pair of possible worlds that has exactly the same world-wide
> pattern of distribution of base properties, also has exactly the same
> world-wide pattern of distribution of ethical properties (cf. the
> entry on
>  supervenience).
>  



Individual supervenience theses are so-called because they explicitly
state patterns of instantiation of properties by *individuals*
(rather than across whole possible worlds). There are two prominent
sorts of individual supervenience theses in the literature. The
ethical properties *weakly* supervene on the base properties
just in case:



> 
> **Weak**
>   
> 
> Necessarily, if anything *x* has some ethical property
> *F*, then there is at least one base property *G* such
> that *x* has *G*, and everything that has *G* has
> *F* (cf. the entry on
>  supervenience).
>  



The ethical properties *strongly* supervene on the base
properties just in case:



> 
> **Strong**
>   
> 
> Necessarily, if anything *x* has some ethical property
> *F*, then there is at least one base property *G* such
> *x* has *G*, and **necessarily** everything
> that has *G* has *F* (cf. the entry on
>  supervenience).
>  



The crucial difference between Strong and Weak supervenience is the
second necessity operator in Strong. An example will make the
difference here vivid: weak ethical supervenience is compatible with
it being a brute fact that there are both "utilitarian"
possible worlds where rightness covaries uniformly with happiness
maximization, and "Kantian" possible worlds, where
rightness covaries uniformly with satisfying the categorical
imperative. By contrast, strong supervenience denies this
possibility.



It is generally agreed that strong supervenience entails global
supervenience and weak supervenience; there is considerable
controversy about whether global supervenience entails strong
supervenience (see SS4.3 of the entry on
 supervenience).



Consider another important individual ethical supervenience relation,
inspired by Brian McLaughlin (1995, 24) but stated less
technically:



> 
> **Strong Intuitive**
>   
> 
> If two possible entities are alike in all base respects, they are
> alike in all ethical respects.
> 



If we interpret 'possible' here as representing
metaphysical modality, both McLaughlin and Jaegwon Kim (1993, 81) note
that the Strong and Strong Intuitive supervenience relations are
equivalent. However,
 Section 2
 below will show that if we reinterpret the modalities involved, these
theses will no longer be equivalent.


### 1.3 The modal strength of ethical supervenience



So far this entry has talked freely of necessity, possibility, and
possible worlds. However, one can use such talk to discuss importantly
different modal standards: for example, philosophers talk of
*logical necessity*, *conceptual necessity*,
*metaphysical necessity*, *nomic necessity*, and
*normative necessity.* The aim of this section is to briefly
orient readers to each of these notions. To begin, consider some
examples:


1. All bachelors are bachelors
2. All bachelors are unmarried
3. Nothing can travel faster than light
4. Atoms of gold contain 79 protons
5. Pain is bad



On one traditional gloss, a sentence is *logically necessary*
if it would remain true given any uniform and grammatically legitimate
reinterpretation of the non-logical expressions of that sentence.
Sentence (1) is a promising example: the only non-logical word in (1)
is 'bachelor', and any uniform and grammatically
appropriate interpretation of 'bachelor' in (1) will
result in a true sentence. (For more on logical truths, see the entry
on
 logical truth.
 Section 1.1 of that entry discusses the alleged modal force of
logical truths.)



By contrast, (2) is not a logical truth: one could easily hold fixed
its logical structure, but vary the meaning of 'bachelor'
or 'unmarried' and thereby produce a false sentence.
However, (2) is a promising candidate to be conceptually necessary. On
one gloss, a sentence is conceptually necessary (or
"analytically true") if it is true solely in virtue of the
meanings or concepts involved in the sentence. Sentence (2) is a
traditional example. If 'bachelor' means *unmarried
male*, then the meaning of the sentence suffices to explain why it
is true. (The notion of analyticity is famously controversial; for
discussion, see the entry on the
 analytic-synthetic distinction.)



Two notes are relevant here. First, some philosophers will talk of
'logical' necessity or supervenience as a way of
discussing what this entry is calling conceptual necessity or
supervenience. Here, as elsewhere, it is important to keep track of
what exactly an author intends to express by their terms. Second, some
proponents of analytic truth will nonetheless reject the idea of a
distinct conceptual *modality* (e.g. Jackson 1998, Ch. 3). Such
philosophers can, however, capture importantly related phenomena by
discussing modal claims formulated in terms of sentences and their
intensions.



Next consider (3): this does not seem to be true simply because of the
concepts it expresses. Rather, if it is true, it seems to reflect an
important law of nature: a deep and non-accidental pattern in our
universe. Some philosophers think that such laws underwrite a
distinctive sort of modality: a proposition is *nomically
necessary* just in case its falsity is incompatible with the laws
of nature. On this view, (3) is nomically necessarily true, because it
follows from the laws governing the speed of light.



Now consider (4). It is commonly thought that (4) is necessarily true.
For example: a substance composed overwhelmingly of atoms that do not
contain 79 protons in their nuclei could not be gold. But (4) does not
on its face look like a conceptual truth: it was a substantive
discovery that there were protons at all, let alone how many protons
an atom of gold characteristically possesses. Further (4) does not
seem like it reflects a law of nature in the way that (3) does:
rather, (4) seems to follow immediately from facts about what it is to
be gold. Examples like (4) thus purport to give us an initial grasp on
metaphysical modality as distinct from the other modalities considered
thus far.



Still more controversial is the notion of *normative necessity*
(Fine2002, Rosen 2020). One way of understanding this idea appeals to
an analogy with nomic modality. We can think of nomically necessary
facts as those which follow from facts about the laws of nature. For
example, the nomic impossibility of something traveling faster than
light is a direct consequence of it being a law of nature that that
nothing can travel faster than light. Someone might similarly claim
that there are fundamental *normative laws* or principles.
Suppose that (5) stated one of those laws. Then the normative
impossibility of a state's being good just because it is painful
could be understood as expressing a consequence of that underlying
normative law.



There is enormous controversy about each of these alleged varieties of
modality. For each of logical, conceptual, nomic, metaphysical and
normative flavors of modality, some philosophers have raised important
challenges to whether that flavor of modality is well-regimented,
theoretically useful, or genuinely distinct from others on the list.
This entry will not enter seriously into those debates. (For
discussion of some of the issues, see the entry on
 varieties of modality.)
 If we instead provisionally assume that each of these notions is
legitimate, this will put us in a position to ask (in
 Section 2,
 below): what is the modal strength of the supervenience thesis that
we should accept?


### 1.4 Ontological and ascriptive supervenience



The ethical supervenience theses discussed thus far are
*ontological*: they propose various covariance relationships
between ethical properties and certain other properties. However,
James Klagge (1988) has helpfully regimented an important alternative
way of understanding ethical supervenience. Call two circumstances
that a thinker believes to be identical in all base respects
*apparently base-identical*. Now consider the following
claim:



> 
> **Ascriptive**
>   
> 
> Anyone who treats apparently base-identical circumstances as ethically
> different from each other thereby makes a *mistake*.
> 



Unlike the supervenience theses encountered so far, Ascriptive is
fundamentally a claim about ethical *judgments*: it is a claim
that someone who makes a certain pair of such judgments thereby makes
a mistake. Klagge usefully dubs claims like this *ascriptive
supervenience theses*.



A fully informative ascriptive supervenience thesis would explain how
we should understand the *mistake* claimed by Ascriptive. There
are several possibilities, of which four are worth emphasizing. The
claimed mistake could be *alethic*, consisting in having made
at least one judgment with a false content. Or it might be
*epistemic*: consisting in making at least one epistemically
unjustified judgment. It could be *conceptual*, consisting in
judging in a way that is inconsistent with the meanings of ethical
words. Finally, it might be characterized as *ethical*,
consisting in making a judgment in a way that is vicious or ethically
objectionable. (Note that the relevant judgment might be mistaken in
more than one of these ways.)



Because ascriptive supervenience theses are about judgments rather
than relations between classes of properties, they are quite different
from the ontological supervenience theses we have considered thus far.
One way to bring this out is to notice that one could potentially
accept Ascriptive without thereby having any views about whether there
are ethical properties. On the other hand, there are interesting
connections between certain ascriptive and ontological supervenience
theses. For example, anyone who accepts Strong Intuitive seems to be
committed to a version of Ascriptive, with an alethic gloss on
'mistake'.



This entry began with the suggestion that it is plausible that the
ethical supervenes. This section has aimed to clarify some of our
options for understanding that idea. The various interpretive options
we have explored together suggest a dizzying space of possible ethical
supervenience theses. This in turn raises a pressing question: which
of these theses (if any) best articulate the plausibility and
significance that philosophers have often taken ethical supervenience
to have? One thing that might help to answer this question is to
consider the arguments that we can give for supervenience: these
arguments might favor some of these theses over others.


