## 1. Life and Career




Moore grew up in South London (his eldest brother was the poet T.
Sturge Moore who worked as an illustrator with W. B. Yeats). In 1892 he
went to Trinity College Cambridge to study Classics. He soon made the
acquaintance there of Bertrand Russell who was two years ahead of him
and of J. M. E. McTaggart who was then a charismatic young Philosophy
Fellow of Trinity College. Under their encouragement Moore decided to
add the study of Philosophy to his study of Classics, and he graduated
in 1896 with a First Class degree in the subject. At this point he
turned his energies towards attempting to follow in the footsteps of
McTaggart and Russell by winning a 'Prize' Fellowship at
Trinity College which would enable him to continue the study of
philosophy there. In 1898 he was successful and over the next six years
he matured as a dynamic young philosopher, actually leading Russell
away from the idealist philosophy of McTaggart and others which was
then dominant in Britain.




Moore's Fellowship ended in 1904; after a spell away from Cambridge,
Moore returned there in 1911 to a lectureship in the University and he
then lived there for the rest of his life (apart from an extended visit
to the U.S.A. in 1940-44). In 1921 he became editor of *Mind*,
the leading British philosophical journal, and in 1925 he became a
Professor at Cambridge. These two appointments confirmed his position
as the most highly respected British philosopher of the time, and with
Wittgenstein back in Cambridge after 1929, Cambridge became the most
important centre of philosophy in the world. Moore retired as Professor
in 1939 (to be succeeded by Wittgenstein) and as editor of
*Mind* in 1944; these retirements marked not only the end of his
pre-eminence, but also of the golden age of Cambridge philosophy.




Early in his time in Cambridge Moore became friends with some of the
young men who went on to form the 'Bloomsbury Group', such
as Lytton Strachey, Leonard Woolf and Maynard Keynes. Through these
friendships Moore exerted an indirect influence on British
twentieth-century culture as profound as that of any more
'engaged' philosopher. These long-lasting friendships bear
witness to Moore's Socratic personality and thus to a side of his
character which his writings do not convey. Gilbert Ryle, the Oxford
philosopher who was Moore's successor both as editor of *Mind*
and as the dominant British philosopher after 1945, emphasized this
side of Moore's personality:



> He gave us courage not by making concessions, but by making
> no concessions to our youth or our shyness. He treated us as corrigible
> and therefore as responsible thinkers. He would explode at our mistakes
> and muddles with just that genial ferocity with which he would explode
> at the mistakes and muddles of philosophical high-ups, and with just
> the genial ferocity with which he would explode at mistakes and muddles
> of his own. (Ryle 270)


## 2. The Refutation of Idealism




Moore was first drawn to philosophy through contact with McTaggart
and under McTaggart's influence he fell briefly under the spell of
British idealism, especially the work of F. H. Bradley. Thus when in
1897 he made his first attempt to win a Prize Fellowship at Trinity he
submitted a dissertation on 'The Metaphysical Basis of
Ethics' in which he acknowledges his indebtedness to Bradley and
presents an idealist ethical theory. One element of this theory is what
he calls 'the fallacy involved in all empirical definitions of
the good', which is immediately recognisable as a precursor of
his famous claim in *Principia Ethica* that there is a fallacy,
the 'naturalistic fallacy', in all naturalistic definitions
of goodness. This point indicates that although, as we shall see below,
Moore quickly came to reject the idealist philosophy of Bradley and
McTaggart, he held that their criticisms of empiricism, as represented
by J. S. Mill's philosophy, were sound and he carried this hostility to
empiricism forward into his mature philosophy. In this respect,
therefore, his early idealist enthusiasm had an enduring impact on his
thought.




A substantial part of this early dissertation is devoted to a
critical discussion of Kant's moral philosophy, and it is striking that
although in his general approach and conclusions Moore endorses the
kind of idealism advanced by Bradley, he is already critical of Kant's
conception of practical reason. He argues that Kant's use of this
conception blurs the distinction between 'the psychological
faculty of making judgments and inferences' and that which is
'true and objective'. This distinction, Moore maintains,
'cannot be either done away or bridged over'. Hence, he
argues, Kant's conception of morality as founded on *a priori*
principles of practical reason is untenable. It is easy to see how this
line of thought could be extended to a general criticism of Kant's
conception of the *a priori*; and it is precisely this
generalisation that Moore undertakes in his successful 1898
dissertation. At the same time he comes to see that his previous
enthusiasm for Bradley's idealism was not well founded (though it still
takes him a little time to accept that the arguments of Bradley and
McTaggart against the reality of time are flawed). So it is in this
1898 dissertation that Moore turns decisively against idealist
philosophy, both in its Kantian and Bradleian forms.




