## 1. Moral Philosophy and its Subject Matter



Hume and Kant operate with two somewhat different conceptions of
*morality* itself, which helps explain some of the differences
between their respective approaches to moral *philosophy*. The
most important difference is that Kant sees law, duty, and obligation
as the very heart of morality, while Hume does not. In this respect,
Kant's conception of morality resembles what Bernard Williams
calls "the moral system", which defines the domain of
morality primarily in terms of an unconditionally binding and
inescapable form of obligation (Williams 1985: 193-94). Kant
believes that our moral concerns are dominated by the question of what
duties are imposed on us by a law that commands with a uniquely moral
necessity. Like most eighteenth-century philosophers, he also believes
that our moral lives are preoccupied with the question of how to be
virtuous over a lifetime, but he defines virtue in terms of the more
fundamental concepts of law, obligation, and duty. By contrast, these
concepts play a role in Hume's understanding, but they are far less
central. For Hume, the broader and somewhat looser notion of
"personal merit" lies at the heart of morality (EPM
9.1.1). Our moral concerns are dominated by the question of which
motives are virtuous, and we answer this question by looking to the
responses of our fellow human beings, who--when viewing things
properly--approve of those motives and character traits that are
useful or immediately agreeable (EPM 9.1.13). These are the terms that
characterize duty and obligation for Hume, rather than the other way
around.



Two other differences are important to note. First, Kant draws a
bright line between moral and non-moral phenomena, such as prudence,
politics, or aesthetics. Morality's normative standards and the
nature of its demands distinguish it sharply from the non-moral. For
Hume, the line between the moral and non-moral is far blurrier. He
frequently assimilates moral judgment to "taste" or
judgments about beauty and deformity (Gill 2007), and he explicitly
argues against the strict separation of moral virtues from other
personal qualities such as a quick wit or even good looks (T
3.3.4-5). According to Hume, the strict separation of moral and
non-moral virtues marks one way in which modern moral thought is
inferior to ancient ethics. He also seems to suspect that it reflects
an unhealthy fixation on responsibility and guilt inherited from
Christianity (Darwall 2013: 8-9).



A second important difference is closely related to the first. For
Kant the moral is distinguished from the non-moral not only by a
special form of obligation but also by its elevation above the rest of
life. Morality itself has a unique status or "dignity", as
does the rational being from whose autonomous will the law springs (G
4:435). The proper response to both is a correspondingly unique form
of reverence or "respect", which morality demands equally
from each of us. Kant believes that in the moral domain we take
ourselves--often only implicitly--to be
"persons", elevated above mere "things" such
as machines or other animals. One of our chief moral concerns is to
protect this status, which requires respecting the rational autonomy
at its source and avoiding behavior or patterns of thought and desire
that dishonor or degrade persons by treating ourselves or others as
mere things. This concern looms large in Kant's conception of
morality, and it has a profound influence on his approach to moral
philosophy (Anderson 2008). We see it, for example, in his discussions
of respect for persons and his characterization of ethical virtue as
"love of honor" (cf. Denis 2014). We see it also in the
priority given to duties to self (cf. Denis 2010a), as well as
Kant's claim that a person throws herself away and makes herself
an object of "contempt" when she lies to herself or
grovels before others, for example (MM 6:420). Hume does not see
things this way. For Hume, the domain of morality is not particularly
pure, special, or elevated. It sometimes shows us at our most
benevolent or most magnanimous, but morality is continuous with the
rest of life, including politics and the pursuit of wealth and status
in modern commercial society. Moral virtue is undoubtedly pleasing to
us, sometimes powerfully so, but it does not command a *unique*
form of respect or reverence. Neither do the rules and ideals of
morality, which spring from the same propensities, ideas, and passions
that drive the rest of human behavior. Notions of honor and dignity
may figure into Hume's view of morality but they are far from
central. Morality has us far more concerned with promoting pleasure
and utility.



Hume and Kant both believe that philosophy should offer a theory of
morality's foundation. When it comes to morality's foundation,
they seem to agree on two things. First, morality's foundation
cannot be found in religion. Second, it cannot be found in
mind-independent facts about the world. Yet they disagree about the
rest of the story. Hume locates the foundation of morality in human
nature, primarily in our emotional responses to the behavior of our
fellow human beings. By contrast, Kant locates the foundation of
morality in the rational nature that we share with all possible finite
rational beings. He argues that morality's foundation lies in
the "autonomy" of the rational will. Kant's notion
of autonomy is one of the more central, distinctive, and influential
aspects of his ethics. He defines autonomy as "the property of
the will by which it is a law to itself (independently of any property
of the objects of volition)" (G 4:440). According to Kant, the
will of a moral agent is autonomous in that it both gives itself the
moral law (is self-legislating) and can constrain or motivate itself
to follow the law (is self-constraining or self-motivating). The
source of the moral law is not in the agent's feelings or
inclinations, but in her "pure" rational will, which Kant
identifies as the "proper self" (G 4:461). A heteronomous
will, on the other hand, is governed by something other than itself,
such as an external force or authority.



These rival conceptions of morality and its foundation correspond to
two very different approaches to moral philosophy. Hume's
approach could be called naturalistic, empirical, or experimental. His
moral philosophy is part of his larger endeavor to provide a
naturalistic explanation of human nature as a whole. Hume's
approach relies on and reflects his philosophy of mind, which is
empirical in its approach. He treats ethics, together with psychology,
history, aesthetics, and politics, as the subject of his "moral
science". Hume often seems more interested in explaining
morality as a natural phenomenon than in setting out a normative
ethical theory, treating moral action as part of the same physical
world in which we explain things in terms of cause and effect (EHU
8.1.20-22). On this view, everything we do is open to empirical
investigation and explanation. In fact, Hume often compares humans
with other animals, tracing the bases of human morality to features of
the mind that human beings and other animals have in common (T
2.1.12).



In sharp contrast with Hume, Kant insists on the need for an *a
priori* investigation of morality's foundation. His detailed
treatment of virtue and moral judgment draws heavily on observations
and ideas about human nature. But Kant makes explicit that morality
must be based on a supreme moral principle, which can only be
discovered *a priori*, through a method of pure moral
philosophy (G 4:387-92). By "pure" or *a
priori* moral philosophy, Kant has in mind a philosophy grounded
exclusively on principles that are inherent in and revealed through
the operations of reason. According to Kant, the *a priori*
approach is required because morality's commands are
unconditional. We could never discover a principle that commands all
rational beings with such absolute authority through Hume's method. An
empirical approach, he argues, can tell us how people do act, but it
cannot tell us how we ought to act. Once equipped with the supreme
principle of morality, however, one still requires an understanding of
human beings in order to apply it (MM 6:217). This is important for
Kant. One can say little about what the supreme moral principle
requires *in concreto* without knowing such things as the sorts
of ends people may be inclined to adopt and the conditions under which
human agency will characteristically thrive or wither. As noted below
and throughout, this is one area of Kant's moral thinking that was
significantly influenced by Hume and his fellow sentimentalists.


## 2. Kant's Relationship to Hume and British Moral Philosophy



Hume exerted a profound influence on Kant's theoretical philosophy.
(See, e.g., Guyer 2008, Kuehn 2017, Kuehn 1987b, and Kuehn 1983.) Kant
reports that his "labor" in the *Critique of Pure
Reason* was fundamentally a response to "that Humean
skeptical teaching" (CPrR 5:32). But the impact of Hume's
moral philosophy was far less direct. On the one hand, Kant's early
ethical writings are filled with positive appraisals of moral sense
theory or sentimentalism, and his own views reveal a significant debt
to this tradition. On the other hand, Kant seems to associate the best
of this tradition with Hutcheson more than with Hume (Kuehn 2001:
182). However, Hume exerted a powerful influence on Kant's
anthropological writings and lectures (Louden 2017), and the
anthropological side of Kant's enterprise shaped his thinking about
the application of *a priori* moral philosophy to real human
beings.



Sentimentalism's positive influence on Kant's work was strongest
during the early part of his career (e.g., Walschots 2017 and Sensen
2017). The influence is most pronounced in two of his published works
from the 1760s. In *Observations on the Feeling of the Beautiful
and Sublime* (1764), Kant notes and analyzes the various feelings
of pleasure or displeasure, and attraction and aversion, people feel
to different traits and temperaments in themselves and others (and to
different types of literature, objects in nature, etc.). His remarks
about morality convey a commitment to some form of sentimentalism,
however idiosyncratic. He claims, for example, that the principles of
morality are "not speculative rules, but the consciousness of a
feeling that lives in every human breast and that extends much further
than to the special grounds of sympathy and complaisance" (OFBS
2.217). He describes this as "the feeling of the beauty and the
dignity of human nature", proclaiming that one can "bring
about the noble attitude that is the beauty of virtue" only when
a person "subordinates" her particular inclinations
"to such an enlarged" feeling of the beauty and dignity of
human nature (OFBS 2.217). Kant advances similar claims in another
work from the period, *Inquiry Concerning the Distinctness of the
Principles of Natural Theology and Morality* (1763), where he
distinguishes between the faculty for representing truth and the
faculty for experiencing the good, identifying the latter with
*feeling*. "Just as there are unanalyzable concepts of
the true," Kant argues, "so too there is an unanalyzable feeling
of the good... One of the tasks of the understanding is to
analyze and render distinct the compound and confused concept of the
good by showing how it arises from simpler feelings of the good" (I
2:299).