## 2. Arguments for Ethical Supervenience



It is common for philosophers to endorse ethical supervenience without
much argument (an important exception is Smith 2004; for critical
discussion of a variety of the arguments that have been offered, see
Roberts 2018, 10-18). Part of the reason for this is that
ethical supervenience is taken to be both obvious and uncontroversial.
(Rosen 2020 calls it "The least controversial thesis in
metaethics".) Further, ethical supervenience is often claimed or
assumed to be an obvious conceptual truth, doubts about which are
supposed to reveal conceptual incompetence. The discussion just
completed, however, suggests reason to worry about this assumption:
there is not one ethical supervenience thesis but instead a complex
variety of such theses. It is far from clear that we should accept all
of these theses, and a substantive question how to assess each of
them. Given that supervenience claims are modal claims, those seeking
to evaluate supervenience claims might begin by considering the
general question of how we can know modal facts (see the entry
 modality-epistemology/).



This section sets aside this broad question. Instead, it begins by
setting out a general strategy for arguing for ethical supervenience.
It then explores the implications of that strategy for the
controversies introduced in the previous section.



The general argumentative strategy has two elements. The first element
defends ethical supervenience as a plausible generalization from
cases. Thus, consider our orienting case of the embezzling bank
manager. This case provides us with a *specific ethical
supervenience thesis*: it suggests that the ethical quality of the
manager's action cannot vary without something else varying as
well (compare Horgan and Timmons 1992, 226 on *specific
supervenience facts*). Next, notice that there is nothing special
in this respect about the bank manager case: we can identify specific
supervenience facts about anything from genocide to insulting your
neighbor's hat. Each such fact is constituted by an interesting
necessary connection between ethical properties and some base
properties. It is theoretically unattractive to rest satisfied with a
long list of such necessary connections. Instead, we should look for a
single thesis that unifies all of these specific theses into a single
pattern. This pattern can be captured by a *general* ethical
supervenience thesis such as Initial (compare McPherson 2012,
211).



The second element of the general strategy for arguing for ethical
supervenience emphasizes the independent credibility of such a general
supervenience thesis. This element takes inspiration from a comment by
Henry Sidgwick:



> 
> In the variety of coexistent physical facts we find an accidental or
> arbitrary element in which we have to acquiesce.... But within
> the range of our cognitions of right and wrong, it will be generally
> agreed that we cannot admit a similar unexplained variation. (1907,
> 209)
> 



It is plausible to interpret Sidgwick as suggesting that although we
seek explanatory power when we develop our account of the physical
world, we need to be prepared to admit *brute contingency*: the
possibility that our best theories or explanations include claims like
"and these just happened to be the initial conditions", or
(to be anachronistic) "it is a brute fact that the quantum wave
function collapsed *this way*". By contrast, we cannot
admit the analogous idea that it is a brute contingent fact that a
certain ethical property just happens to covary with the base
properties that are instantiated around here. Because of their modal
scope, ethical supervenience theses reflect this ban on brute ethical
contingency (compare also Shafer-Landau 2003, 78; Smith 2004,
225).



The two parts of the strategy complement each other: The first part of
the strategy defends general ethical supervenience on the basis of
unification, which is a familiar and domain-general theoretical
virtue. The second part of the strategy suggests that we have further
reasons to accept such a general thesis that stem from a feature of
our understanding of the ethical domain specifically.



While Initial is a general supervenience thesis, it is silent on many
of the issues broached in
 Section 1.
 The next task is thus to extend the strategy just introduced to
discuss those issues. Before doing so, it is important to emphasize
that many of the options considered in that section are
*compatible*: for example, supervenience on the natural
properties entails supervenience on all of the properties. Because of
this, an argument for the former thesis is not an argument against the
latter thesis. Because stronger ethical supervenience theses are
potentially both more illuminating and more dialectically significant,
this section will focus on examining competing cases concerning what
the *strongest* well-supported ethical supervenience thesis
is.



The general strategy just canvassed has two stages: the first stage
carefully examines cases, and the second appeals to our more general
understanding of the ethical. Both parts of the strategy can be useful
in addressing the question of what the ethical supervenes on. For
example,
 Section 1.1
 appealed to possible cases involving supernatural beings as part of
an argument against the idea that the ethical supervenes on the
natural. In terms of the first part of the strategy, this suggests
that once we make salient the possibility of supernatural beings,
ethical supervenience theses that posit a naturalistic base become
more doubtful. In terms of the second part of the strategy, the same
cases fit nicely with the Sidgwickian thesis: if an ethical claim were
true in part because of some supernatural truth, it would thereby not
be brutely true. As noted in
 Section 1.1,
 characterizing what the ethical supervenes on is an open challenge.
This merely illustrates how the strategy can be applied to make
progress on that challenge.



The general strategy can also be applied to the structural question:
for example,
 Section 1.2
 noted that weak supervenience is compatible with the idea that a
utilitarian ethical principle is a fundamental truth in some possible
worlds, but is false in others. Strong ethical supervenience, by
contrast, is incompatible with this idea. Many philosophers believe
that the fundamental ethical principles could not vary contingently in
this way, because this would again threaten to entail that some
fundamental ethical truths are brute contingencies. If correct, this
supports the idea that ethical supervenience is a strong supervenience
thesis. On the other hand, assessing whether ethical supervenience is
strong or global (or both) might require adjudicating live
metaphysical controversies concerning the relationship between strong
and global supervenience (for discussion of these controversies, see
section 4.3.1 of the entry on
 supervenience).



What about the *modality* of ethical supervenience? One might
think of this question as seeking to clarify what sort of
non-contingency the Sidgwickian commitment requires. If we distinguish
logical from conceptual necessity, it is easy to see that the
*logical* supervenience of the ethical is a non-starter. The
truth of 'pain is bad', e.g., is not secured simply by the
logical vocabulary and the syntax of the sentence, in the way that the
truth of 'all bachelors are bachelors' seemingly is.



The most common view in the literature is that the supervenience of
the ethical is a conceptual truth. Here we cannot simply adapt the
general strategy used so far, since neither the cases nor the
inference to the best explanation from those cases seems to settle the
matter. Consider three reasons to think that ethical supervenience is
a conceptual truth.



First, to adapt R. M. Hare's canonical example (1952,
SS5.2), if I mentioned to you that one possible act was right, and
another wrong, despite these acts being exactly alike in all other
respects, your initial reaction would be puzzlement, and if I
persisted in my view upon interrogation, you might start to worry that
I was simply confused or misusing words. Second, the crucial cases
used to support supervenience--like the embezzling banker
case--seem to involve *conceivability reasoning*: we are
asked to consider two circumstances that are identical in all base
respects, and notice that we cannot make sense of the idea that they
differ in ethical respects. Some philosophers find it natural to think
that conceivability reasoning first and foremost reveals facts about
conceptual possibility and necessity. This can be bolstered by a third
(much more controversial) thought. Conceivability reasoning appears to
be a priori. But if such reasoning fundamentally concerned the world
rather than our concepts, then we would seemingly have a priori access
to substantive facts about the world, which many philosophers have
found deeply mysterious.



Each of the sorts of reasons just offered is controversial. Consider
three examples of this controversy. First, it is controversial whether
the sorts of puzzlement reactions identified by Hare must signal
conceptual confusion or misuse (Kramer 2009, Harrison 2013). For
example, perhaps we take ethical supervenience claims to be so obvious
that when someone appears to deny them, we are inclined to treat
conceptual confusion or difference as a charitable hypothesis. One
potential piece of evidence for this is that when denial of ethical
supervenience is based upon reasoned arguments, such as those
mentioned in
 Section 5
 below, a diagnosis of conceptual confusion or difference arguably
become less plausible diagnosis.



Second, philosophers unafraid of the 'synthetic a priori'
can reject the inference from conceivability reasoning to conceptual
status. It is notable here that a great deal of work in contemporary
metaphysics appeals to something like conceivability reasoning to
argue directly for claims about the nature of reality. Third, the very
notion of conceptual truth is hotly contested: many philosophers have
become convinced that there is no notion of conceptual truth that is
both coherent and philosophically interesting (for discussion, see the
entry on the
 analytic-synthetic distinction).



Set aside these challenges for the moment, and consider how we should
interpret the idea that ethical supervenience is a conceptual truth.
We saw above that there is some support for thinking that ethical
supervenience is a strong supervenience thesis. But combining this
idea with the idea that the modality of supervenience is conceptual
leads to complications. To see the issue, recall the schema for Strong
Supervenience:



> 
> **Strong**
>   
> 
> *Necessarily*, if anything *x* has some ethical property
> *F*, then there is at least one base property *G* such
> that *x* has *G*, and *necessarily* everything
> that has *G* has *F*.
> 



If we interpret the claim that ethical supervenience is conceptual by
replacing 'Necessarily' in the schema with 'it is a
conceptual truth that'. The result is:



> 
> **Strong Conceptual**
>   
> 
> *It is a conceptual truth that* if anything *x* has some
> ethical property *F*, then there is some base property
> *G* such that *x* has *G*, and *it is a
> conceptual truth that* everything that has *G* also has
> *F*.
> 



One central problem with Strong Conceptual is that it claims that for
every instantiated ethical property, there is a base property such
that: it is a conceptual truth that anything that has this base
property also has the ethical property. And this consequence will seem
defensible only on certain very controversial views about ethics and
conceptual analysis.