There are several aspects to this. As I have indicated, he rejects
Kant's conception of the *a priori* as a muddled form of
subjectivism or psychologism. The following passage from *Principia
Ethica* (1903) is indicative of his polemic which can be found in
many of his writings of this period:



> That 'to be true' *means*  to be
> thought in a certain way is, therefore, certainly false. Yet this
> assertion plays the most central part in Kant's 'Copernical
> Revolution' of philosophy, and renders worthless the whole mass
> of modern literature, to which that revolution has given rise, and
> which is called Epistemology. (*Principia Ethica*
> 183)




The distinction Moore is drawing on here between thought on the one
hand and what is objective or real on the other is one that runs
through his critique of idealism. An important early context in which
he elaborates it is his discussion of meaning in his famous paper
'The Nature of Judgement' (1899), which comes largely from
his 1898 Dissertation. Moore begins here by attributing to Bradley a
quasi-empiricist view of meaning as abstracted from the total content
of judgement. This is a mistake, but what is important is what follows:
as against this view Moore holds that meanings, which he calls
'concepts', are entirely non-psychological. They come
together in propositions, which are the 'objects' of
thoughts and, as such, are to be sharply distinguished from any mental
contents or representations. Indeed true propositions do not represent
or correspond to a fact or real state of affairs; instead they just are
facts. He put this point very clearly in a short entry written a year
later on 'Truth':



> it seems plain that a truth differs in no respect from the
> reality to which it was supposed merely to correspond: e.g. the truth
> that I exist differs in no respect from the corresponding reality
> -- my existence. So far, indeed, from truth being defined by
> reference to reality, reality can only be defined by reference to
> truth. ('Truth' 21)




As Moore came to see ten years later, this radical metaphysics of
true propositions is too simple. But in the present context what is
striking about it is the way in which by itself it hovers between
idealism and realism. If propositions are thought of as contents of
judgment, then to hold that reality just comprises true propositions is
to take an idealist stance. What makes the position realist in Moore's
hands is his uncompromising realism concerning propositions and
concepts: although they are possible objects of thought, Moore writes,
'that is no definition of them'; for 'it is
indifferent to their nature whether anybody thinks them or not'
('The Nature of Judgment' 4)




Moore's most famous criticisms of idealism are contained in his
paper 'The Refutation of Idealism' (1903). The basic theme
of this paper is the extension to sense-experience of the strong
distinction between the mind and its objects which we have encountered
in connection with meaning. Moore concentrates here on the case of a
'sensation of blue' and maintains that this experience is a
kind of 'diaphanous' consciousness or awareness of blue,
which is not a 'content' of experience at all, but
something real whose existence is not dependent on experience. His
argument here is in part phenomenological: 'when we try to
introspect the sensation of blue, all we can see is the blue'
(41); but he also argues that to suppose otherwise, that the
'blue' is merely a content of the experience is to suppose
that it is a quality of the experience, so that the experience is blue
in much the way in which a blue bead is blue, which he takes to be
absurd. Not surprisingly Moore's critics were not happy with this
comparison, but it was not until the formulation of the
'adverbial' theory of experience by Ducasse in the 1940's,
according to which someone who has a sensation of blue is someone who
'senses bluely', that there was a reasonably robust
response to Moore's criticism. What is, nonetheless, odd about Moore's
paper is that he makes no attempt to address the famous 'argument
from illusion'. Moore concludes that '"blue" is
as much an object, and as little a mere content, of my experience, when
I experience it, as the most exalted and independent real thing of
which I am ever aware' (42). As he was soon to realise, more
needs to be said to handle cases in which something which is not in
fact blue looks blue.




The final aspect of Moore's critical response to idealism concerns
his rejection of the monism which was characteristic of British
idealism. This is the holistic thesis that ordinary things are
essentially inter-related in such an intimate way that they constitute
together an 'organic unity' which is, in a sense, the only
thing that 'really' exists, since it is the only thing
whose existence is not dependent on the existence of anything else.
This thesis is especially characteristic of Bradley's idealism,
according to which the Absolute is the one real thing. In his early
writings and in *Principia Ethica* Moore engages in a good deal
of polemical criticism of this thesis, but it is hard to find any
arguments against it, as opposed to a robust affirmation of a realist
pluralism. Rather later, however, in his paper 'External and
Internal Relations' (written in 1919) Moore focused on the
idealist conception of internal relations which lies at the heart of
the monist thesis. Moore's argument against the thesis that all
relations are internal starts from the claim that the burden of proof
lies on its supporters since it conflicts with our common sense
conviction that things are not essentially inter-related in such a way
that a change to one thing in one respect necessitates changes to
everything else. Moore then argues that the best reason one could have
for the thesis involves a logical fallacy; he shows how the thesis that
all relations are internal might be plausibly, but fallaciously,
inferred from Leibniz' Law, the uncontentious principle that things
which differ in their relations must differ in their identity.
Simplifying a bit, and using Moore's concept of entailment (see below),
his argument runs as follows:


1. Leibniz' Law states that 


> *xRy* entails (*z = x* -
> *zRy*),




where '-' is the truth-functional conditional
2. Since entailment is a necessary connection, one might infer 


> *xRy* - Necessarily (*z = x* -
> *zRy*)
3. From (2) one can immediately infer 


> *xRy* - Necessarily (*x = x* -
> *xRy*)
4. Since *x = x* is itself a necessary truth, one can now infer


> *xRy* - Necessarily (*xRy*)




which expresses the thesis that all relations are internal.




So, on the face of it, this thesis has here been inferred from
Leibniz' Law. Moore observes, however, that the step from (1) to (2) is
invalid; it confuses the necessity of a connection with the necessity
of the consequent. In ordinary language this distinction is not clearly
marked, although it is easy to draw it with a suitable formal
language.




Moore's argument here is a sophisticated piece of informal modal
logic; but whether it really gets to the heart of the motivation for
Bradley's Absolute idealism can be doubted. My own view is that
Bradley's dialectic rests on a different thesis about the inadequacy of
thought as a representation of reality, and thus that one has to dig
rather deeper into Bradley's idealist metaphysics both to extract the
grounds for his monism and to exhibit what is wrong with it.


## 3. *Principia Ethica*




The main achievement of Moore's early period is his book
*Principia Ethica*. It was published in 1903 but was the
culmination of the reflections which Moore commenced in his 1897
dissertation on 'The Metaphysical basis of Ethics'. The
main impetus, however, came from a series of lectures in London on
'The Elements of Ethics' which Moore gave late in 1898.
Moore had the text of these lectures typed up with a view to publishing
them; but as his thoughts progressed he reworked his text and
*Principia Ethica* is the result of this reworking (the lectures
have recently been published as *The Elements of Ethics*). Most
of the first three chapters come from the 1898 lectures; whereas the
last three chapters are largely new material.




In the first three chapters Moore sets out his criticisms of
'ethical naturalism'. At the core of these criticisms is
the thesis that the position involves a fallacy, the
'naturalistic fallacy', of supposing that goodness, which
Moore takes to be the fundamental ethical value, can be defined in
naturalistic terms, in terms, say, of pleasure or desire or the course
of evolution. As against all such claims Moore insists that goodness is
indefinable, or unanalysable, and thus that ethics is an autonomous
science, irreducible to natural science or, indeed, to metaphysics.
Moore's main argument against the possibility of any such definition of
goodness is that when we confront a putative definition, such as that
to be good is to be something which we desire to desire, we can tell
that this is not a claim that is true by definition because its truth
remains for us an 'open question' in the sense that it
remains sensible to doubt it in a way which would not be possible if it
were just a definition which makes explicit our understanding of the
words. The merits of this argument are questionable; in many cases we
can sensibly doubt the truth of a definition, especially where the
definition makes use of discoveries that have not been part of our
ordinary understanding, as is normally the case with definitions in the
natural sciences. But there is, I think, a way of modifying Moore's
argument which takes it around this objection, namely by taking it to
rest on the epistemological thesis that ethical questions cannot be
answered without the explicit involvement of ethical beliefs. The
reason that this thesis is inimical to naturalistic definitions of
ethical values is that an important role of definitions in the natural
sciences and elsewhere is that they enable one to answer questions in
new ways that would not otherwise be possible: it is thanks to the
definition of water as H2O, and not in terms of its familiar
phenotype, that we can be confident that some comets are mainly
composed of water. But there is no way in which we would accept that
the answer to a novel ethical question, for example concerning the
acceptability of the use of human embryos for stem cell research, is to
be found by finding a definition of ethical values which enables us to
answer this question without drawing on beliefs that are expressed with
the familiar ethical 'phenotype', i.e., explicitly ethical
concepts.