Other indications of sentimentalism's influence can be found in
Kant's notes and lectures from that period. For example, in the
announcement of his lectures for the winter semester of
1765-1766, he asserts that "the distinction between good and
evil in actions, and the judgment of moral rightness, can be known,
easily and accurately, by the human heart through what is called
sentiment, and that without elaborate necessity of proofs" (WS 2:311).
In the same announcement, he states his intention to develop and
clarify "the attempts of Shaftesbury, Hutcheson and Hume, which,
though imperfect and defective, have nevertheless come farthest in the
discovery of the first principles of all morality" (WS 2:311).
Similarly, in notes that appear to come from between 1764 and 1768,
Kant writes, "[t]he rules of morality proceed from a special,
eponymous feeling, upon which the understanding is
guided..." (NF 19:93 #6581).



As Kant's views developed over the 1760s, his view of sentimentalism
grew more negative. By the late 1760s, he was arguing that this
tradition could not possibly provide an adequate account of moral
obligation. Morality imposes unconditional requirements, and he became
increasingly convinced that sentimentalism could not explain or
justify such requirements. Arguments for this conclusion became
central to Kant's later writings and lectures. In several works,
Kant creates taxonomies of misguided, heteronomous ethical theories
based on material determining grounds--in contrast to his theory
of autonomy, in which the moral motive constitutes an objective,
formal determining ground (see Wood 2005b [Other Internet Resources];
Irwin 2009: chapters 68 and 71; and Schneewind 2009). Kant
distinguishes among these theories based on their accounts of the
basis of moral obligation or the fundamental moral principle (G
4:441-44; CPrR 5:39-41; C 27: 252-54; M
29:621-25). Such theories may assume either subjective
(empirical) or objective (rational) determining grounds for the moral
principle; and within each of these categories, there are theories
that assume these determining grounds are external, and others that
assume they are internal. Objective, internal grounds include
perfection (e.g., Wolff and the Stoics). Objective, external grounds
include the will of God (e.g., Crusius). Subjective, external grounds
include education (e.g., Montaigne) or civil constitution (e.g.,
Mandeville). Subjective, internal grounds can include physical
feeling, such as self-love (e.g., Epicurus) or self-interest (e.g.,
Hobbes), or moral feeling (e.g., Hutcheson) (CPrR 5:40; C 27:253).
Thus, Kant locates moral sense theories among those theories that
assume a subjective, empirical, internal determining ground of moral
feeling as the principle of morality (cf. M 29:621).



From the *Groundwork* on, Kant's objections to sentimentalism
concentrate on what he takes to be its fatal flaw. No empirical
principles can ground moral laws because such laws bind all rational
beings universally, necessarily, and unconditionally. The authority of
empirical principles, by contrast, depends on contingent aspects of
human nature (G 4:442-43). Furthermore, variance in moral
feelings makes them an inadequate standard of good and evil (G 4:442).
Moral feelings cannot be the source of the supreme moral principle
because the supreme moral principle holds for all rational beings,
whereas feelings differ from person to person (M 29:625). If duty were
grounded in feeling, morality would bind some people (e.g., the
tender-hearted) more strongly than others. Even if people were in
complete agreement regarding their moral feelings, the agreement would
be a contingent matter, and thus an inadequate ground for the moral
law, as Kant understands it. Indeed, if morality were grounded in
feeling, it would be arbitrary: God could have constituted us so that
we would get from vice the pleasurable, calm feelings of approval that
we now (allegedly) get from virtue (M 29:625). So for Kant, the
contingency of the ground of obligation offered by moral sense
theories renders those theories inadequate; only *a priori*
determining grounds will do.



As these criticisms indicate, Kant's mature thinking vehemently
rejects sentimentalism's approach to the foundation of morality. Yet
the influence of Shaftesbury, Hutcheson, and Hume lingered long after
Kant came to believe that morality's true foundation lies in the
autonomy of the will. In his notes, Kant remarks that while moral
sense theories cannot justify our moral judgments, or provide the
standards that should guide them, such theories do offer compelling
empirical explanations of how we actually judge action (NF 19:117
#6626). In the same vein, he suggests that even if one rejects moral
sense "as a principle for the judgment of moral action,"
one might still accept it as a theory "of the mind's
incentives to morality" (M 29:625). Kant also continues to
endorse some version of his earlier claim in *Observations*
that some of our feelings indicate a "susceptibility of the soul
which... makes it fit for virtuous impulses" (OFBS 2:208).
We see this in the *Metaphysics of Morals*, for instance, where
Kant claims that moral feeling, conscience, love of one's
neighbor, and self-respect all "lie at the basis of morality, as
*subjective* conditions of receptiveness to the concept of
duty" (MM 6:399; see Guyer 2010). The lingering influence of
sentimentalism can also be seen in his emphasis on the obligation to
"sympathize actively" with others, and in the claim that
we have "an indirect duty to cultivate the compassionate natural
(aesthetic) feelings in us, and to make use of them as so many means
to sympathy based on moral principles and the feeling appropriate to
them.... For this [compassion] is still one of the impulses that
nature has implanted in us to do what the representation of duty alone
might not accomplish" (MM 6:457).


## 3. Reason and Emotion in Morality



Kant, as discussed above, underwent a decisive change of mind about
the views of Shaftesbury, Hutcheson, and Hume. Early in his career, he
endorsed core aspects of their approach, but Kant's mature work
is organized around the idea that *reason*, rather than feeling
or emotion, is the highest authority in the moral domain. In this
respect, many features of his moral philosophy are fundamentally
opposed to Hume's. We can see this opposition in their
respective accounts of moral judgment and moral motivation. A careful
look at these topics, however, also highlights sentimentalism's
residual influence on Kant.



According to Hume, moral judgments typically concern the character
traits and motives behind human actions. To make a moral judgment is
to detect, by means of a sentiment, the operation of a virtuous or
vicious quality of mind. The sentiment here is a
"peculiar" kind of feeling--namely, a feeling of
approval (love, pride) or disapproval (hatred, humility) (T 3.3.1.3).
We call the traits that elicit our approval "virtues", and
those that elicit our disapproval "vices". Sentiments of
approval and disapproval are passions, but they tend to be "soft
and gentle" and therefore easily mistaken for thoughts or ideas
(T 3.1.2.1). The real story is that "morality... is more
properly felt than judg'd of" (T 3.1.2.1). Reason and
experience are required for determining the likely effects of a given
motive or character trait, so reason does play an important role in
moral judgment. Yet reason's role is subordinate. It is one
thing to say that a given trait tends to be useful or conducive to
pleasure and quite another to say that it is "good" or
"virtuous". The moral value of a trait is conferred by the
sentiment of approval, which "gilding and staining all natural
objects with the colours, borrowed from internal sentiment, raises, in
a manner, a new creation" (EPM App. I.21). Hume argues, however,
that only those sentiments experienced from a "general point of
view" count as genuinely moral (T 3.1.2.4). For example, a
person might hate or envy the courage of her enemy but this is not
necessarily a *moral* response. The moral sentiment is
experienced when she considers her enemy's courage from a
"general point of view" (T 3.1.2.4). When a person
considers things from this point of view, she looks upon them as a
"judicious spectator", who is disinterested but still
emotionally responsive to the scene she beholds (Cohon 2008:
126-58). Rather than eliminating her sentiments, the judicious
spectator enlarges them by means of sympathy, which enables her to
resent the misery of others or rejoice in their happiness. (On
sympathy, see Owen 2009 and Taylor 2015: 189-94.)



Kant offers a very different account of moral judgment. He focuses on
the first-person judgments an agent (not a spectator) must make about
how to behave. In his view, the primary question is what the moral law
permits, forbids, or requires. Passion or sentiment cannot answer such
a question. Instead, answering it requires an operation of
*reason* by means of which the agent determines whether her
principle or "maxim" of conduct conflicts with the moral
law. Because she is an imperfect and finite rational being, the law
presents itself to her as a "categorical imperative" (CI).
It is an imperative because it commands and constrains us; it is
categorical because it commands and constrains us with ultimate
authority and without regard to personal preferences or any
empirically contingent ends (G 4:413-20). The two best known
formulations of the CI are the formula of universal law (FUL), which
commands, "*act only in accordance with that maxim through
which you can at the same time will that it become a universal
law*" (G 4:421), and the formula of the end in itself (FEI),
which commands, "*So act that you use humanity, whether in
your own person or in the person of any other, always at the same time
as an end, never merely as a means*" (G 4:429). Scholars
disagree about the relationship between these two formulations of the
CI, as well as their relationship to the other formulations Kant
provides. There is also disagreement about whether FUL or FEI has
primacy in deliberation and moral judgment. Kant claims that FUL is
the standard everyone actually employs in moral judgment (G 4:402;
CPrR 5:69), and some scholars defend its primacy (e.g., Engstrom
2009). Others argue in favor of FEI, emphasizing, in particular, its
role in the *Metaphysics of Morals*, where FEI seems to play
the fundamental role in guiding judgment about specific ethical duties
(e.g., Wood 1999).