The implausibility of Strong Conceptual may explain why two of the
most influential philosophers who discussed supervenience in ethics
--R. M. Hare (1984, 4) and Simon Blackburn (cf. 1985, 134, and
the contrast between 'supervenience' and
'necessity' in 1984, 183-4.)--seemed to accept
something like weak but not strong conceptual supervenience of the
ethical.



However, as noted above, it appears that we have reason to accept
something stronger than weak ethical supervenience (Shoemaker 1987,
440-1; for dissent see Miller 2017). It is thus worth
considering alternatives that capture that strength without succumbing
to the difficulties facing Strong Conceptual. One way to avoid the
problem is to interpret the first necessity operator in Strong as
conceptual, while leaving the second operator as metaphysical:



> 
> **Strong Mixed**
>   
> 
> It is a conceptual truth that if anything *x* has some ethical
> property F, then there is some base property *G* such that
> *x* has *G*, and *it is metaphysically necessary
> that* everything that has *G* also has *F* (compare
> Dreier 1992, 15).
> 



This avoids the implausible implications that Strong Conceptual has:
Strong Mixed says only that it is a conceptual truth that a certain
base property (we may not know which) covaries with each ethical
property.



Note that Strong Mixed is only one possible mixed-modality
supervenience thesis: one could reinterpret either necessity operator,
to produce one of a wide variety of possible mixed ethical
supervenience theses. For example, the second necessity operator could
be interpreted as normative (rather than metaphysical) necessity. Such
mixed modality theses have not yet been seriously explored.



Another option is to offer a conceptual version of the Strong
Intuitive supervenience thesis mentioned in
 Section 1.2:



> 
> **Intuitive Conceptual**
>   
> 
> If two conceptually possible entities are alike in all base respects,
> they are alike in all ethical respects.
> 



Because it does not posit known relations between specific ethical and
base properties, Intuitive Conceptual does not face the difficulties
of Strong Conceptual. Intuitive Conceptual also has an advantage over
Strong Mixed: the latter commits one to metaphysical as well as
conceptual modality. Intuitive Conceptual is a plausible option for
philosophers who take there to be a stronger alternative to weak
ethical supervenience, but who are suspicious of the notion of
metaphysical modality.



Among philosophers who reject the idea that ethical supervenience is a
conceptual truth, many will insist that the supervenience of the
ethical is at least metaphysically necessary. Most such philosophers
appear happy to accept the strong metaphysical supervenience of the
ethical. Such philosophers might defend the metaphysical supervenience
of the ethical by applying the general strategy suggested at the
beginning of this section, while rejecting the case for thinking this
strategy has specifically conceptual implications. Other philosophers
will reject the idea that we should begin with the sorts of judgments
about cases that drove the general strategy. They can instead argue
that the metaphysical supervenience of the ethical is supported as an
abstract consequence of the best overall empirical theory concerning
ethical facts (e.g. Sturgeon 2009, 61).



Other philosophers reject the conceptual and metaphysical
supervenience of the ethical, but claim that the ethical supervenes
nomically or normatively. In general, such supervenience theses are
too weak to support the sorts of arguments from ethical supervenience
that philosophers have made. Because of this, arguments for these
theses will be discussed in
 Section 5.4,
 which concerns doubts about ethical supervenience.



Finally, how should we decide between ontological and ascriptive
supervenience theses? Proponents of ascriptive supervenience take on
the obligation of making precise the sort of mistake that
'supervenience-violators' are allegedly making, and
defending the idea that this is a mistake. The most prominent approach
takes the mistake to be conceptual, which involves commitments similar
to those taken on by defenders of the conceptual supervenience theses
just discussed.



One reason to focus on ascriptive supervenience theses is that some
philosophers deny that our ethical thought and talk commits us to the
existence of ethical facts and properties. Such philosophers can still
grant that if we interpret supervenience in an ascriptive way, it
provides important insights into ethics. Further, philosophers who
accept that there are ethical facts and properties can also accept
ascriptive supervenience theses about ethical thought. Indeed, if we
understand Ascriptive as a conceptual claim, then together with
realism it could provide the basis for accepting a conceptual-strength
ethical supervenience thesis. This means that ascriptive ethical
supervenience theses have the potential to be a point of significant
common ground between philosophers with widely differing views about
the nature of ethical thought and talk. And this might make them
especially dialectically powerful in arguments that appeal to ethical
supervenience.


## 3. Arguments from Ethical Supervenience



This section examines arguments in and about ethics that philosophers
have made which appeal centrally to ethical supervenience as a
premise. The bulk of the section discusses the most influential
supervenience arguments in ethics, which have concerned realism and
reduction, before considering the significance of ethical
supervenience for the epistemology of ethics, and for debates about
the existence of ethical principles.


### 3.1 Arguments against realism



The earliest influential discussions of what we now call supervenience
in ethics focused on its significance for substantive ethical
investigation. Henry Sidgwick draws from it what he takes to be a
"practical rule of some value" for such investigation
(1907, 208-9). And G. E. Moore (1922) used the idea as part of
his attempt to explain the idea of intrinsic value. Given that Moore
and Sidgwick were both ethical realists, it is perhaps striking that
the most influential philosophical use of ethical supervenience has
been in arguments against ethical realism.



In his argument for error theory, J. L. Mackie briefly claims that
supervenience makes trouble for the realist. His quick argument can
usefully serve as a prelude to the more detailed discussion to come.
Mackie suggests that we think that actions have their ethical
properties *because* they have some natural features. For
example, we think a certain action wrong because it is cruel. He
denies that this 'because' references a conceptual
entailment, and thinks this raises two questions: (1) what sort of
relation *is* the connection being referred to? And (2) how do
we come to know that actions stand in this relation? (1977, 41). As it
stands, Mackie's questions serve more as a research agenda than
an argument (for important recent discussion, see Olson 2014,
SS5.1). It appears plausible that realists should aim to have
something illuminating to say both about the nature of the relation
between the ethical and base properties, and a credible epistemology
for how we come to know such relations. But Mackie's questions
do not yet constitute an argument that realists cannot achieve these
aims.



Simon Blackburn developed a more substantial supervenience argument
against realism. The details of Blackburn's various
presentations of his argument (1971, 1984, and 1985) are complex and
raise difficult interpretive questions; the reconstruction that
follows is a rather free interpretation of Blackburn's (1984,
183-4; for sympathetic discussion, see Mabrito 2005 and Mitchell
2017). The argument starts with two claims:


1. It is conceptually necessary that if any two things are
naturalistically identical, then they are ethically identical
2. No specific naturalistic description (of an agent, action, state
of affairs, etc.) conceptually entails an ethical description. (For
example, act-utilitarianism is not a conceptual truth, neither is
Kantianism, etc. Indeed, both act-utilitarianism and Kantianism are
conceptually possible.)



Now consider an act of happiness-maximizing promise-breaking. It
follows from (2) that is conceptually possible that the world is
base-identical to the actual world, and this act is wrong, but it is
also conceptually possible that the world is base-identical to the
actual world, and this act is not wrong. But from (1), we can notice
that it is *not* conceptually possible that there are two
base-identical acts, one of which is wrong and one of which is
not.



This combination is supposed to be difficult for the realist to
explain. For (2) seems to show that there is no conceptual link
between ethical concepts like 'wrong' and any one of our
naturalistic concepts. And if ethical concepts function to pick out
properties (as the realist claims), then given this conceptual
separation, it seems that we should be able to identify conceptual
possibilities by arbitrarily "mixing and matching"
distributions of naturalistic and ethical properties. Ethical
supervenience precisely functions to limit such mixing and
matching.



Consider four possible ways that the realist might reply. First, the
realist could seek to debunk the challenge. For example, she might do
this by denying that the ethical supervenes with conceptual necessity
(see
 the previous section
 for discussion). Or she might reject the supervenience of the ethical
on the *natural* (see
 Section 1.1),
 and challenge Blackburn to identify a supervenience base for which
the argument remains potent.



Second, the realist might seek to explain the pattern of individual
conceptual possibility without conceptual co-possibility. For example,
if it were a conceptual truth that ethical properties were natural
properties, then this would explain the pattern of knowledge suggested
here (Dreier 1992, 20). An analogy may help to make this vivid: it
might be a conceptual truth that physical properties are natural
properties (compare Kim 2011). But which total naturalistic patterns
in the world the physical properties covary with is arguably an
empirical question. One might take these examples to illustrate a
general reply: the pattern is not puzzling, because it simply reflects
the limitation of our conceptually-based insight into reality
(Shafer-Landau 2003, 86).