This defence of Moore's argument does not address a different
concern, namely that the argument applies only to versions of ethical
naturalism which involve a definition of ethical value, and thus that
naturalist positions which maintain that ethical value is an
irreducible natural property are not touched by the argument. Moore's
argument against positions of this kind rests on the claim that the
ethical value of a situation is not a feature of it which is
independent of its other properties; on the contrary it depends on its
other properties. As he puts it in the preface he composed for the
second edition of *Principia Ethica*, but never actually
published, a thing's 'intrinsic value' depends on its
'intrinsic nature', and he glosses this dependence in terms
of the relationship which we now call 'supervenience'
(though Moore does not use the term): things with the same intrinsic
nature, or natural properties, must have the same intrinsic value (see
'The Conception of Intrinsic Value' 286). Moore took it
that supervenience was not an inherently reductive relationship, and
thus that it was consistent for him to hold that goodness is not a
natural property even though it supervenes upon natural properties;
but, he assumed, if one takes the view that goodness is itself a
natural property, the fact that it supervenes upon other natural
properties makes it impossible to avoid a reductive thesis. So the
supervenience of intrinsic value removes the option of a non-reductive
naturalism without contradicting his version of ethical
non-naturalism.




Subsequent discussion has shown that the relationship between
supervenience and reduction is a complicated matter, and though I think
that Moore's position is defensible this is not the place to take the
issue further. Instead I want to turn to the concept of intrinsic value
which is central to Moore's theory. One aspect of this is easy, namely
the distinction between the 'intrinsic' value of a
situation and its 'instrumental' value: this is the
distinction between the value inherent in a situation and that which
depends only on the situation's consequences. Despite this distinction
it remains the case that intrinsic value is the fundamental type of
ethical value, since instrumental value is definable in terms of the
intrinsic value of a situation's consequences. But intrinsic value is
not merely non-instrumental value; for it is also to be distinguished
from what Moore calls the 'value as a part' of a situation,
namely the extra contribution which the situation makes to the value of
a complex situation of which it is a 'part', over and above
its intrinsic value. This is not a conception which is familiar to us,
but Moore illustrates the point by the following case: although
knowledge has little intrinsic value, the value of the aesthetic
appreciation of a beautiful work of art (which is, according to Moore,
potentially one of the most valuable things there is) is greatly
enhanced by knowledge about it. So this kind of knowledge can have a
substantial 'value as a part' even though it has little
intrinsic value. As before intrinsic value remains the fundamental
conception of value, since a situation's value as a part is defined in
terms of the overall intrinsic value of a complex situation to which it
makes a contribution beyond its own intrinsic value. Nonetheless this
point implies that a thing's intrinsic value is not simply its value
irrespective of its consequences; it is also its value irrespective of
its context. Hence the concept of intrinsic value is to be such that a
type of situation has the same intrinsic value in all contexts --
which is why Moore holds that its intrinsic value depends only on its
'intrinsic nature'.




There are two connected problems here: the first concerns the way in
which something's 'value as a part' depends on accepting
that when it occurs as an element of a complex situation it may affect
the latter's value in a way which is not simply the result of taking
its intrinsic value into account. This judgement is enshrined by Moore
in his 'principle of organic unities', which declares that
this kind of non-aggregative valuation of complex situations is liable
to occur. The problem here is not that Moore's principle is incorrect,
but rather that it seems irrational since it puts a block on moral
reasoning. The second problem concerns the thesis that intrinsic value
is the same in all contexts. For this just seems wrong, in that the
value of, say, friendship differs from one context to another.
Although, as Moore rightly says, friendship is normally one of the most
valuable things there is, it has no value at all where claims of
justice are at stake, as in a court of law. So Moore's conception of
absolutely universal intrinsic values should be replaced by a
conception which allows for the 'bracketing' of normal
values in certain contexts; and once this is in place, along with a
more sophisticated account of normative values than Moore provides, it
is reasonable to hope that the phenomena captured by Moore's irrational
principle of organic unities will find a more comprehensible
interpretation.