Some passages from Kant's work seem to suggest that moral
judgment requires no experience, no knowledge of human nature and
local custom, and no emotional sensitivity. A rational being equipped
with the correct formal procedure has all she needs. Yet such passages
are misleading when read in isolation. This is not Kant's view
of how human beings do, or even should, make moral judgments (Wood
2008: 56). First, application of the CI typically requires auxiliary
or subordinate "principles of application", which must be
taken from our empirical knowledge of human nature (MM 6:217). Second,
Kant frequently emphasizes that no formal procedure could specify all
the principles for applying higher-order principles. Principles of
application help us apply higher order principles to concrete
circumstances, but there is no substitute for experience and
"judgment", which is a knack or uncodifiable talent
(A138/B172). The need for judgment explains why the practice of
casuistry is "woven into ethics" (MM 6:411). Furthermore,
the wider the duty, the more latitude for individual judgment and
experience (MM 6:390). Finally, Kant believes that moral judgment
requires emotional sensitivity and an understanding of social
convention. For example, without these, one might be unable to
determine whether a particular act of beneficence is more
condescending than kind (MM 6:453), or to prevent friendly banter from
sliding into disrespectful mockery (MM 6:467). Proper moral judgment
in such circumstances requires attunement to the feelings of others,
but also facility with the social conventions that shape the dynamics
of personal interaction.



Kant and Hume fundamentally disagree on the question of reason's
authority. Hume assigns reason to a subordinate role, while Kant takes
reason to be the highest normative authority. However, it is important
not to misunderstand the nature of their opposition. Hume offers an
empirical explanation of the moral judgments made in "common
life", which he takes to be part of his broader science of human
nature. This is his focus. By contrast, though Kant makes observations
about the "common" use of reason in morality (e.g., G
4:399), this is not his focus. He says relatively little about what is
going on in our heads or the surrounding social environment when we
make moral judgments. As noted above, Kant at least entertained the
possibility that sentimentalism provides the best empirical
explanation of our patterns of approval and disapproval (NF 19:117
#6626). What Kant insists on is that such responses can be justified
only by pure reason, which is the only faculty capable of
understanding the unconditional necessity of the moral law's
commands. Emotion or feeling plays a crucial role in guiding our
application of the law to particular maxims in concrete circumstances,
but feeling's role is fully subordinate to reason's
(Sensen 2017: 135-137).



A similar contrast between Hume and Kant can be found in their
respective accounts of moral motivation. Hume famously claims that
"Reason is, and ought only to be the slave of the passions, and
can never pretend to any other office than to serve and obey
them" (T 2.3.3.4). The claim is not that reason has no role in
human action, but rather that its role is entirely subordinate to
passion. Hume offers three main arguments for this claim in *A
Treatise of Human Nature*. There is considerable debate about how
these arguments work, the precise nature of Hume's famous
anti-rationalism, and whether his position changed from the
*Treatise* to the second *Enquiry*. (See, e.g., Milgram
1995; Radcliffe 1997 and 2018; Cohon 2008: chapters 2 and 3; and Irwin
2008: chapter 26.)



According to the first argument, "reason alone can never be a
motive to any action of the will" (T 2.3.3.1). Abstract (or
demonstrative) reasoning, which involves *a priori* inferences
and judgments pertaining to relations of ideas, cannot influence the
will, but only assist us in our pursuit of an end we already have. For
example, probable reasoning helps us discover causal relations among
objects of experience conducive to the realization of pre-selected
ends, but such information about cause and effect can never motivate
action on its own: "It can never in the least concern us to
know, that such objects are causes, and such others effects, if both
causes and effects be indifferent to us" (T 2.3.3.3). In order
to be motivated to act, we must first anticipate pleasure or pain from
something. That anticipated pleasure or pain gives rise to feelings of
desire or aversion for the object in question. Probable reasoning
allows us to discern the causes of this object; our positive or
negative feelings about the object then spread to the causes of it;
and we are then motivated to pursue or to avoid them. Simply believing
that one thing causes another will not motivate action (T
2.3.3.2).



A second argument, which builds on the first, aims to show that reason
"can never oppose passion in the direction of the will" (T
2.3.3.1). The only thing that can oppose an impulse to action
generated by one passion is a contrary impulse. Reason, then, could
counteract an impulse to action generated by a passion if and only if
reason could itself generate a contrary impulse. But from the first
argument, we know that that reason cannot generate such an impulse.
"Thus it appears, that the principle, which opposes any passion,
cannot be the same with reason, and is only called so in an improper
sense" (T 2.3.3.4). Hume goes on to say that whatever we feel in
us running contrary to an impulse to act that we mistake for reason
must be something else, such as a calm passion (e.g., a general
appetite for the good, benevolence, or aversion to evil; T
2.3.3.8).



The third argument claims that a passion is an "original
existence", not an idea, or a mental copy of another object.
Contradiction to truth and reason "consists in the disagreement
of ideas, consider'd as copies, with those objects, which they
represent" (T 2.3.3.5). Therefore, a passion cannot be contrary
to truth and reason. Passions cannot, strictly speaking, be evaluated
as reasonable or unreasonable, despite our practice of calling
passions unreasonable or irrational when they depend in some way on
poor reasoning or false beliefs. Later in the *Treatise*, Hume
extends this argument to volitions and actions as well (T 3.1.1.9). We
might view Kant's conflict in conception and contradiction in
will tests of the formula of universal law to constitute refutations
of the latter argument (G 4:421-24; see Guyer 2008: ch. 5).



Hume draws important anti-rationalist moral conclusions from this line
of thought. One obvious implication is that reason cannot be the
motive to moral action; if reason cannot motivate *any* action,
it cannot motivate moral action. A second further conclusion is that
morality and its basic principles cannot be grounded in reason. This
one follows both from his views about the "inertness" of
reason generally, and from his assumption that morality has real
motivational power: "Morals excite passions, and produce or prevent
actions. Reason of itself is utterly impotent in this particular. The
rules of morality, therefore, are not conclusions of reason" (T
3.1.1.6).



Kant never directly addresses the above arguments, but he clearly
rejects Hume's claim that reason is motivationally
"impotent" or enslaved to the passions. It is a central
feature of his moral philosophy that pure reason can be
"practical"--that reason can "of itself,
independently of anything empirical, determine the will" (CPrR
5: 42). He says of right actions that they "need no
recommendation" from emotion or personal inclination. Such
actions "represent the will that practices them as the object of an
immediate respect, and nothing but reason is required to
*impose* them upon the will" (G 4:435). Moreover, in the first
section of the *Groundwork*, Kant repeatedly emphasizes the
special form of "moral worth" that attaches to right
actions that are performed simply because they are right--i.e.,
actions motivated from "from duty" or "from respect
for the law" (G 4:396-401; see Timmermann 2009a).



Despite his emphasis on the motivational efficacy of pure reason,
Kant's discussion of respect makes clear that feeling plays an
important role in human moral motivation (see Guyer 2008: ch. 5; and
Guyer 2010). Early in the *Groundwork*, Kant describes respect
in a manner that makes it sound like a felt aspect of the law itself:
"an action from duty is to put aside entirely the influence of
inclination, and with it every object of the will; hence there is left
for the will nothing that could determine it the except objectively
the *law* and subjectively *pure respect* for this
practical law" (G 4:400). However, his subsequent account makes
respect sound more like a separate feeling that arises from
reason:



> 
> 
> But although respect is a feeling, it is not one received by means of
> influence; it is, instead, a feeling *self-wrought* by a
> rational concept and therefore specifically different from all
> feelings of the first kind, which can be referred to inclination or
> fear. What I cognize immediately as a law for me, I cognize with
> respect, which signifies merely consciousness of the subordination of
> my will to a law without the mediation of other influences on any
> sense. Immediate determination of the will by means of the law and the
> consciousness of this is called *respect*, so that this is
> regarded as the *effect* of the law on the subject, and not as
> the *cause* of the law. (G 4:401 n; also see 460)
> 
> 
> 



Even though we cannot know (or "make intelligible a
priori") how a thought or judgment about the morality of an
action "can itself produce a sensation of pleasure or
pain", Kant thinks that this somehow does happen; it must, if
moral considerations are to be motivating in beings like us. The
phenomenology of respect is unusual, as it involves both pain and
pleasure (or something like it). There is the humiliation an agent
feels when the moral law strikes down her self-conceit; but respect
also feels invigorating and ennobling, since the moral law comes from
the agent's own reason and represents her higher self and
vocation (CPrR 5:73).