Third, some realists are prepared to claim more ambitiously that we
can give a *conceptual analysis* of rightness in base terms
(e.g. Jackson 1998, Ch. 5). Such philosophers can thereby deny (2),
cutting the argument off at the knees. (Dreier 1992, 17-18
suggests that Blackburn's argument simply begs the question
against this sort of reductive realist.) Such realists take on the
burden of rejecting the most famous argument in metaethics: G. E.
Moore's "open question argument" (1903, Ch. 1).
However, it is a hotly contested question what--if
any--probative value this argument has (for discussion, see
section 2 of the entry on
 moral non-naturalism).



A fourth reply would be to shrug off the alleged explanatory
challenge. However allegedly puzzling the combination of the features
described by (1) and (2) are, they are consistent features of a
concept. This means that we could choose to introduce a concept that
exemplified those features. It might thus be suggested that
Blackburn's argument shows only that we have chosen to do so
with our ethical concepts (compare Olson 2014, 89-90). One might
reply to this last point that it is precisely this choice that needs
to be explained. Blackburn argues that the non-cognitivist has a
smooth functionalist explanation for why our ethical thought and talk
includes the ban on mixed worlds (see
 Section 3.3
 below for discussion), while for the realist, this might just be an
unexplained peculiarity of our choice of concepts.


### 3.2 Arguments against non-reductive realism



As was just noted, a certain kind of reductive naturalist seems to
have an easy reply to Blackburn's argument. In light of this, it
is perhaps unsurprising that several philosophers have argued that
ethical supervenience theses support reductionist forms of ethical
realism against non-reductive forms. Consider a few important variants
of such arguments.



The first is a simplified version of arguments due to Frank Jackson
(1998, Ch. 5; see also related arguments by Brown 2011 and Streumer
2017, Ch.s 2-3). The argument has two steps. The first step is an
argument that if the ethical properties strongly (or globally)
metaphysically supervene on the base properties, then there is no
metaphysically possible ethical difference between states that does
not have a correlated base difference between the same states. If we
make some liberal assumptions about property types, this entails in
turn that there is a base property that is necessarily coextensive
with every ethical property.



The second step of the argument is the claim that necessarily
coextensive properties are identical. Brown offers a nice motivation
for this thesis: we should commit ourselves to the existence of a
property only insofar as it can do explanatory work, and the only way
for a property to do explanatory work is for it to distinguish
metaphysical possibilities (2011, 213). If we assume that identity is
sufficient for reduction, these two steps together entail the
reduction of the ethical.



While both steps of the argument are controversial, the second stage
has come in for especially heavy fire. (For a careful discussion of
the dialectic, see Suikkanen 2010; for an ingenious argument against
Jackson that identity with *descriptive* properties is
compatible with ethical non-naturalism, see Dunaway 2017). One
important general basis for doubt is that many contemporary
philosophers question whether modality constitutes the fundamental
explanatory currency of metaphysics, as Jackson and Brown seem to
presuppose (for an especially influential challenge see Fine 1994, for
an especially radical challenge, see Sider 2011, Ch. 12).



The argument for reduction from metaphysical supervenience can,
however, be prosecuted within frameworks that reject Jackson's
and Brown's core assumptions. Consider two examples. First, one
might deny that necessary coextension entails identity, but
nonetheless argue that the best explanation of ethical supervenience
is a grounding relation that suffices to ensure that ethical
properties are identical to some of the base properties (Bader 2017).
Second, you might deny that reduction requires identity. Of course,
identifying non-obvious identities is a powerful model of reduction.
For example, a standard way of characterizing the physicalistic
reduction of heat is that the heat in a volume of gas is
*identical* to the mean molecular kinetic energy of that volume
of gas, which is a physical property. However, there is no consensus
concerning how to understand reduction as a metaphysical relation (for
a taste of the controversy, see McPherson 2015, SS3, and the entry
on
 scientific reduction
 and the discussion of reduction in the entry on
 David Lewis).



The core idea at stake in debates over reduction is that commitment to
the existence of the reduced properties should constitute no
ontological commitment "over and above" commitment to the
reducing properties. Some philosophers have sought to spell out this
idea by appealing to *essence* rather than to identity.
Consider an essentialist account of reduction (cf. Rosen 2017b, 163),
on which the *A* properties reduce to the *B*-properties
just in case:



> 
> 
> (i) it is necessary and sufficient for each *A* property to be
> instantiated that some *B* property is instantiated; and
> 
> 
> 
> (ii) these modal facts follow from the essences of the
> *A*-properties.
> 
> 
> 



The idea is that if *what it is to be* each A property entails
that the A-properties are uniquely realized by the B-properties, this
amounts to a kind of reducibility of the A-properties. Consider an
example: one might take oneself to have offered a reduction of the
number one, in claiming that: *what it is to be the number one*
is just to be the successor of zero. One important contrast with the
identity conception is that on the essentialist conception, successful
reductions reveal metaphysical structure. Thus, one might say in our
example that the number one is 'built out of' the number
zero and the successor function.



On an influential essentialist account of *metaphysical
modality*, all necessities are to be explained by facts about the
essences of things. Ralph Wedgwood (2007) and Gideon Rosen (2020)
argue that on this sort of view, the strong metaphysical supervenience
of the ethical would entail that the ethical possibilities are fully
explained by the essences of the base entities.



Interestingly, both Rosen and Wedgwood reject this reductive
conclusion. Wedgwood argues that some necessary truths (including
ethical supervenience theses) can be explained by certain contingent
truths, together with facts about essences, and that this sort of
explanation does not have reductive implications (2007, SS9.3; for
critical discussion of this response, see McPherson 2009, Sec 3, and
especially Schmitt and Schroeder 2011). Rosen responds by rejecting
the strong metaphysical supervenience of the ethical (see
 Section 5.3
 below).


### 3.3 Supervenience and anti-realism



As
 Section 3.1
 explained, supervenience arguments were initially used by Mackie and
Blackburn to raise doubts about ethical realism. Indeed, it has been
widely assumed that the realist faces a challenge here that the
anti-realist does not. The issues here are complicated, and it will be
helpful to consider common varieties of ethical anti-realism
separately.



First, consider *ethical nihilism*, the thesis that there are
no ethical properties. The ethical nihilist might seem to have an easy
time explaining the metaphysical supervenience of the ethical: if
there are no ethical properties, there are, trivially, no ethical
differences. And if there are no ethical differences, there are no
ethical differences without base differences.



This line of reasoning is too quick as it stands. Supervenience is a
modal claim, so *contingent ethical nihilism*--the thesis
that there are no *actually instantiated* ethical
properties--cannot explain ethical supervenience. Indeed, as
Christian Coons (2011) has shown, it is possible to use supervenience
to construct an interesting argument *against* contingent
nihilism. A crucial question here is: what is the modality of the
supervenience thesis to be accounted for? If the supervenience thesis
we need to explain is conceptual, then even the truth of
*non-contingent nihilism*--the thesis that it is
metaphysically impossible for ethical properties to be
instantiated--would not do the relevant explanatory work. Only
the thesis that the instantiation of ethical properties is
*conceptually impossible* would suffice. (Note that the
nihilist might be able to adapt one of the realist replies to
Blackburn discussed in
 Section 3.1,
 but in this case it would not be *easier* for the nihilist to
explain supervenience, than it is for the realist who adopts the same
reply.)



The nihilist imagined above does not question the assumption that
ordinary ethical thought and talk commits us to ontological claims.
Other ethical anti-realists, however, will deny this assumption (for
discussion, see the entries on
 moral anti-realism
 and
 moral cognitivism vs. non-cognitivism).
 Consider two examples of such views.



First, *hermeneutic fictionalists* about ethical thought and
talk argue that such thought and talk is to be understood as a form of
pretense or fictional discourse (see Kalderon 2005 for discussion and
defense). It will be natural for the hermeneutic fictionalist to
reject ordinary ethical supervenience claims as misleading. However,
they will presumably still need to account for the considerations that
lead other philosophers to accept ethical supervenience claims. The
issues concerning ethical fictionalism and supervenience are
comparatively unexplored; see (Nolan, Restall, and West 2005,
325-327) for important preliminary discussion.



Second (and much more influentially) some *non-cognitivists*
about ethical thought and talk deny that our ethical claims express
beliefs about the ethical nature of the world, suggesting instead that
they express desire-like mental states. Such a view may make
ontological supervenience claims about ethics appear misleading at
best. More interesting is the question of what non-cognitivists can
say about the sort of ascriptive supervenience thesis discussed in
  Section 1.4:



> 
> **Ascriptive**
>   
> 
> Anyone who treats apparently base-identical circumstances as ethically
> different from each other thereby makes a mistake.
> 



This thesis is an alleged correctness constraint on ethical thought
and talk. Prominent philosophers in the non-cognitivist tradition
(broadly understood) have characteristically claimed that their views
enabled them to explain theses like Ascriptive.