Another area where Moore's ethical theory is problematic is his
account of ethical knowledge. Because of his hostility to ethical
naturalism Moore denies that ethical knowledge is a matter of empirical
enquiry. But, as we have seen, he is equally hostile to Kant's
rationalist thesis that fundamental ethical truths are truths of
reason. Instead he holds that ethical knowledge rests on a capacity for
an intuitive grasp of fundamental ethical truths for which we can give
no reason since there is no reason to be given. The trouble with this
is that if we can say nothing to support a claim to such knowledge,
those who disagree with it can only register their disagreement and
pass on; hence ethical debate is liable to turn into the expression of
conflicting judgements which admit of no resolution. In the light of
this, it is not surprising that Moore's ethical theory was regarded as
undermining the cognitive status of morality, and thus that it led
directly to the development of ethical non-cognitivism by those who
were influenced by Moore, such as A. J. Ayer and C. L. Stevenson. Yet
there was another side to Moore's discussion of ethical issues, in
which he found himself arguing against the hedonist thesis that
pleasure is the only thing with positive intrinsic value, despite the
fact that officially he held that no such arguments could be given.
When engaged in this kind of 'indirect' method of argument,
Moore sees himself as seeking to obtain agreement rather than to
establish the truth, though he also acknowledges that from a
first-person point of view there is little difference here. Because
this indirect method is not integrated into his official method of
ethical inquiry, he says little about its presuppositions. But it seems
to me that one can find here the beginnings of a 'common
sense' approach to ethics which is distinctly preferable to his
official appeal to intuitive judgments concerning the relative
intrinsic value of situations of arbitrary complexity.




So far I have discussed Moore's 'metaethics', his views
about the metaphysics of ethical value and the nature of ethical
knowledge. This emphasis reflects the fact that this aspect of Moore's
ethical theory has been most influential; but it is also worth
mentioning briefly some points from his moral theory. Moore presents a
straightforward consequentialist account of the relationship between
the right and the good: the right action is that which will produce the
best outcome. In practice, because it is so difficult for us to
determine by ourselves what is the best outcome, he allows that we
probably do best if we follow established rules; thus Moore ends up
recommending a conservative form of rule consequentialism, for which he
was criticised by Keynes and Russell. Later critics such as W. D. Ross
argued that because Moore subjects our personal responsibilities to the
impersonal test of producing the best outcome his position does not
adequately capture the way in which they arise from our relationships
with particular people; as recent critics put it, Moore's moral theory
is resolutely 'agent-neutral' and for that reason
inadequate as an account of the personal responsibilities which involve
irreducibly 'agent-relative' values.




Finally, in the last chapter of *Principia Ethica*,Moore sets
out his 'ideal' -- a deliberately unsystematic list of
intrinsic goods (such as friendship and the appreciation of beauty) and
intrinsic evils (such as consciousness of pain). Moore's choice of
values is striking: it connects with the 'Bloomsbury' ideal
of life devoted to Art and Love, and excludes social values such as
equality and freedom. The individualism of the resulting morality is
enhanced by the fact that Moore maintains that these intrinsic values
are incommensurable, and thus that the assessment of priorities among
them is inescapably a matter of individual judgment. As Keynes put it,
Moore's ideal was a kind of secular 'religion' - not much
use for public policy but fine for talented individuals who could agree
to differ in their detailed value judgments.


## 4. Philosophical Analysis




By the time Moore returned to Cambridge in 1911 to a lectureship
there, Russell  and Whitehead were finishing off their massive
project of exhibiting the logical foundations of mathematics --
*Principia Mathematica*. Although Moore was neither a
mathematician nor a logical theorist he was one of the first people to
grasp that Russell's new logical theory was an essential tool for
philosophy and offered important new insights. One example of this
concerns the status of propositions, the 'objects' of
thought. As we saw above, in his early work Moore had been emphatic
that propositions are altogether independent of thought and had even
proposed that facts are just true propositions. But as he came to think
more about falsehood in his lectures *Some Main Problems of
Philosophy* of 1910-11, it became clear to him that this
position was a mistake, since the truth of a proposition should not
affect its  ontological status and yet it would be absurd to give
false propositions the status of facts. So he now rejected the view
that facts are just true propositions. On his new view, facts are, as
before, constituted by objects and their properties; but what about
propositions? According to Moore, philosophers talk legitimately of
propositions in order to identify the aspects of thought and language
which are crucial to questions of truth and inference, and in doing so
it may appear that they regard propositions as genuine entities. But,
Moore now holds, this implication is unwarranted: the mistake here is
one of supposing that 'every expression which seems to be a name
of something must be so in fact' (*Some Main Problems of
Philosophy*, 266). Moore does not allude here explicitly to
Russell's theory of incomplete symbols and logical fictions, but it is
clear that this is the kind of position he has in mind. The new logic
enables one to preserve realist appearances without accepting realist
metaphysics.