However one interprets the phenomenology, respect seems to function as
an intermediary between reason and the will. This raises questions
about the consistency of Kant's view, since he argues repeatedly
that pure reason can, and should, determine the will
"immediately". For this and other reasons, scholars are
divided on how to interpret Kant's treatment of respect.
According to an "intellectualist" line of interpretation,
respect is the *effect* of pure reason's motivational
influence on the will. In other words, we grasp the law by means of
reason, are moved to act accordingly, and feel respect as a result of
being so moved. According to an "affectivist" approach,
however, respect is the proximate *cause* of reason's
influence on the will. In other words, our rational grasp of the
law's demand produces a feeling of respect or reverence, which
then moves the will (or higher faculty of desire). Vexingly, both
interpretations have a strong textual basis and both have been
defended with great skill and insight. (For an excellent discussion of
the issues, see Frierson 2014: ch. 4; see also Sensen 2017, especially
129-134. On the various forms of respect and the different roles
they play, see Williamson 2018.)



In the *Metaphysics of Morals*, Kant argues that additional
feelings also play a role in motivating virtuous conduct. He lists
moral feeling, conscience, love of human beings, and respect (for
oneself) as special kinds of feelings of which we are made aware only
though consciousness of the moral law (MM 6:399). Kant describes these
as "moral endowments" that "lie at the basis of
morality" or the "*subjective* conditions of
receptivity to the concept of duty" (MM 6:399). Since our
compliance with duty presupposes our having these feelings, there is
no duty for us to have them. However, because of their
indispensability to human morality, there is a duty to cultivate them.
Additionally, Kant clearly sees moral value in some sensibly-grounded
("pathological") feelings (MM 6:456-57, 458; also M
29:626; NF 19:77 #6560). Speaking of sympathy, which is perhaps the
best example of this sort of feeling, Kant says "it is... an
indirect duty to cultivate the natural... feelings in us, and to
make use of them as so many means to sympathy based on moral
principles and the feeling appropriate to them" (MM 6:457).



Sympathy allows us better to understand others' needs, helps us
to communicate our concern for them, and can act as an additional
incentive to facilitate our promotion of our happiness helping others.
Such sensibly-grounded feelings can work with rationally-grounded
feelings to motivate action. We may cultivate sympathetic feelings
from respect for the law, and then find these feelings prompting us to
act in certain ways. In this context, where the focus is on virtue,
Kant sounds closer to Hume than he is often taken to be. Indeed,
according to one prominent interpretation, careful consideration of
this and other relevant material highlights at least a few "deep
affinities" between Kant on Hume on motivation and practical
reason (Guyer 2008: 164). Yet the affinities should not be overstated.
Kant's view of sympathy is appreciative but wary, and sympathy for him
does not play the prominent role it plays for Hume. (On Kant's view of
the upsides and downsides of sympathy, see Sorensen 2018. Cf.
Sayre-McCord 2015 on sympathy's role in Hume's theory of moral
judgment.)



Despite several surprising similarities, Kant and Hume clearly
disagree on the basic question of whether pure reason, to use
Kant's expression, can be motivationally efficacious. Kant
thinks it can, while Hume does not. However, one must interpret this
disagreement with care. First, Kant's account of respect makes
clear that feeling or emotion is involved even when pure reason
motivates action. The "affectivist" interpretation of
respect, in particular, suggests that Kant and Hume may agree that
reason cannot motivate action without the intervention of feeling.
(For a similar point about the French and British moral rationalists
Hume probably read, see Radcliffe 2019.) The crucial difference
between them is that Kant believes pure reason capable of producing a
motivationally efficacious feeling (respect), while Hume believes
nothing of the sort. The opposition between them is even starker if
the "intellectualist" interpretation of Kantian respect is
correct. Second, Kant's account of virtue makes it clear that
feelings such as love and sympathy often play an important moral role
in the motivation of human action. Indeed, feelings appear to be
indispensable for human beings and should therefore be cultivated and
strengthened through deliberate practice.



One must also keep track of the level at which these two philosophers
disagree. Consider, for example, the reason why Hume would adamantly
reject Kant's attribution of a special form of "moral
worth" to actions done "from duty". According to
Hume,"*no action can be virtuous, or morally good, unless there be
in human nature some motive to produce it, distinct from a sense of
its morality*" (T 3.2.1.7). To avoid circularity, there must be a
motive to virtuous action that does not itself refer to the moral
goodness of the act (T 3.2.1.4). For Hume, the only time one would
have to rely on one's sense of the goodness of an act to
motivate oneself to do it is when one is deficient in the natural
feelings that ordinarily prompt people to act morally (e.g., natural
affection, generosity, gratitude). The two philosophers do not
necessarily disagree on the *empirical* question of what
actually motivates people. Note that Hume seems to countenance the
possibility of being motivated directly by the sense of an
action's moral goodness. Kant, in fact, seems comparatively
skeptical; he expresses doubt that there have ever been human actions
motivated from duty alone (e.g., G 4:406-407). They disagree
sharply, however, on the *normative* question at issue. Kant
believes that the most morally admirable actions are performed
"from duty" alone. These are the only actions that have
true "moral worth". By contrast, Hume believes that such
actions indicate a character flaw. Indeed, if a person finds she is
moved to act only by the sense that the action is good, she may very
well reproach herself for a lack of generosity or gratitude, for
example, and consequently form a desire to change her character.


## 4. Virtues and Vices



Hume and Kant both treat the concepts of virtue and vice as central to
human morality. But they differ on the basic nature of virtue, and
they offer different catalogues of the virtues and vices. Kant's
discussions reflect his consistent emphasis on freedom, dignity,
rationality, and purity of motive. Hume's reflect his emphasis
on utility, pleasure, and the inherently social nature of the mind.
Correspondingly, the notion of internal struggle is central to
Kant's account, while Hume portrays virtue in comparatively
relaxed and genial terms. Relatedly, Hume is far more comfortable with
the bourgeois virtues integral to successful participation in modern
commercial and political society (cf. EPM 9.1.2). By contrast, Kant is
warier of society's influence on the individual, more insistent
on the need to resist the power of what Rousseau calls
*amour-propre*.



For Hume, the concepts of virtue and vice apply primarily to character
traits or "mental qualities", and secondarily to occurrent
motives and actions. According to Hume, a character trait is a virtue
if, and only if, it "gives to a spectator the pleasing sentiment
of approbation" (EPM App. I.10). Vices, by contrast, are those
traits that generate a displeasing sentiment of disapproval.
Hume's definition builds on his account of moral judgment, and
it makes virtue dependent on the responses of a
"judicious" spectator who contemplates things from a
general point of view. The trait of prudence, for example, is a virtue
*because* it tends to be pleasing to such a spectator. As Hume
puts it, the defining mark of a virtue is that it has the "power
of producing love or pride" when surveyed from the general point
of view (T 3.3.1.3). In other words, a trait is a virtue only insofar
as it tends to provoke the moral sentiment of approval in a properly
situated spectator. If it did not tend to provoke this response, it
would not be a virtue. Note how this marks a significant departure
from Aristotelian conceptions of virtue, which says instead that a
character trait's goodness is a function of the role it plays in
the agent's own flourishing (Cohon 2008: 161).



Hume operates with a capacious catalogue of virtues and vices. His
account in the *Treatise* is organized around the distinction
between "natural" and "artificial" virtues,
which is easily misunderstood. The question is not whether some
virtues are fake or phony and others are authentic. The question is
whether some depend on social conventions and others do not.
Organizing his catalogue by means of this distinction allows Hume to
steer a middle path between those who see morality as entirely
conventional (e.g., Bernard Mandeville) and those who believe it
springs directly from features of human nature that exist
independently of social convention (e.g., Francis Hutcheson).
According to Hume, some virtues do depend on social convention but
others do not (Cohon 2008: 162-163). In both cases, he seeks to
explain why people tend to develop such traits and why they tend to be
pleasing to judicious spectators. Hume drops the artificial-natural
distinction from the second *Enquiry*, but his investigations
there are motivated by the same questions and the resulting view also
steers a middle course between figures such as Mandeville and
Hutcheson.



According to the *Treatise*, artificial virtues include
justice, fidelity to promises, allegiance to government, and chastity.
Hume devotes much discussion to justice, which he treats as a
paramount and paradigmatic artificial virtue. Hume understands justice
primarily as honesty with respect to property or conformity to
conventions of property (T 3.2.2.28). Establishing a system of
property allows us to avoid conflict and enjoy the possession and use
of various goods. The social value of conventions involving property
seems obvious. Yet one reason that justice receives such attention
from Hume is that it poses a problem about moral motivation and moral
approval. Hume claims that there must be a natural (non-moral) motive
for morally good actions. Otherwise they could only be done because
they are morally good, which would be circular, since our judgment of
acts as morally good reflects our approval of the motives and traits
that give rise to the acts in question (T 3.2.1.7, 3.2.1.17). But this
position makes it hard to see how justice can be a virtue; for it is
hard to find the requisite natural, nonmoral motive for it.
Self-interest is the natural motive that justifies our establishing
rules regarding property (T 3.2.2.24); but self-interest is neither
always satisfied by just acts, nor approved in the way that traits we
call virtues generally are (T 3.2.1.9-10). Benevolence cannot be
such a motive either, since it sometimes favors bending or suspending
the rules of justice, and benevolence lacks the power to motivate just
conduct when it's difficult (e.g., T 3.2.1.12). Hume himself says that
"*a* sympathy *with public interest is the source of
the* moral approbation, *which attends that virtue*"
(T 3.2.2.24). But since sympathy with the public interest itself seems
neither nonmoral nor inherent in human nature, this claim redescribes
the problem rather than solves it. Hume must ground sympathy for the
public interest in more obviously natural sentiments, and explain its
development from them (e.g., as self-interest, corrected or redirected
through education or the contrivances of politicians). Otherwise, Hume
must abandon his claim that all morally good actions--even those
associated with artificial virtues--have non-moral, natural
motives. (See Gauthier 1979; Mackie 1980: ch. 5; and Darwall 1995:
302-316.)