Consider a representative sample of these explanations. R. M. Hare
claims that ascriptive supervenience holds because a significant part
of the function of moralizing is to teach others our ethical
standards, and the only way to do that is to get our audience to see
the recognizable pattern that we are prescribing that they follow
(1952, 134). According to Simon Blackburn, the presumption of
ascriptive supervenience is required by the idea that our ethical
attitudes are supposed to be practical guides to decision-making
(1984, 186). According to Allan Gibbard (2003, Ch. 5), ascriptive
supervenience for ethical thought is explained by a consistency norm
on planning states.



Critics of non-cognitivism (e.g. Zangwill 1997, 110-11; Sturgeon
2009) have challenged the rationales offered by Hare and Blackburn.
Suppose that we grant that consistency is useful, given the various
functions of ethical discourse. It is unclear why this usefulness
should force on us a *conceptual truth* about moral discourse.
Further, it is arguable that all that is required for these practical
purposes is consistency within worlds that are very similar to the
actual world. So the idea that such consistency is required over every
possible world (as seems to be the case for ethical supervenience)
seems like considerably more than the practical considerations
require. Gibbard's rationale has faced related criticism: why
must planners be committed to consistency in the sweeping way that
Gibbard envisions (Chrisman 2005, 411-12; Sturgeon 2009,
84-87)? If these critics are right, it is not clear that the
non-cognitivist has an especially compelling explanation of ethical
supervenience. And if they do not, this will complicate their efforts
to claim that explaining ethical supervenience is a dialectical
advantage against cognitivism. It is also worth bearing in mind that
the details of which ethical supervenience thesis we need to explain
can affect how promising the non-cognitivist explanations will be. For
an important illustration of this point, see (Atiq 2019).



A further complication arises from the fact that leading contemporary
heirs of non-cognitivism (such as Blackburn and Gibbard) have
abandoned anti-realism. Instead, they have adopted what Simon
Blackburn (e.g. 1993) has dubbed the 'quasi-realist'
program. This involves the claim that one can, while beginning with
the non-cognitivist's framework, "earn the right" to
realist-sounding claims about ethical truth and objectivity (for
further discussion see the section on noncognitivism in the entry on
 moral anti-realism).



Now consider an ontological supervenience claim: that there can be no
difference in ethical properties without a difference in base
properties. The quasi-realist program can seem to commit the
quasi-realist to accepting this claim. Dreier (2015) argues that this
leads to a further challenge to the non-cognitivist: *even if*
she can explain ascriptive supervenience, it is not clear that she can
explain ontological supervenience. If this is the case, the most
influential contemporary non-cognitivists may find that supervenience
is a dialectical burden rather than benefit.


### 3.4 Supervenience and moral epistemology



So far, this entry has focused on the significance of supervenience
for claims about the nature of ethical thought, talk, and metaphysics.
However, influential early discussions of this sort of thesis seemed
to have something else in mind. For example,
 Section 2
 above quoted an evocative passage from Henry Sidgwick. But
Sidgwick's point was not to argue about the metaphysics of
ethics. Rather, he was proposing a supervenience-like idea as an
epistemological corrective to ad hoc special pleading in one's
ethical reasoning (1907, 209).



The mere fact of supervenience could not play this sort of role: after
all, the supervenience of the ethical is compatible with the idea that
everyone ought always to do what I want them to do. However, Sidgwick
points to an important idea: that we expect there to be a rational
explanation for any ethical fact. One ambitious way of developing this
idea has been suggested by Nick Zangwill (2006). According to
Zangwill, a central conceptual constraint on ethical reasoning is the
"because constraint": when we judge something to be wrong
(or to have another ethical property), we are committed to its having
this property *because* it has some other property. Zangwill
claims that this principle "either is, or explains"
ethical supervenience (2006, 273). And Zangwill goes on to argue that
this constraint has striking epistemological implications: he claims
that it entails that our *only* epistemic access to facts about
the distribution of ethical properties is by knowing about the
distribution of base properties, and knowing ethical principles that
link the presence of base properties to ethical properties. He then
argues that our knowledge of these ethical principles could itself
only be a priori (2006, 276). If Zangwill is right about this, then
the a priori character of moral epistemology can be derived from
claims about the supervenience of the ethical.



One worry about this argument is that it might overgeneralize. The
"because" structure seems to be shared by other normative
domains: it would be very odd to claim that a particular chess move
was winning, or that a particular action was illegal, without being
committed to their being some general explanation in terms of the
rules of chess, or the relevant laws, that explains this particular
fact. But our knowledge of the law and the rules of chess is
empirical. So one might wonder what precisely prevents our knowledge
of ethical principles being empirical as well.


### 3.5 Supervenience and the existence of ethical principles



One traditional assumption about ethics is that our ethical
obligations can be expressed by general ethical principles. This
assumption has recently been challenged by ethical
*particularists*, who claim that our ethical reasons and
obligations cannot be codified into principles. Supervenience might
seem to be relevant to this debate. For as
 Section 3.2
 above showed, some philosophers argue that the strong metaphysical
supervenience of the ethical entails that for every ethical property,
there will be a base property that is necessarily coextensive with it.
Focusing on wrongness, this in turn has the apparent consequence that
there is a base property *B* such that:



> 
> **Entailment**
>   
> 
> It is metaphysically necessary that an action is wrong just in case
> that action is *B*.
> 



One might think that Entailment just is the schema for an ethical
principle concerning wrongness: for example, if we substitute
'fails to maximize happiness' for 'is
*B*' we seem to get a clear statement of a utilitarian
ethical principle. And this in turn might seem to cast doubt on the
coherence of particularism.



This reasoning, however, is too quick. To see this, note that
supervenience itself in no way guarantees that *B* will be some
elegant base property like failing to maximize happiness. *B*
might instead be enormously complicated: at the limit, supervenience
is compatible with *B* simply being a disjunction of an
infinitely long list of complete base specifications of various
possible worlds. Call an instance of Entailment with such a base a
*gruesome entailment*. It is not clear that such entailments
constitute principles that are incompatible with particularism. One
reason to think that they do not is that genuine ethical principles
arguably have *explanatory power*. Margaret Little argues that
the "radical over-specificity" of gruesome entailments
renders them non-explanatory, and hence inapt to be principles (2000,
286). Another reason to doubt that gruesome entailments are principles
is that we ordinarily assume that ethical principles would be usable
by agents (Dancy 2004, 87-8), but a gruesome
"principle" is clearly not. (For a relevant argument that
the true instance of Entailment *could not* be gruesome,
because it would need to be learnable by ordinary speakers, see
Jackson, Pettit, and Smith 2000).


## 4. Metaphysical Supervenience and Ethical Realism



The Blackburn-inspired argument against ethical realism relies
crucially on the assumption that ethical supervenience is a conceptual
truth. For thesis (2) was crucial to that argument:



> 
> **2**. No specific naturalistic description of an action
> conceptually entails an ethical description....
> 



While many find (2) plausible, fewer would be prepared to accept a
purely metaphysical version of this thesis, such as:



> 
> **2\***. No base way a world could be metaphysically
> necessitates that world being a certain ethical way.
> 



This is precisely because thesis (2\*) is inconsistent with the strong
metaphysical supervenience of the ethical, which very many
philosophers accept. This means that a purely metaphysical variant of
Blackburn's argument will not be plausible.



This does not mean, however, that treating ethical supervenience as a
non-conceptual truth renders it dialectically inert. This section
considers the significance of metaphysical supervenience for ethical
realism: does it pose a challenge to ethical realism? If so, how can
we best understand this challenge? And what resources do different
sorts of ethical realist have to meet the challenge?



To focus our discussion, assume this metaphysical variant of Strong
Intuitive (cf. Rosen 2020):



> 
> **Intuitive Metaphysical**
>   
> 
> If two metaphysically possible entities are alike in all base
> respects, they are alike in all ethical respects.
> 



Intuitive Metaphysical might pose a challenge to the ethical realist
in light of one of at least two background ideas. First, some
philosophers have argued that there are no necessary connections
between "distinct existences," a claim that is sometimes
called Hume's dictum. If Hume's dictum is correct, then
the ethical realist will be committed to the ethical not being
distinct in the relevant sense from what it supervenes on. The
metaphysical use of Hume's dictum faces at least two formidable
challenges. The first is to clarify the dictum in such a way that it
is both interesting and a plausible candidate for truth. To see this,
note that many non-identical properties are necessarily connected: for
example, a surface's being scarlet entails that it is red, but
being scarlet is not identical to being red. Red and scarlet, then,
must not count as distinct in the sense relevant to a plausible form
of the dictum. This raises the question: what does distinctness amount
to? If we use necessary connection as a criterion, then Hume's
dictum turns out to be a trivial way of tracking this way of using the
word 'distinct'. Second, Hume's dictum is usually
defended on directly intuitive grounds. This raises a deep
methodological question: if we notice a conflict between Hume's
dictum and another intuitively plausible claim, why should we retain
Hume's dictum and jettison the other claim? (For helpful
discussion of Hume's Dictum, see Wilson 2010).