Yet Moore was not an uncritical follower of Russell. He was critical
of Russell's account of implication in which Russell proposes that the
truth-functional conditional expresses all there is to the logical
relationship of implication between propositions, and introduced
instead the term 'entailment' for this latter relationship
('External and Internal Relations' 90ff.). While
recognising that entailment is closely connected to logical necessity
he came to think that entailment is not just a matter of the necessity
of the truth-functional conditional, thereby setting off a debate about
this relationship which continues to this day. Again, Moore was
critical of Russell's treatment of existence, in particular his denial
that it makes sense to treat existence as a first-order predicate of
particular objects (for Russell, existence has to be expressed by the
existential quantifier and is therefore a second-order predicate of
predicates). While agreeing with Russell that existence is not a
straightforward first-order predicate (so that the logical form of
'Tame tigers exist' is not the same as that of 'Tame
tigers growl'), Moore argued that statements such as 'This
might not exist' make perfectly good sense and that they could
not do so unless the simpler statement 'This exists' also
makes sense ('Is Existence a Predicate?' 145).




Moore's uses of Russell's logic take place in the broader context of
his use of analysis as a method of philosophy. Although Moore always
denied that philosophy is just analysis, there is no denying that it
plays a central role in his philosophy and it is therefore important to
determine what motivates this role. This question is especially
pressing in Moore's case because he rejected the main analytical
programmes of twentieth century philosophy -- both Wittgenstein's
logical atomism and the logical empiricism of the members of the Vienna
circle and their followers such as A. J. Ayer. In the first case, Moore
rejected Wittgenstein's thesis that whatever exists exists necessarily;
as with the idealist thesis that all relations are internal, Moore held
that our common sense conviction that some of the things which exist
might not have done so creates a strong presumption against any
philosopher who maintains the opposite, and that the logical atomist
position does not provide convincing reasons why this presumption
should be overturned. In addition Moore held that it is just not true
that all necessity is logical necessity, as Wittgenstein maintained; in
his early writings, despite his hostility to Kant, he had explicitly
defended the conception of necessary synthetic truths and he did not
change his mind on this point. This point also provides a reason for
his rejection of logical empiricism, since this position famously
includes the thesis that all necessary truths are
'analytic'. But Moore also recognised that his early
criticisms of William James' pragmatism can be applied to the logical
empiricist position. In connection with James, Moore had observed that
where a proposition concerns the past, it may well be that we are in a
situation in which a proposition and its negation are both unverifiable
because there is now no evidence either way on the matter. But, he
argued, it does not follow that we cannot now affirm that either the
proposition or its negation is true, thanks to the Law of Excluded
Middle; in which case it cannot be that truth is verifiability --
contrary both to James' pragmatism and to logical empiricism.




Yet why then did Moore think that the analysis of propositions was
so important? In part his motivation derives from his acceptance of a
principle which Russell had introduced -- that 'every
proposition which we can understand must be composed wholly of
constituents with which we are acquainted' (Russell 91). For this
principle motivates the 'sense-datum analysis' of
perception to which he devoted so much attention and which I shall
discuss in a moment. In addition, when explaining the importance of
philosophical analysis, he emphasized the importance of getting clear
what is at issue in some debate; but an issue which he himself was not
clear about was that of the implications of an analysis. In his early
writings he took the view that in so far as the analysis of a
proposition clarifies it, it also clarifies its ontological
implications; thus he then held it to be an objection to a
phenomenalist analysis of propositions about material objects that the
analysis calls into question the existence of such objects. But he
later took the opposite point of view, maintaining that a phenomenalist
analysis just provides an account of what their existence amounts to.
In between these two positions, in his 1925 paper 'A Defence of
Common Sense' (which I discuss further below), Moore had held
that what the sense-datum analysis of perception shows is that
sense-data are the 'principal or ultimate subject<s>'
(128) of propositions about perception. This remark, I think, reflects
the true importance of philosophical analysis for Moore: its importance
for him is metaphysical in so far as it reveals the
'ultimate' substances which are the subjects of our
ordinary common sense thought and talk.


## 5. Perception and Sense-data




It did not take Moore long to realise that the realist position he
had advanced in 'The Refutation of Idealism' was too
'na*ve' to be tenable; he had to be able to
accommodate 'false' appearances somehow. But the strategy
Moore adopted to deal with this remained true to the basic thesis of
'The Refutation of Idealism' that one should account for
the appearances of things in terms of the properties of the primary
objects of experience, and not the qualities of experiences themselves.
To elaborate this position Moore introduced the term
'sense-datum' to describe these primary objects of
experience:



> But now, what happened to each of us, when we saw that
> envelope? I will begin by describing *part* of what happened to
> me. I saw a patch of a particular whitish colour, having a certain
> shape .... These things: this patch of a whitish colour, and its
> size and shape I did actually see. And I propose to call these things,
> the colour and size and shape, *sense-data* ... (*Some
> Main Problems of Philosophy* 30)




Moore implies here that the colour, shape and size are distinct
sense-data; but he soon revised his terminology so that these are
regarded as properties of the visual sense-datum he 'actually
saw', or 'directly apprehended' as he normally
says.