The natural virtues are good independently of social convention.
Hume's generous list of natural virtues includes beneficence,
prudence, temperance, frugality, industry, assiduity, enterprise,
dexterity, generosity, and humanity (T 3.3.1.24). In the second
*Enquiry*, he distinguishes among virtues useful to others,
virtues useful to oneself, virtues immediately agreeable to oneself,
and virtues immediately agreeable to others. Among qualities useful to
others are justice, fidelity, honor, allegiance, chastity, along with
the other "social virtues" of humanity, generosity,
charity, affability, lenity, mercy, and moderation (EPM 5.2.44). Among
qualities useful to ourselves are discretion, caution, enterprise,
industry, assiduity, frugality, economy, good sense, prudence,
discernment (EPM 6.1.21). Among qualities contrary to our own
well-being are indolence, negligence, "want of order and
method", obstinacy, fickleness, rashness, and credulity (EPM
6.1.1). Qualities immediately agreeable to oneself include
cheerfulness, tranquility, benevolence, and delicacy of taste.
Qualities immediately agreeable to others include good manners,
politeness, wit, ingenuity, decency, cleanliness, and a graceful or
genteel manner. What holds all these varied traits together as virtues
is their evoking the sentiment of approval in spectators, itself
grounded in sympathy.



Like Hume, Kant takes virtue to be central to human morality. But his
basic conception of virtue differs from Hume's, as does his
catalogue of particular virtues and vices. According to Kant, virtue
is the form in which a being with an imperfect or non-holy will
expresses her supreme commitment to morality. Virtue is such a
being's continually cultivated capacity to master her
inclinations so as to fulfill her duties; a capacity whose cultivation
and exercise is motivated by respect for the moral law (Denis 2006;
Baxley 2010; Wilson 2015a). Several related claims are integral to
Kant's view. First, virtue is a general disposition to do
one's duty out of respect for the moral law (CPrR 5:128, 160; C
27:300). Second, virtue is a kind of strength. More specifically,
virtue is "a moral strength of the will" (MM 6:405) or
"moral strength in adherence to one's duty" (Ant
7:147). Third, virtue presupposes opposition and entails internal
struggle. Virtue's primary opponent is the "radical evil
in human nature"--a propensity to adopt maxims that
prioritize self-love (and inclinations generally) over the moral law
(Rel 6:29, 35-37, 57 n., 58). It is because of radical evil that
virtue implies struggle and demands strength. The fundamental task of
the virtuous person is to achieve the proper ordering of her
incentives, giving the moral law undisputed priority over self-love.
Finally, virtue is moral self-constraint "based on inner
freedom" (MM 6:408), which is the capacity to act on the
autonomously chosen principles of morality, even in the face of
temptation (MM 6:394, 405). Virtue both expresses and promotes inner
freedom. The greater one's moral strength and self-constraint,
the more one acts on reason rather than inclination or impulse (MM
6:382 n).



Kant's catalogue of virtues and vices is organized by his system
of duties. These duties are grounded in the moral law, the supreme
principle of morality, which impresses itself on us as a categorical
imperative. All duties must ultimately derive from this supreme moral
principle. But in the *Metaphysics of Morals*, Kant's
discussion of particular duties of virtue is based more directly on
what he calls the "supreme principle of the doctrine of
virtue". This principle enjoins us to "act in accordance
with a maxim of *ends* that it can be a universal law for
everyone to have" (MM 6:395). As Kant explains,



> 
> 
> In accordance with this principle a human being is an end for himself
> as well as for others, and it is not enough that he is not authorized
> to use either himself or others merely as a means (since he could then
> still be indifferent to them); it is in itself his duty to make the
> human being as such his end. (MM 6:395)
> 
> 
> 



Duties of virtue pertain to the ends, principles, and attitudes of
agents. They aim to protect each agent's inner freedom, and they
cannot be compelled by the state or any other external force. It is
because duties of virtue alone are subject only to internal compulsion
that Kant calls them "directly ethical duties." Among
these duties are the perfect duties to oneself to avoid vices of
suicide, self-mutilation, gluttony, drunkenness, sexual
self-degradation (duties to oneself as an animal and moral being),
lying, avarice, and servility (duties to oneself as a moral being
only); the imperfect duties to oneself concerning the promotion of the
obligatory end of one's own natural and moral perfection, along
with duties to foster self-knowledge, compassion for animals, and
appreciation of the beautiful in nature; the perfect duties to others
to avoid the vices of arrogance, defamation, and ridicule (duties of
respect), and the imperfect duties to promote the end of others
happiness by means of beneficence, sympathy, and gratitude, as well as
by avoiding malice, envy, and ingratitude (duties of love and vices
opposed to them). Kant does not claim to derive these duties from the
categorical imperative or the supreme principle of virtue alone.
Rather, in moving from general principles of morality to moral duties,
he draws on a variety of considerations regarding human nature and
other aspects of the natural world.



Hume and Kant share several influences, so there are unsurprising
areas of overlap. First, like most eighteenth-century philosophers,
both regard the pursuit of virtue as central to human morality.
Second, Kant sides with Hume and Hutcheson against the psychological
egoism associated with Pufendorf, Hobbes, Locke, and Mandeville
(Wilson 2015b; on this debate within British moral philosophy, see
Crisp 2019 and Maurer 2019). Third, they both accept of versions of
Grotius's influential distinction between perfect and imperfect
duties, though their uses of the distinction differ (see Schneewind
1990). Fourth, their respective conceptions of virtue are secular by
historical standards. Neither recognizes duties to God, for example,
and neither counts piety, hope, or monkish self-abasement among the
virtues (e.g., EPM 9.1.3 and C 27:379-80).



Important differences stand out against this backdrop of agreement.
Hume defines virtue in terms of the moral sentiments of a judicious
spectator who views things from a common point of view. Kant, by
contrast, defines virtue in terms of duty, obligation, and law. He
thinks of virtue as moral strength, which is measured by an
agent's ability to defeat those inclinations that oppose the
demands of the moral law (MM 6:405-407). Hume's theory of
virtue has a place for duty and law, but these are not the fundamental
concepts in terms of which everything else must be explained or
justified. Moreover, while Hume certainly recognizes virtues such as
strength of mind, fortitude, and courage, they are not central to his
view of virtue as such. Their status as virtues depends on the moral
sentiments of a judicious spectator, as well as the exigencies and
conventions of a particular age (EPM "A Dialogue".40). For
Kant, such factors are irrelevant to the basic question of what
determines virtue and vice.



A few additional differences are worth noting. First, unlike Hume,
Kant insists on the unitary nature of virtue: "in its Idea
(objectively) there is only *one* virtue (as moral strength of
one's maxims)" (MM 6:447; cf. MM 6:395 and 406). Second,
Hume maintains that the concepts of virtue and vice can apply to
things outside our control, such as traits and motives that spring
involuntarily from our basic temperament. For example, wit, good
memory, and other "mental abilities" are virtues because of their
power to garner the approval of a judicious spectator, even if they
spring from temperament, upbringing, or other factors outside the
agent's control (T 3.3.4.1-5). Kant, by contrast, restricts the
application of virtue concepts to traits, behaviors, and attitudes
that are voluntarily adopted and cultivated as a matter of principle.
Each virtue and each vice has its own maxim (MM 6:404). For example,
being "naturally" witty is not virtuous; neither is cultivating wit
for the sake of social status or power. For Kant, wittiness is not an
ethical virtue unless it is voluntarily cultivated for morally
admirable reasons. Third, Kant and Hume view justice quite
differently. Justice is central to Hume's picture of morality, but
Kant does not treat it as an ethical virtue at all. For Kant, justice
is a matter of right or law (*Recht*), which regulates actions
but not their underlying motives and ends. Furthermore, Hume treats
justice as an "artificial" virtue, but Kant would reject the
artificial-natural distinction altogether. On his view, ethical
virtues are neither artificial nor natural in Hume's sense. Finally,
their conceptions of moral vice are quite different. For Hume a vice
is a mental quality that provokes disapproval from a judicious
spectator. A person's vices do not necessarily say anything
about the quality of her will as a whole or her fundamental attitude
toward the demands of morality. But Kant holds that vice is a
propensity to act contrary to the moral law (Rel 6:37), and it implies
a genuine "*contempt* for moral laws" (C 27:463).
As he puts it, "it is when an intentional transgression has
become a principle that it is properly called a *vice*"
(MM 6:390).