Consider a second way of developing a challenge to the ethical
realist, inspired by the Sidgwickian motivation for accepting ethical
supervenience, introduced in
 Section 2.
 According to this motivation, we should accept an ethical
supervenience thesis because doing so rules out the implausible
hypothesis of brute ethical contingency. Intuitive Metaphysical
clearly satisfies this motivation: it permits no brutely contingent
ethical variation. However, suppose that it was not possible to
explain why the ethical properties supervene on the base properties.
Then the very thesis that we used to explain why there was no brute
ethical contingency would turn out to be something arguably even more
peculiar. It would be a metaphysically necessary connection that
nonetheless has what Sidgwick might call an "arbitrary element
in which we have to acquiesce;" in a slogan: a *brute
necessity*.



A natural way of thinking about the significance of brute necessity
begins with the assumption that we are entitled to a default
*combinatorial* assumption about modality: that for any pair of
properties *F* and *G*, it is possible that there is an
*x* that is both *F* and *G*, that *x* is
only one and not the other, and that there is an *x* that is
neither *F* nor *G*. The next step is to suggest that
this default assumption can be defeated. Consider red and scarlet: on
one view, to be red just is to be *scarlet or crimson or cherry red
or...* The thesis that this is what it is to be red, if true,
would provide a straightforward explanation of why the combinatorial
assumption is defeated here: it is not possible for something to be
scarlet but not red precisely because of what it is to be red. Where
we take there to be no such explanation however, we should be loathe
to accept an alleged necessary connection (cf. McPherson (2012); for a
similar idea in a different context, compare Levine and Trogdon 2009).
Call this constraint on our metaphysical theorizing
*anti-brutalism.*



Both Hume's dictum and anti-brutalism put us in a position to
pose a conditional challenge to the ethical realist. If the realist
thinks that the ethical properties are distinct from the base
properties, they must reject either metaphysical supervenience or
Hume's dictum. And if they think the supervenience of the
ethical is a brute necessity, they need to explain why such brutalism
is not objectionable. Different variants of ethical realism have
different resources available to address this challenge. The remainder
of this section examines some of these resources.


### 4.1 Reductive explanations of ethical supervenience



As
 Section 3.2
 explained, some philosophers have argued that the supervenience of
the ethical entails that the ethical can be reduced. These arguments
are quite controversial, but it is perhaps less controversial that a
successful reduction of the ethical properties would suffice to
explain the metaphysical supervenience of the ethical.



Consider first a reductive account that identifies the ethical
properties with some natural or supernatural property. Assuming that
natural and supernatural properties are among the base properties, the
supervenience of rightness on the base properties would be easily
explained on this view: because rightness is identical to a base
property, on this view, there clearly cannot be a difference in
rightness without some difference in base properties.



If essentialist explanations are legitimate, essentialist reduction
again appears to be a straightforward way of explaining the
supervenience of the ethical. Part of the idea of essence is that
necessarily, nothing can survive the loss of one of its essential
properties. So if rightness had an essentialist real definition purely
in terms of base properties, then it would be clear why there could be
no difference in rightness without a difference in base
properties.



In light of this, neither Hume's dictum nor anti-brutalism
appear to cast doubt on either sort of reductive theory, for both
theories are able to explain supervenience, and hence avoid commitment
to a brute necessary connection between the ethical properties and the
base properties.



Terence Horgan and Mark Timmons claim that even if the ethical realist
endorses reduction, they face a further explanatory burden before they
can fully explain supervenience: "Even if goodness, for
instance, is identical to some specific natural property, there
remains the task of explaining why *this* natural property,
rather than any other one(s), counts as the correct referent of the
term 'goodness'" (1992, 230; emphasis in original).
This is a fair explanatory demand, if we interpret it as the familiar
challenge to provide a plausible theory of reference for ethical terms
(a demand that Horgan and Timmons have pressed incisively). However
this challenge does not appear to have anything distinctive to do with
supervenience. Either the reductive naturalistic realist can explain
the reference of 'wrong,' in which case she can also
explain supervenience, or she cannot explain the reference of
'wrong,' in which case her view is implausible for reasons
that have nothing to do with supervenience.


### 4.2 Functionalist explanations of ethical supervenience



One influential account of metaphysical structure, especially in the
philosophy of mind, has been functionalism. Here is a simplified toy
example of a functional analysis: any system that takes some money as
an input, and reliably produces a candy as an output, thereby counts
as a candy machine. On this account, the kind *candy machine*
is individuated by input-output relations. A *functional kind*
is any kind that can be individuated in this way. Because functional
kinds are not individuated by the nature of the stuff that realizes
the functional relations, they are often claimed to be
paradigmatically friendly to *multiple realization*. Thus,
given my characterization of candy machines, such a machine could be
realized by a structure composed of metal or of plastic or perhaps
even of spooky supernatural stuff. In light of this possibility of
multiple realization, the relationship of functionalism to reduction
is controversial: many philosophers have taken multiple realizability
to constitute a barrier to reduction, but others disagree. (See the
entries on
 functionalism
 and
 multiple realization
 for useful discussion).



Now consider a version of ethical realism that takes ethical
properties to be functional properties. Such a view, like the
reductionist view, appears well-placed to explain the metaphysical
supervenience of the ethical. This is because functional properties
necessarily covary with the class of properties that are their
possible realizers. If, for example, every complex property that could
realize a candy machine is a natural property, then there could be no
"candy machine difference" without a naturalistic
difference. Similarly, if ethical properties are functional properties
that could only be realized by certain of the base properties, then
the supervenience of the ethical on the base properties would be
smoothly explained.


### 4.3 Grounding explanations of ethical supervenience



The strategies for explaining ethical supervenience discussed in the
preceding two sections are useful to *reductionist* and
*functionalist* ethical realists. However, many contemporary
ethical realists reject both functionalism and reductionism about
ethical properties. Most strikingly, several contemporary ethical
realists are *non-naturalists*, claiming that the ethical
properties are a distinct and irreducible class of properties (see the
entry on
 moral non-naturalism
 for discussion). Several philosophers have argued that ethical
supervenience poses a distinctive problem for the non-naturalist
(Dreier 1992, 2019 ; Ridge 2007; McPherson 2012; Vayrynen 2017).
So it is worth asking what metaphysical resources non-naturalists
might have for explaining the supervenience of the ethical.



A salient place to begin is with the *grounding* relation. As
was noted in
 Section 1,
 grounding has recently been theorized as an asymmetrical explanatory
metaphysical relationship (For an introduction to grounding, see the
entry on
 metaphysical grounding;
 for a useful discussion of relevant issues in the context of ethics,
see Vayrynen 2013a). It is thus natural to ask whether the
non-naturalist could explain the supervenience of the ethical on the
base properties by appealing to the fact that: certain facts about the
instantiation of the base properties *fully ground* all facts
about the instantiation of the ethical properties.



A natural question at this point concerns *why* such a
grounding relationship holds. An influential answer is that all
grounding facts are themselves explained in essentialist terms (Fine
1994, Rosen 2010). As
 Section 4.1
 suggested, these essentialist explanations can appear to have
reductionist implications. If so, essentialist explanations are no
help to the non-naturalist.



Stephanie Leary has offered an ingenious proposal within the
essentialist framework: she posits a class of "hybrid"
properties, whose essences entail (i) that they are instantiated just
in case certain base properties are instantiated, and (ii) that
ethical properties are instantiated whenever they are instantiated,
and argues that these relations do not suffice for essentialist
reduction of the ethical (Leary 2017; for critical discussion see
Faraci 2017 and Toppinen 2018).



A recently influential alternative to the essentialist account of
grounding proposes that we can explain the grounding of the ethical in
terms of *metaphysical laws*. Here is the basic idea. One class
of ethical facts are facts which state the instantiation of some
ethical property. An example of such an ethical instantiation fact
would be: *Alice's current state is intrinsically bad*.
One explanation of why the ethical supervenes is that such facts are
always grounded in certain base facts, such as: *Alice is currently
in pain*. The proponent of law-mediated ethical grounding denies
that the latter base fact provides a complete grounding explanation
for the former ethical fact. Rather, a complete grounding explanation
will take this form:



> 
> 
> It requires a base fact (e.g. *Alice is currently in pain*) and
> an ethical law (e.g. *Pain grounds badness*), in order to fully
> ground any ethical instantiation fact (e.g. *Alice's current
> state is intrinsically bad*).
> 
> 
> 



Suppose that, necessarily, every possible ethical instantiation fact
is grounded by the combination of a base fact and an ethical law, as
in this example. Then, (i) this would provide a complete explanation
for supervenience: this grounding structure would explain why the
instantiation of ethical properties must covary with thew
instantiation of base properties. And (ii) this might look like a
promising explanation on behalf of the non-naturalist, since the
ethical laws could be metaphysically fundamental ethical entities. If
ethical laws such as the one mentioned here are metaphysically
fundamental, then one might think that this would secure
non-naturalism (For this reason, Gideon Rosen calls such
metaphysically fundamental laws 'Moorean connections'
(2010, SS13).