Once the concept of a sense-datum has been introduced in this way,
it is easy to see that false appearances can be handled by
distinguishing between the properties of sense-data we apprehend and
the properties of the physical objects which give rise to these
sense-data. But what is the relationship between sense-data and
physical objects? Moore took it that there are three serious candidates
to be considered: (i) an indirect realist position, according to which
sense-data are non-physical but somehow produced by interactions
between physical objects and our senses; (ii) the phenomenalist
position, according to which our conception of physical objects is
merely one which expresses observed and anticipated uniformities among
the sense-data we apprehend; (iii) a direct realist position, according
to which sense-data are parts of physical objects -- so that, for
example, visual sense-data are visible parts of the surfaces of
physical objects. The indirect realist position is that to which he was
initially drawn; but he could see that it leaves our beliefs about the
physical world exposed to skeptical doubt, since it implies that the
observations which constitute evidence for these beliefs concern only
the properties of non-physical sense-data, and there is no obvious way
for us to obtain further evidence to support a hypothesis about the
properties of the physical world and its relationship to our
sense-data. This argument is reminiscent of Berkeley's critique of
Locke, and Moore therefore considered carefully Berkeley's
phenomenalist alternative. Moore's initial response to this position
was that the implied conception of the physical world was just too
'pickwickian' to be believable. This may be felt to be too
intuitive, like Dr. Johnson's famous objection to Berkeley; but Moore
could also see that there were substantive objections to the
phenomenalist position, such as the fact that our normal ways of
identifying and anticipating significant uniformities among our
sense-data draw on our beliefs about our location in physical space and
the state of our physical sense-organs, neither of which are available
to the consistent phenomenalist.




So far Moore's dialectic is familiar. What is unfamiliar is his
direct realist position, according to which sense-data are physical.
This position avoids the problems so far encountered, but in order to
accommodate false appearances Moore has to allow that sense-data may
lack the properties which we apprehend them as having. It may be felt
that in so far as sense-data are objects at all, this is inevitable;
but Moore now needs to provide an account of the apparent properties of
sense-data and it is not clear how he can do this without going back on
the initial motivation for the sense-datum theory by construing these
apparent properties as properties of our experiences. But what in fact
turns Moore against this direct realist position is the difficulty he
thinks it leads to concerning the treatment of hallucinations. In such
cases, Moore holds, any sense-data we apprehend are not parts of a
physical object; so direct realism cannot apply to them, and yet there
is no reason to hold that they are intrinsically different from the
sense-data which we apprehend in normal experience. This last point
might well be disputed, and at one point Moore himself considers the
possibility of a distinction between 'subjective' and
'objective' sense-data; but once one has introduced
sense-data in the first place as the primary objects of experience it
is not going to be easy to make a distinction here without assuming
more about experience than Moore at any rate would have wanted to
concede.




Moore wrote more extensively about perception than about any other
topic. In these writings he moves between the three alternatives set
out here without coming to any firm conclusion. From the outside, it
seems clear that what was leading him astray was the sense-datum
hypothesis itself and his reflections on perception can be regarded as
an extended *reductio ad absurdum* of this hypothesis. It was
only towards the end of his career that he encountered in Ducasse's
adverbial theory a serious alternative to the sense-datum hypothesis.
But the adverbial theory provides no easy way of avoiding the
difficulties Moore confronted: Moore rightly objected to Ducasse that
it is not at all clear how the structure of a sensory field can be
construed in adverbial terms. Yet there were other alternatives: in
particular, from the start of the twentieth century the
phenomenological movement had offered an account of perception based
upon a recognition of its inherent intentionality which avoids some of
the pitfalls of the sense-datum theory. It is, I think, a pity that
Moore did not engage with this position, but this detachment was all
too characteristic of the relationship at the time between the
analytical and phenomenological traditions.