## 5. Freedom and Necessity



Hume and Kant both believe that freedom is essential to morality.
Moreover, both believe that a philosophical theory and vindication of
human morality requires reconciling freedom with universal causal
necessity (determinism). However, they offer different conceptions of
freedom, different ways of reconciling it with necessity, and
different views about why this reconciliation matters for morality.
Scholars agree that Hume is a "compatibilist", but there
is no consensus on the correct label for Kant's position.



Hume defends compatibilism in section eight of *Enquiry concerning
Human Understanding* and Book Two of the *Treatise*
(2.3.1-2). In the *Treatise*, Hume distinguishes between
two conceptions of freedom or liberty: "liberty of
indifference" and "liberty of spontaneity".
According to the idea of indifference, liberty implies "a
negation of necessity and causes" (T 2.3.2.1). For illustration,
consider the Anglican bishop John Bramhall's claim that genuine
liberty is "a liberty from necessity, or rather from
necessitation, that is, a universal immunity from all inevitability
and determination" (1645 [1999: 1]). On this view, a person is
free when, and only when, her action is not necessitated by
*any* antecedent causes. Hume rejects this idea as
unintelligible (T 2.3.1.18) and destructive to morality and religion
(T 2.3.2.5). By contrast, he characterizes spontaneity as that idea of
liberty "which is oppos'd to violence" (T 2.3.2.1).
Therefore, the liberty of spontaneity is freedom from violence, but
not freedom from necessity *per se*. "Violence"
here refers to various forms of unwanted interference with the
execution of one's will, as when a person is forced to sign a
document or locked in a cell from which she wants to escape. These are
cases where we lack the liberty of spontaneity. But a person has such
liberty whenever she is able to do what she wants to do. In such
cases, her actions are causally necessitated, just like any other
event in nature; but they are caused by motives that spring from her
own character. According to Hume, this is the form of liberty at issue
in religion, morality, law, and common life. Hence, spontaneity is the
only form of liberty "which it concerns us to preserve" (T
2.3.2.1).



The liberty of spontaneity, as just described, is perfectly compatible
with causal necessity. There are two main reasons people often believe
otherwise. First, we tend to conflate the two ideas of liberty. In
cases where we enjoy the liberty of spontaneity, our experience
suggests that we also enjoy something more. We recognize, of course,
that "we were influenc'd by particular views and
motives", yet we find it difficult to "perswade ourselves
we govern'd by necessity, and that 'twas utterly
impossible for us to have acted otherwise" (T 2.3.2.1). This is
because "[w]e feel that our actions are subject to our will on
most occasions, and imagine we feel that the will itself is subject to
nothing" (T 2.3.2.2). Yet the assumption that our will is
subject to nothing is a mistake caused by the blind spots of
introspection. An outside observer, whether a friend or a scientist,
"can commonly infer our actions from our motives and character; and
even where he cannot, he concludes in general, that he might, were he
perfectly acquainted with every circumstance of our situation and
temper" (T 2.3.2.2).



The second source of resistance to compatibilism stems from confusion
about necessity. People are prone to think that necessity rules out
liberty because they conflate necessity with compulsion or force. They
believe that when A causes B, A compels or forces B. Hume holds that
this is a mistake, however. Causal necessity is nothing more than the
"constant conjunction" of similar objects and a customary
inference of the mind from the one to the other (EHU 8.1.5). For
example, experience shows that the vibration of a particular string is
constantly conjoined with a particular sound. As a result, the mind
develops the habit of immediately inferring the sound from the
vibration (EHU 7.2.29). We believe that the sound is causally
necessitated by the vibration, but the necessity is a product of the
imagination, which associates the idea of the sound with the
perception of the vibration. This *feeling* that there is a
necessary connection between them is the whole of the matter (EHU
7.2.28). So defined, causal necessity no longer poses an obvious
threat to liberty. It makes sense to follow Bramhall's
definition of liberty as "liberty from necessity" if one
thinks that necessitation involves force or compulsion. But causes do
not force or compel their effects. If one can accept this point, then
a definition like Bramhall's seems less tempting, and necessity
*per se* no longer poses a threat to liberty. The only real
threat is necessitation by external forces, as when a person is forced
to do something she does not want to do.



Broadly speaking, the scholarship offers two ways of interpreting
Hume's compatibilism. According to the most common approach,
Hume's arguments concern the logic of the concepts at issue. On
this reading, Hume analyzes the concepts of liberty and necessity to
show that, properly understood, they do not conflict. We can be
rationally justified in holding a person responsible for her action
even though all human actions are caused. The only question is whether
*she*, rather than some other person or external force, is the
cause of her action. According to Paul Russell's naturalist
approach, however, Hume's view is not primarily a piece of *a
priori* reasoning about the logic of our concepts or the rational
justification of attributions of moral responsibility. Above all it is
an empirical explanation for why we sometimes feel that people are
responsible for their conduct. Hume's concern is with the
cognitive processes that cause such attributions (Russell 1995: ch.
4). He starts with the occasions in common life when we hold people
responsible for their behavior, and then asks, what happens in the
mind on such occasions? On the standard reading, Hume's
treatment of liberty is a fairly self-contained set of compatibilist
arguments, quite detachable from his larger project. On the naturalist
reading, it is deeply connected to his theory of the passions and
moral judgment, which makes it an integral part of his "science
of man."



Hume claims that liberty, understood properly, is "essential to
morality" (EHU 8.31). The above interpretations provide two
different explanations for why this is the case. The standard approach
says that Hume's compatibilism is about the logic of our
concepts and the justification of our judgments. Our judgments about
responsibility entail judgments about the causal antecedents of
action, and such judgments are consistent with determinism. On this
view, the liberty of spontaneity is essential to morality because
attributions of responsibility, which permeate morality (as well as
law and religion), are unjust and unreasonable without it. According
to the naturalist approach, liberty is essential for a different
reason. The naturalist reading emphasizes that, on Hume's view,
attributions of responsibility are made via *feelings* of
approval and disapproval, not judgments (T 2.3.2.6; Russell 1995:
60-4). They are, in his terminology, impressions or sentiments
rather than ideas. These sentiments are partially caused by beliefs
about the source of the behavior to which we are responding. We would
not feel approval or disapproval unless we had been led to think of
the person as the cause of the action. If we believed that her action
was either compelled or uncaused, we would neither approve nor
disapprove of *her*. Our responses or thoughts would be about
something else. Hume's claim, on the naturalist reading, is that
in approving or disapproving of the agent--in feeling gratitude
or resentment, for example--we hold her responsible, and in
holding her responsible we believe that her conduct is free. Hume does
not argue that the latter justifies attributions of responsibility.
His claim is that it causally contributes to such attributions. They
are made by means of feelings of approval and disapproval, which are a
core feature of human morality as we know it. Therefore, the idea of
liberty, properly reconciled with necessity, is essential to
morality.



Like Hume, Kant seeks to reconcile freedom with a commitment to causal
determinism. Yet the two philosophers operate with different
conceptions of causal necessity and very different conceptions of
freedom. For present purposes, it is important to focus on the latter.
Hume concentrates on the liberty of spontaneity, the only idea of
freedom "which it concerns us to preserve". His treatment
looks downstream from the will to its execution in action. A person
has liberty when her action is caused by her will, which Hume equates
with an occurrent motive or desire (T 2.3.1.2). The question of what
ultimately moves the will is irrelevant. Such causes are found in the
person's character and circumstances, and they determine her
will with the same necessity that determines everything else in
nature. Kant, by contrast, looks upstream to what determines the will:
"It is here a question only of the determination of the will and
of the determining ground of its maxims as a free will, not of its
result" in bodily action (CPrR 5:45). One way of putting it is
to say that Hume's account concerns the freedom of action, while
Kant's concerns freedom of the will. Both are concerned with the
freedom of the person or agent, but Kant thinks the person is not
truly free unless her will is free. This is the first point about the
main difference between Kant and Hume.



The second point is that Kant, unlike Hume, believes that the will is
not free unless it can be determined by pure reason. This is why he
repeatedly insists that the main question concerning freedom is
whether pure reason "can be an immediate determining ground of
the will, that is, of the causality of a rational being with respect
to the reality of objects" (CPrR 5:44-45). Furthermore,
Kant holds that this is a question of whether the will can be
determined "independently of anything empirical" (CPrR
5:42). For when pure reason determines the will, the latter's
"ground" must be found in "the intelligible order of
things" rather than in empirical order (CPrR 5:49). This is why
Kant thinks that "the concept of a being that has free
will" involves the concept of a "noumenal" cause
(CPrR 5:55). Note that Kant's idea of noumenal causation is not
equivalent to what Hume calls the liberty of indifference, which
implies a complete absence of causes or necessitation. To appreciate
the point, contrast Kant's view with what Bramhall calls
"liberty from necessitation" or "immunity from all...
determination." Unlike Bramhall, Kant seems to think that the will is
free if, and only if, it *is* necessitated. But the will must
be necessitated by the right sort of thing and in the right way:
namely, by pure reason rather than by an antecedent event whose causal
impact on the will could be described by an empirical law. That is,
the will is free if and only if can be determined by pure reason,
which lies outside the realm governed by empirical laws.