The appeal to fundamental laws may seem to raise the same concerns
that a brute supervenience relation did, however: Why is there a
metaphysical law linking these distinct properties? The contrast with
essentialist explanations is striking: in the latter case, facts about
the natures of the related properties explain the links between them.
However, some have argued that metaphysical grounding relations are
either commonly, or even universally, law-mediated (e.g. Kment 2014,
SS6.2.3; Wilsch 2015). For a taste of the currently flowering
literature on the explanatory role of ethical laws or principles, see
(Eliot 2014; Scanlon 2014, Ch. 2; Schroeder 2014; Skarsaune 2015;
SS7; Rosen 2017a; 2017c; Berker forthcoming; and Morton
forthcoming).



This brief sketch of possible types of metaphysical explanations of
supervenience barely scratches the surface. Among the many other
options, replies grounded in appeals to tropes or universals have
garnered explicit attention (Ridge 2007, Suikkanen 2010). As with the
appeal to grounding, a central question about such strategies is
whether they constitute genuine explanatory progress, or whether they
simply explain one necessity by appealing to some further brute
necessity.


### 4.4 Analytic and conceptual explanations of ethical supervenience



This and the next subsection consider attempts to explain the
metaphysical supervenience of the ethical by appealing to conceptual
or ethical premises.



The first such strategy appeals to analytic or conceptual truths.
Suppose that an ethical realist accepts the popular view that ethical
supervenience is an analytic truth. She might put her view this
way:



> 
> **Analytic**
>   
> 
> It is an analytic truth that: if two metaphysically possible entities
> are alike in all base respects, they are alike in all ethical
> respects.
> 



The core idea is that the truth of Analytic explains the truth of the
supervenience thesis that it embeds (Intuitive Metaphysical). On this
account, the ethical and the base properties covary because it is
*definitional* of 'ethical' that nothing could
count as an ethical property unless it covaried in this way. This
strategy claims to meet the bruteness challenge: the necessary
connection is explained by the way a property would have to be, in
order to be what we talk about when we talk about ethical properties
(cf. Stratton-Lake and Hooker 2006).



Consider three brief worries about this strategy. The first is that on
some influential contemporary accounts of analyticity, analyticity
does not guarantee truth. For example, one account of analyticity is
that for a sentence 'S' to be analytic in a language L is
for competence with L to dispose a speaker to accept 'S'.
And some philosophers (e.g. Eklund 2002) have argued that there are
inconsistent sets of sentences that satisfy this condition. If this is
right, Intuitive Metaphysical's being *analytic* in
English would not guarantee its being true.



The second worry is broadly intuitive. Analytic alone does not appear
to guarantee that the supervenience of the ethical *follows*
from the other aspects of the nature of ethical properties. And this
suggests that, for all Analytic says, we can conceive of ethical\*
properties, which have every feature characteristic of ethical
properties, except that they do not supervene. But this may lead us to
wonder: why give the ethical properties the role in our lives that we
do, and ignore the ethical\* properties, just because they do not
supervene? (For a related point, see the end of Mabrito 2005.)



The third worry is that even if the truth of Analytic entails the
truth of Intuitive Metaphysical, it nonetheless arguably does nothing
to *explain* why the supervenience relationship holds. Consider
an analogy: suppose that the infallible oracle tells you that a
certain ethical supervenience thesis holds. This testimony does
nothing to explain why that supervenience thesis holds (compare
McPherson 2012, 221-222, and Dreier 2015, 2019). Like the
oracle's testimony, one might think that learning the truth of
Analytic would simply reinforce our confidence in the very thesis
(Intuitive Metaphysical) that we were hoping to explain.



My exposition of these three worries (like the rest of this entry thus
far) has followed the common practice of lumping together the notions
of *analytic truth* and *conceptual truth*. Terence
Cuneo and Russ Shafer-Landau (2014) have argued that distinguishing
these two notions permits them to develop an attractive form of moral
realism, and also enables them to explain the supervenience of the
moral properties. They distinguish analytic and conceptual truth as
follows: for a *sentence* to be analytically true is for it to
be true in virtue of the meanings of the terms that constitute it. By
contrast, for a *proposition to be a conceptual truth* is for
it to be true wholly in virtue of the essences of its constituent
concepts (ibid., 410-11). Concepts, in turn, are to be
understood as abstract non-mental objects. One has a propositional
thought in virtue of being appropriately related to some of these
objects.



Cuneo and Shafer-Landau then offer what they call a 'reversal
argument', which entails that some conceptual truths about
morality are 'fact-makers': that is, some of the facts
about the distribution of moral properties are grounded in facts about
moral concepts (ibid., 418-421). This puts them in a position to
avoid the complaint that I just made about Analytic: on their view,
conceptual truths really do metaphysically explain (some) of the
relations between the moral and the base properties. They then propose
that such connections quite generally explain the supervenience of the
moral.



It is worth emphasizing the commitments of this ingenious proposal.
Consider one central issue. Cuneo and Shafer-Landau argue for the
existence of several substantive-seeming conceptual truths about
morality. As they admit, their view is quite heterodox in virtue of
this. However, they nowhere claim that *all* necessary moral
truths can be explained as conceptual truths. That, of course, would
be a much stronger claim, and much harder to motivate. However,
Intuitive Metaphysical is a quite general modal covariance thesis, and
in light of this, only the stronger claim would suffice to explain its
truth.


### 4.5 Ethical explanations of ethical supervenience



Several philosophers have suggested that we can offer *ethical*
explanations of the supervenience relation (Kramer 2009, Ch. 10; Olson
2014, SS5.1, Scanlon 2014, 38ff; other philosophers, such as
Dworkin 1996 and Blackburn 1998, 311 also appear committed to this
idea; for discussion see Tiefensee 2014). For example, one might think
that the dictum *treat like cases alike!* is an ethical
requirement of ethical reasoning. Or one might think that all ethical
truths are grounded in certain fundamental ethical truths that are
relational: for example, a fundamental truth might be that it is wrong
to torture someone purely for fun. This truth states a relationship
between ethical and non-ethical properties. If all ethical facts are
explained by such fundamental ethical truths, then these truths could
seemingly explain why there are supervenience relations between
ethical and base properties.



One worry about this strategy is that one might take a mark of ethical
realism to be commitment to a truthmaker thesis, according to which
ethical truths are metaphysically explained by (or grounded in) the
patterns of instantiation of ethical properties. The ethical
explanation strategy seems to invert this intuitive order of
explanation, by having the distribution of ethical properties
explained by ethical truths.



Suppose that we rejected this idea in an especially radical way,
insisting instead on the reverse order of metaphysical explanation
everywhere. The nature of every property, we might say, is wholly
grounded in some relevant subset of the true propositions. Provided
that we can recover the idea of metaphysical explanation within this
framework, we will be able to isolate the set of propositions that
state metaphysically unexplained necessary connections. And it is
natural to think that the brute necessities worry could be expressed
within this framework as objecting to accepting such propositions. The
problem is that *fundamental* normative principles, as invoked
in the 'ethical explanation' strategy, would seem to be of
exactly the objectionable sort.


## 5. Arguments against Ethical Supervenience, or its Significance



As the preceding sections have shown, philosophers have tried to
extract a number of striking conclusions using ethical supervenience
as a premise. Part of the motivation for these attempts is that
ethical supervenience is widely assumed to be a powerful dialectical
weapon, such that if your view is incompatible with ethical
supervenience, it is in trouble. This section considers challenges to
this status.


### 5.1 Arguments against supervenience from thick ethical concepts



It is now common to distinguish thick ethical concepts--like
*courage*--from thin ethical concepts--like
*ought* or *good* (for an introduction to thick ethical
concepts, see Roberts 2017). Courage seems like an ethical concept: we
expect each other to treat courage as a virtue and not a vice.
However, competent use of thick ethical concepts seems to require
recognition that only certain sorts of grounds make an ascription of
such a concept apt. To adapt Monty Python's example, it seems
conceptually inapt to say that Sir Robin was *courageous* in
light of running away from battle, even if we think that is what he
ought to have done.



Jonathan Dancy (1995, 278-9) and Debbie Roberts (2018) have
suggested that attention to thick ethical concepts casts doubt on
ethical supervenience. The core idea is this: it is true that there
are no thin ethical differences between otherwise identical
circumstances. However, it is suggested that sometimes the thin
ethical properties of an action or event are best explained by citing
thick ethical properties. And it is claimed that it is not at all
clear that these thick ethical properties can always be explained in
purely base terms (see especially Roberts 2017a).