Kant's conception of freedom has profound implications for the task of
reconciling freedom with causal determinism. He maintains that all
events, including human actions, are causally determined by antecedent
events in accordance with empirical laws. But he also seeks to show
that this does not rule out free will (A536-537/B564-565). On
the contrary, one and the same event can be both "a mere effect
of nature" but also an "effect of freedom"
(A543/B571). Kant demonstrates this possibility by distinguishing
between two different "worlds" and arguing that we belong
to both. On the one hand, we belong to the "phenomenal"
world, where all our actions can be explained in terms of antecedent
events (whether physical or psychological). On the other hand,
considered as a "thing in itself", each of us belongs to
the "noumenal" world, which is not subject to "the
temporal order in accord with empirical laws" (A534/B562). We
cannot *know* whether we belong to the noumenal world, but
Kant's theoretical philosophy secures room for this possibility,
and his moral philosophy tries to show that when we become aware of
morality's categorical demands, we think of ourselves as members
of this noumenal or "intelligible world" (G 4:457-58).



We can see here that Kant seeks to reconcile freedom and natural
necessity by means of "transcendental idealism." Indeed, the question
of whether natural necessity rules out freedom is a
"transcendental problem," and only transcendental
philosophy can solve it (A535/B563, A557/B585). The appeal to
transcendental idealism is controversial, of course. Some scholars of
Kant's ethics understand him to be making a metaphysical (or
ontological) claim when he distinguishes between noumenal and
phenomenal worlds (e.g. McCarty 2009). Others understand Kant to be
distinguishing between only different standpoints we take, identifying
the noumenal world with the practical standpoint that we take when we
think of ourselves as autonomous, responsible beings, and the
phenomenal world with the theoretical standpoint we take when we think
of ourselves as part of the natural, deterministic, empirical world
(see Beck 1960: 191-94; Korsgaard 1996a, esp. chs. 6-7).
Both raise concerns. Many find the notion of two worlds metaphysically
cumbersome (at best); but others question whether the two standpoints
approach is robust enough for Kant's purposes. (See Irwin 1984, esp.
37-38; Allison 1990; Guyer 1992: 103-107; and Wood 2005a:
99-100.)



Kant has several reasons for thinking that freedom is essential to
morality. First, freedom is necessary for moral responsibility. When
we hold a person responsible for blameworthy conduct, for example, we
"impute" the ability to have refrained from such conduct
and blame the person for her failure to exercise this ability
properly. The judgment of "blame is grounded on the law of
reason, which regards reason as a cause that... could have and
ought to have determined the conduct of the person to be other than it
is" (A555/B583). Second, Kant holds that "what is
essential to any moral worth of actions is *that the moral law
determine the will immediately*" (CPrR 5:71). If a
person's will were necessitated by her circumstances and
empirical character, as Hume maintains, it would be impossible to
respond properly to the moral law, which demands a kind of purity of
thought and motive that Hume would not countenance. Third, freedom is
essential to morality in that freedom is the ground of a special
status or "dignity" that morality commands us to respect
in ourselves and others. One important but unorthodox line of
interpretation suggests a fourth reason for thinking that freedom is
essential to morality. According to this view, Kant holds (in at least
some places) that freedom is our most fundamental value, the source
from which all other moral value derives. This is "the real
bedrock of Kant's moral thought" (Guyer 2000: 203). On
this view, in fact, we are commanded to obey the moral law because it
"is the necessary means for the realization of human
freedom" (Guyer 2016: 38).



When comparing Hume and Kant, it is a mistake to ask simply which
philosopher has the best account of freedom or does the best job of
reconciling freedom and necessity. They disagree about both causal
necessity and the question of which idea of freedom "it concerns
us to preserve". As a result, they focus on somewhat different
topics. Hume concentrates on what happens downstream from the will,
that is, on how motives determine action. But Kant's attention
is focused on what happens upstream--on the question of what
determines the will. It seems fair to say that from Kant's
perspective, Hume's notion of liberty is thin gruel, no better
than "the freedom of a turnspit" (CPrR 5:97) or the
freedom exhibited by a self-moving clock (CPrR 5:96). It also seems
fair to say that from Hume's perspective, Kant's notion of
free will is, at best, a misguided fiction.



One important question is whether morality requires the sort of
freedom Kant has in mind. Hume would deny that it does, but this is
partly because his view of morality itself is so different from
Kant's. The issue here is not just about free will. It is about
which conception of morality is most plausible. If Kant has convincing
grounds for insisting on the unique nature of moral obligation or
judgments of "moral worth", this puts some pressure on
Hume to take Kant's notion of free will more seriously. Another
important question is how to interpret Kant's actual position,
which is the subject of controversy. Standard textbooks classify Kant
as a libertarian (incompatibilist) about free will, but those who
study Kant most intensively often disagree about the nature of his
view. Some argue that Kant offers a form of incompatibilism (e.g.,
Pereboom 2006; Allison 1990; Watkins 2005), while others maintain that
he is some sort of compatibilist, however unorthodox (e.g., Bennett
1984; Hudson 1994). According to one influential interpretation, Kant
endorses "not only the compatibility of freedom and determinism,
but also the compatibility of compatibilism and incompatibilism"
(Wood 1984: 74). These scholarly debates bear on the question of how
Kant's view compares to Hume's, as does the question of
whether the naturalist or traditional interpretation best captures
Hume's own position. Finally, when comparing Kant and Hume on
the question of freedom, one must recognize that there is a modest and
skeptical side to Kant's view that Hume would applaud. For Kant,
free will is an "inscrutable faculty" (CPrR 5:47), whose
operations lie beyond the reach of human cognition. It is impossible
to *know* whether we actually have free will (CPrR 5:72; G
4:459). Indeed, Kant's significant debt to Hume is evident in
the former's claim that "all human insight is at an end as soon
as we have arrived at basic powers or basic faculties" (CPrR
5:46). Here we find profound agreement between the two philosophers
about the limits of human insight.


## 6. Religion and Morality



Discussions of religious themes can be found in most of Hume's
and Kant's major works. Their treatments of the subject differ
significantly, but they have a few important things in common,
especially on the question of how religion relates to morality. Above
all, both philosophers advocate a secularized approach to moral
philosophy. That is, both argue for the independence of morality from
religion and the importance of keeping the two distinct. They both
express deep concern about the corrupting influence of false religion,
including "enthusiasm" and "superstition". And
they both seek to undermine a good deal of Christian theology,
including traditional arguments for the existence of God. There are
also significant disagreements, however. Generally speaking, Hume is
far more alert to religion's potential costs, such as
intolerance, violence, and distraction from whatever happiness is
available in this life. Kant, by contrast, seems far more attuned to
the benefits of religion, especially its attempts to address the human
need for ultimate answers or consolation in the face of death and
suffering.



On Hume's view, the foundation of morality has nothing to do
with God. This is evident from his distinctive version of
sentimentalism. He argues that morality, much like our aesthetic
responses to beauty, is "founded entirely on the peculiar fabric
and constitution of the human species" (EPM 1.3). This claim is
made in the context of arguing against a form of moral rationalism
that locates the foundation of morality in immutable truths
discoverable by reason (Schneewind 2010). Against rationalists like
Samuel Clarke, Hume claims that morality is a distinctly and entirely
human phenomenon; there are no grounds for believing that human beings
exist in any kind of moral community with God or that God is
answerable to the moral norms that bind us (Schneewind 2010). For
present purposes, there are two additional points to appreciate.
First, Hume's claim entails a rejection of the idea that moral
distinctions between good and evil are instituted by divine command,
as argued by voluntarists such as Pufendorf, Luther, or Calvin.
Second, Hume's version of the above claim differs from the
version found in Hutcheson. On Hutcheson's view, human nature is
essentially good and its goodness reflects the wisdom and benevolence
of God. When we behave virtuously, we further the purposes for which
we were created. Hume, by contrast, rejects Hutcheson's equation
of the natural with the good (T 3.1.2.10), and he rejects his
predecessor's underlying teleology (Gill 2006:
194-208).



Hume frequently draws attention to the moral and political costs of
religion. He never argues that religion is inherently destructive, but
he consistently claims that it tends to distort and corrupt morality.
Were it not for religion's influence, Hume claims, we would
never approve of qualities such as "celibacy, fasting, penance,
mortification, self-denial, humility, silence, solitude, and the whole
train of monkish virtues" (EPM 9.1.3). The "delusive
glosses of superstition and false religion" can cause us to
approve of such qualities despite the fact that they are neither
useful nor agreeable (EPM 9.1.3). Similarly, Hume emphasizes the
difference between moral and religious sources of motivation. When a
person pays a debt or restores a loan, for example, "his divinity is
nowise beholden to him; because these acts of justice are what he was
bound to perform, and what many would have performed, were there no
god in the universe. But if he fast a day, or give himself a sound
whipping; this has a direct reference, in his opinion, to the service
of God. No other motive could engage him to such austerities" (NHR
14.6). Hume often blames these distortions of morality on particular
forms of Christianity, such as Catholicism and sectarian offshoots of
Calvinism and Lutheranism. But in some places Hume comes close to
faulting *any* religion that represents God as
"infinitely superior to mankind" (NHR 10.2), arguing that,
"[t]he more tremendous the divinity is represented, the more
tame and submissive do men become to his ministers" (NHR 14.8).
He clearly believes that monotheistic religions tend to focus human
attention on the one God rather than on the enjoyment of life on
earth. Monotheism also tends to promote intolerance, factionalism, and
even violence.



Like Hume, Kant holds that the foundation of morality is independent
of religion. The main difference between them is that Hume locates
that foundation in human nature, while Kant --depending on the
interpretation--locates it in the structure of practical reason,
the nature of rational beings, or the supreme value of freedom. On
Kant's view, morality is not only independent of religion; it is
also more fundamental. One way that he gives priority to morality is
by arguing that belief in God follows from a moral commitment, and by
denying that recognition of the moral law follows from or must be
grounded in recognition of God's authority. A second way in
which Kant treats morality as fundamental is by denying that we have
any duties to God. All that God commands us to do is what morality
requires: our duties to ourselves and others. A third point is that
Kant insists that children not be taught about religion until they are
familiar with basic moral concepts and principles; otherwise, they may
think, for example, that the reason one should act rightly is to hope
for God's favor and to avoid God's punishment. He argues
that Christianity is superior to other ecclesiastical faiths because
of the centrality of ethics within it from its inception (Rel 6:167).
But all ecclesiastical faiths are liable to corruption, and none is
the ideal form for religion to take. Ideally, we will dispense with
distinct ecclesiastical faiths, along with their revealed texts and
doctrinal statutes and observances, in favor of a universal, pure
religion of reason, dedicated to morality.



While Kant holds that morality's foundation is independent of
religion, the two are more closely connected for him than they are for
Hume. Compared with Hume, Kant is far less antagonistic to religion,
and he consistently tries to preserve a place for religious belief
within the strictures of his moral philosophy. Indeed, this is an
important aspect of his approach to morality. Kant's
"moral theism" is one of his most significant
contributions to the philosophy of religion and the question of
religion's relation to morality. Moral theism is belief in God
founded on morality. By belief (or faith) [*Glaube*], Kant
means something different from knowledge [*Wissen*] (A 822/B
850; WOT 8:140-41). Believing and knowing both involve holding
something to be true. When one knows something, one holds it to be
true on grounds that are "subjectively and objectively"
sufficient, whereas when one believes something, one holds it to be
true on grounds that are subjectively but not objectively sufficient
(A 822/B 850). Here, Kant takes objective sufficiency to imply valid
theoretical grounds, such as evidence or theoretical argument; he
takes subjective sufficiency, by contrast, to imply valid practical
grounds. Thus, belief entails having valid practical reasons for
holding something to be true, while lacking valid theoretical reasons
for doing so. Indeed, when it comes to belief in God, Kant does not
think that knowledge is possible (CPJ 5:471-72).



Kant's position contains a distinctly moral conception of God.
In addition to the attributes of omniscience, omnipresence, and
omnipotence, he ascribes to God the moral attributes of holiness,
benevolence, and justice (LPDR 28:1073-74). God is not only
author and executor of the moral law, but also as its
"personification" (C 27:322; V 27:530, 723; LPDR 28:1076,
1091). Kant also says that all moral requirements can be *seen
as* divine commands (CPrR 5:129; Rel 6:153). God knows and cares
about our virtue and well-being. In particular, he cares about the
realization of the highest good, in which people attain maximal virtue
and, consequently, maximal happiness. This is a God who has created
the world, has incorporated morality into the world, and has a moral
plan for the world (CPrR 5:125; CPJ 5:450). Belief in God allows us to
retain our faith that some of our moral actions will produce the
intended good consequences, and that if we strive our best to promote
the highest good, God will complete the task (C 27:310, 321-22;
CPJ 5:450-53; Rel 6:74-77, 192, 201-202).



The relation between God and the highest good is the basis of
Kant's main argument for belief in God. (See Wood 1970.) The
argument, most clearly articulated in the *Critique of Practical
Reason*, goes like this (CPrR 5:110-14, 124-46). The
moral law issues categorical demands through each agent's own
reason. If the moral law sets forth an end for us to promote, we must
promote it. For our promotion of this end to be rational, the end must
be one that we can rationally view as possible for us to promote
through our own agency. The moral law gives rise to the highest good
(i.e., virtue and conditioned, proportionate happiness), as practical
reason's ultimate end. Thus, we must promote it. Yet it is not
clear that we are capable of effecting the highest good, given the
limitations of our agency and the conditions and workings of the
natural world. If the realization of the highest good is not possible,
however, then we cannot rationally promote it as an end; indeed, we
cannot even make sense of it as an end. But if we do not promote the
highest good, we flout the moral law. Now, suppose that there were a
supreme, eternal, all powerful, all knowing ruler of the universe
(i.e., God); he could bring to completion our imperfect strivings for
the highest good. Thus, if we postulate the existence of God, we can
view the highest good as possible, and can rationally follow
morality's command to promote it. There is no reason not to
postulate God's existence, since his non-existence cannot be
proven, and since belief in him does not conflict with any necessary
beliefs (CPrR 5:135-43). In addition, since belief in God is
necessary for seeing the highest good as possible, we must believe in
God (CPrR 5:125-26, 142-46). Thus, belief in God is
grounded in the necessity of seeing the highest good as possible, and
so for the rational compliance with morality. Thus, Kant says that
belief in God is morally necessary, and that morality leads
ineluctably to religion (CPrR 5:125). We do not, however, have a duty
to believe in God. Postulating God's existence is a theoretical
exercise of reason, which cannot be morally commanded (CPrR 5:125,
144). Rather, our duty to promote the highest good gives rise to
"a need of reason" to assume the possibility of the
highest good. From this need emerges the necessity of postulating
God's existence.



Kant's practical argument differs profoundly from his
contemporaries' speculative or theoretical arguments for God's
existence. His approach grounds the necessity of believing in God in
each person's practical reason, required to "orient
ourselves in thinking" (WOT 8:136-37). According to Kant,
belief in God is "a postulate" of practical reason, that is,
"a theoretical proposition which is not as such demonstrable,
but which is an inseparable corollary of an a priori unconditionally
valid practical law" (CPrR 5:122). Although practical arguments
cannot provide knowledge of God's existence, they can provide
"*moral* certainty" of God's existence (A
828-30/B 856-58; CPrR 5:134, 143; LPDR 28:1011-12).
Moral certainty in God's existence is stronger than the sort of
confidence one could obtain from any theoretical argument.



Hume's influence on Kant regarding the intersection of religion
and morality is evident, though difficult to measure. It is also hard
to tell how much of the influence came directly from Hume's
writings. Hume is not often cited regarding religion in Kant's
major works. Kant's *Lectures on the Philosophical Doctrine
of Religion*, however, suggest familiarity with Hume's
*Dialogues Concerning Natural Religion*, a work which Kant
could have read in its entirety in 1781 (Wood 1978: 14-15), and
perhaps in part when it first came out, since Hamann translated the
first and last parts of it for him (Kuehn 2001: 121). Kant explicitly
discusses Hume's *Dialogues* in the section on the
physiotheological proof, which is what Kant calls the argument from
design (see LPDR 28:1063-4). Furthermore, in the Danzig
manuscript of these lectures, Kant cites Hume within his argument
against the cosmotheological proof (Ak 28:1266; Wood 1978: 83n31).
Kant was clearly also familiar with Hume's *The Natural
History of Religion*. In "A History of Natural Theology,
according to Meiners' *Historia doctrinae de uno vero
Deo*", Kant refers briefly to Hume's account of
polytheists as tolerant in section 9 of *The Natural History of
Religion* (LPDR 28:1125).



Finally, it is interesting to note that many philosophers and other
intellectuals in Konigsberg in the late 1750s and early 1760s
seem to have attributed to Hume a view of religion that has
significant parallels with Kant's mature view. Hamann and others
saw Hume's skepticism as necessary for purging religion of its
traditional arguments and clearing the way for true religion. One
source for this view of Hume is the conclusion of book I of the
*Treatise*, which Hamann translated into German (with some
alterations and excisions to hide its origin) and published
anonymously in 1771 under the title "Night Thoughts of a
Sceptic" (Kuehn 2001: 198-201). Another source is the end
of the *Dialogue*s, where Philo says, "To be a
philosophical skeptic is, in a man of letters, the first and most
essential step towards being a sound, believing Christian" (DR
89). This statement is out of line with Philo's previous
assertions and arguments, and it comes as a surprise at this point in
the text. But, some, including Hamman, take Philo's remark as an
expression of Hume's fideism. Whether the interpretation of Hume is
correct, Philo's remark finds deep resonance in Kant. He is no
fideist, but Kant does hold that purging the traditional "proofs" from
philosophical theology helps us recognize that morality itself offers
a better argument for God's existence -- one which
provides the moral certainty sought by finite rational beings such as
ourselves.