A natural objection to this strategy is to point out that the
supervenience of the thick on the base properties is, if anything, far
more plausible than the supervenience of the thin. For example, it is
very hard to believe that two possible worlds could be wholly
base-identical, but be such that Doris's action is brave in the
first world, but not brave in the second.


### 5.2 Arguments against the epistemic credentials of ethical supervenience



Section 2
 noted that there are few extended defenses of ethical supervenience.
This might suggest that the evidence for the supervenience is
overwhelming. However, it might instead be a sign that supervenience
is a dogma, accepted without adequate critical examination. This
section briefly explains two challenges to the epistemic credentials
of ethical supervenience.



Joseph Raz briefly suggests that the supervenience of the ethical does
not purport to explain much. And he suggests that this explanatory
poverty gives us reason to doubt whether the ethical supervenes.
According to Raz, ethical supervenience neither provides more specific
theses that allow us to concretely explain the ethical features of
reality, nor guarantees that we can find such explanatory theses
(2000, 54-5). If we assume that we should accept only those
theoretical claims that do substantial explanatory work, then this
casts doubt on ethical supervenience as a theoretical claim.



Section 2
 suggested a different explanatory case for supervenience than the one
Raz considers: general ethical supervenience theses serve to explain
the host of specific ethical supervenience facts that we notice. These
facts are perhaps not themselves explanatory. But they may seem
difficult to intelligibly deny, at least pending a developed moral
epistemology that might adjudicate their epistemic credentials.



Alison Hills (2009) argues that we can undermine the case for ethical
supervenience by granting that in many cases ethical difference
without naturalistic difference seems *inconceivable*, and
arguing that we should not take inconceivability here to be a good
guide to impossibility. She suggests that the appearance of
inconceivability may be grounded in our unwillingness to engage in
certain distasteful imaginative exercises.



Hills bolsters this case by arguing that if we consider a
controversial and low-stakes case--say, whether a certain lie
made with benevolent motives is permissible--we are able to
conceive of such a lie being either permissible or impermissible. But,
she suggests, if we can conceive of it as being permissible, and as
being impermissible, we have shown that we are able to conceive of two
ethically inconsistent possible worlds. Further, this low-stakes case
is easier to conceive of than the possibility of Hitler being a moral
paragon, and Hills suggests that this supports the idea that
conceivability is grounded in our willingness to imagine certain
possibilities, for we presumably have a stronger desire to avoid
imagining Hitler as a moral paragon than we do to avoid imagining the
lower-stakes case.


### 5.3 Arguments against the strong metaphysical supervenience of the ethical



Section 1.3
 showed that one of the crucial choice-points in theorizing ethical
supervenience is the strength of the modality of the supervenience
relation (conceptual? metaphysical? etc.). And
 Section 3
 and
 Section 4
 showed that the claim that the ethical supervenes with conceptual or
metaphysical necessity is the starting point for several influential
arguments. Gideon Rosen's (2020) develops a view of the modal
strength of ethical supervenience that is intended to be strong enough
to accommodate the intuitive appearances, while weak enough to be
dialectically inert.



The heart of Rosen's challenge is an argument that we can
characterize and clearly regiment a notion of *normative*
necessity, which falls short of metaphysical necessity (i.e. at least
some normative necessities are metaphysically contingent), while still
being quite strong, in the sense that in any counterfactual where one
considers how things would be if we altered some non-normative fact,
we hold fixed the normative necessities. Rosen proposes that normative
necessity is the appropriate modality for ethical supervenience. If he
is correct about this, most of the arguments from supervenience
discussed so far would fail, as they tend to require ethical
supervenience to have either metaphysical or conceptual strength.



Even with this alternative clearly stated, the strong metaphysical
supervenience of the ethical may seem especially plausible. But with
his account of normative necessity in hand, Rosen can make two points:
(i) when we consider possibilities that violate the strong
metaphysical supervenience of the ethical, we are considering *very
distant* possibilities, where our modal judgments may not be
particularly trustworthy, and (ii) our judgments of metaphysical
impossibility of these scenarios might be explained by implicit
confusion derived from the fact that while these scenarios may be
metaphysically possible, they are normatively impossible.



By rejecting strong metaphysical supervenience, Rosen must reject the
Sidgwickian explanatory idea suggested in
 Section 2:
 that ethical supervenience reflects a commitment to rejecting brute
ethical contingency. One worry about Rosen's strategy is that by
embracing such contingency one permits an especially objectionable
form of moral luck (Dreier, 2019). On Rosen's view, there may be
a world that is relevantly non-ethically identical to this one in
which my counterpart is *ethically* quite different: in the
extreme case, it raises the specter that the specific loving attitudes
that I bear towards my child might have been *evil*, or even
just a matter of utter ethical indifference. But it is hard to believe
that I am *lucky* that the very attitudes that I possess count
as commendable rather than awful. (See Lange 2018 for another
important challenge to Rosen's argument).



Anandi Hattiangadi (2018) offers a conceivability argument against the
idea that the ethical supervenes with conceptual or metaphysical
necessity. The core idea is this. Mutually inconsistent ethical
principles each appear to be perfectly conceivable. And in general,
conceivability is a good guide to possibility. But if utilitarianism
and Kantianism, say, are both true in some possible world otherwise
like ours, then the supervenience of the ethical fails.



One worry for Hattiangadi's argument is that there seems to be a
straightforward way to contextualize the relevant conceivability
judgments. Consider an analogy. I cannot remember the atomic number of
plutonium. So it is conceivable to me that plutonium atoms have any of
a fairly wide range of numbers of protons. But I do *not* think
that it is possible both that one plutonium atom has 100 protons, and
that some other possible plutonium atom has 110 protons. If any
plutonium atom has 100 protons, they all do. (This stems from my
empirically-derived belief that number of protons is essential to the
nature of plutonium). Similarly, I can entertain the possibility that
utilitarianism is true, or that it is false. But what is hard to wrap
one's head around is the idea that there might be worlds just
like this one in all base respects, which vary with respect to whether
utilitarianism is true.


### 5.4 Arguments against the dialectical significance of ethical supervenience



This section considers a final possibility: accepting ethical
supervenience, but denying on general grounds that it can play a
significant role in the sorts of arguments discussed in
 Section 3
 and
 Section 4.
 Consider two ways of implementing this idea.



First, recall from
 Section 1.1
 the difficulties of identifying a plausible and uncontroversial
account of what the ethical supervenes on. Nicolas Sturgeon suggests
that one conclusion to draw from these difficulties is that there is
no dialectically significant ethical supervenience thesis. For
example, he accepts the supervenience of the ethical on the natural,
but he suggests that his reasons for accepting it are just his reasons
for accepting ethical naturalism (2009, 61). He argues that
philosophers who reject naturalism are likewise in a position to
reject the supervenience of the ethical on the natural (2009,
62-7).



There are two important potential ways of replying to this argument.
First, one might seek a non-parochial argument for ethical
supervenience, such as the one suggested in
 Section 2.
 However, this might not be fully successful: as noted in
 Section 2,
 discussions of supervenience seem unavoidably to involve
controversial philosophical commitments, for example to various
species of modality or to philosophically interesting conceptual
truths. Second, one might be able to find dialectically effective
parochial arguments. For example, Sturgeon himself seeks to make such
an argument against the non-cognitivist (2009, 83-88). To take
another example, most ethical non-naturalists grant at least the
strong metaphysical supervenience of the ethical on the non-ethical,
which allows the brute necessity challenge posed in
 Section 4
 to have dialectical force against them. However, some philosophers
have suggested that the complaint about brute necessities is itself a
parochial one. For example, Terence Horgan and Mark Timmons (1992,
227) suggest that the objectionability of brute supervenience
connections is a distinctively *naturalistic* commitment. This
thought has been embraced by some non-naturalists. For example, Nick
Zangwill (1997, 509) suggests that the bruteness of ethical
supervenience can simply be embraced.



A second way to deflate the dialectical force of ethical supervenience
is to grant that explaining it is a good thing to do, but deny that
this is a particularly weighty consideration in the context of
theory-choice (compare Enoch 2011, 147-8). The issues here are
far from clear, but it is worth emphasizing two costs to this reply.
First, as Gideon Rosen (2020) points out, embracing brute ethical
supervenience is inconsistent with the essentialist account of
modality discussed above. (Recall that according to this account, all
necessary truths are explained by facts about essences). Because the
essentialist account is one of the most powerful and well-developed
accounts of modality, embracing inconsistency with it offers up a
significant hostage to metaphysical fortune. Second, the avoidance of
brute necessary connections seems to be a central part of metaphysical
methodology. Even if modal structure is not the most fundamental
metaphysical structure, it is typically treated as a good guide to
such structure (Kment, 2015). It is hard to see why this would be so
unless necessary connections disclosed some deeper explanatory
relationship. This suggests that the philosopher who wishes to find in
ethics an exception to this principle may need to provide a clear
methodological reason for doing so.