## 6. Common Sense and Certainty




An important aspect of Moore's rejection of idealism was his
affirmation of a 'common sense' realist position, according
to which our ordinary common-sense view of the world is largely
correct. Moore first explicitly championed this position in his 1910-11
lectures *Some Main Problems of Philosophy*but he made it his
own when he responded in 1925 to an invitation to describe his
'philosophical position' by setting this out as 'A
Defence of Common Sense'. Moore begins the paper by listing a
large number of 'truisms' such as that 'the earth had
existed also for many years before my body was born'. Concerning
these truisms he then asserts, first, that he knows them for certain,
second, that other people likewise know for certain the truth of
comparable truisms about themselves and, third, that he knows this
second general truth (and, by implication, others do too). So the truth
and general knowledge of these truisms is a matter of common sense.
Having set out these truisms, Moore then acknowledges that some
philosophers have denied their truth or, more commonly, denied our
knowledge of them (even though, according to Moore, they also know
them) and he attempts to show that these denials are incoherent or
unwarranted. These claims might seem to leave little space for radical
philosophical argument. But in the last part of the paper Moore argues
that his defence of common sense leaves completely undecided the
question as to how the truistic propositions which make up the common
sense view of the world are to be analysed; the analysis may be as
radical as one likes as long as it is consistent with the truth and
knowability of the propositions analysed. Thus, for example, he is
content to allow that philosophical argument may show that a
phenomenalist analysis of propositions about the physical world is
correct.




This last point shows that Moore's defence of common sense is not as
much of a constraint on philosophical theory as one might at first have
thought; for philosophical analysis can reveal to us facts about the
'principal or ultimate subject' of a truistic proposition
which are by no means what common sense supposes. This implication is
important when one turns to consider Moore's most famous paper, his
'Proof of an External World' -- the text of a British
Academy lecture delivered in 1939 just when Moore was retiring from his
Cambridge Professorship. Moore here sets himself the task of doing what
Kant had earlier set himself to do, namely providing a proof of the
existence of 'external objects'. Much of the lecture is
devoted to working out what counts as an 'external object',
and Moore claims that these are things whose existence is not dependent
upon our experience. So, he argues, if he can prove the existence of
any such things, then he will have proved the existence of an
'External World'. Moore then maintains that he can do this
--



> How? By holding up my two hands, and saying, as I make a
> certain gesture with the right hand, 'Here is one hand',
> and adding, as I make a certain gesture with the left, 'and here
> is another' ('Proof of an External World'
> 166).




Moore then goes to argue that this demonstration of his hands was a
'perfectly rigorous' proof of the existence of external
objects. For its premises certainly entail its conclusion and they are
things which he then knew to be true --



> I *knew* that there was one hand in the place
> indicated by combining a certain gesture with my first utterance of
> 'here' and that there was another in the different place
> indicated by combining a certain gesture with my second utterance of
> 'here'. How absurd it would be to suggest that I did not
> know it, but only believed it, and that perhaps it was not the case!
> You might as well suggest that I do not know that I am now standing up
> and talking -- that perhaps after all I'm not, and that it's not
> quite certain that I am! ('Proof of an External World'
> 166)




The significance of this performance has been debated ever since
Moore set it out. It is commonly supposed that Moore here sets himself
to refute philosophical skepticism; and that his performance, though
intriguing, is unsuccessful. But this interpretation is incorrect:
Moore's avowed aim is to prove *the existence* of an external
world, not to prove *his knowledge of the existence* of an
external world. Moore himself set this out clearly in a subsequent
discussion of his lecture:



> I have sometimes distinguished between two different
> propositions, each of which has been made by some philosophers, namely
> (1) the proposition 'there are no material things' and (2)
> the proposition 'Nobody knows for certain that there are any
> material things'. And in my latest British Academy lecture called
> 'Proof of an External World' ... I implied with regard
> to the first of these propositions that it could be *proved* to
> be false in such a way as this; namely, by holding up one of your hands
> and saying '*This* hand is a material thing; therefore
> there is at least one material thing'. But with regard to the
> second of the two propositions .... I do not think I have ever
> implied that *it* could be *proved* to be false in any
> such simple way ... ('A Reply to my Critics'
> 668)




Setting aside any anti-skeptical intent therefore, what needs
assessment is the metaphysical significance of Moore's proof, as a
proof of an 'external world'. Clearly, everything here
depends on what is to count as 'external', in particular
whether Moore's demonstration of the existence of his hands proves the
existence of things that are in no way at all dependent upon experience
or thought. It is, I think, obvious that it does not; for that issue is
one which depends on broader philosophical questions about idealism
which cannot possibly be settled that way. Moore's own distinction
between questions of truth and questions of analysis should be
introduced here. Moore's 'proof' demonstrates the
'empirical' truth of a simple truism, that he has hands;
but it leaves entirely open the question of the analysis of this
truism. Yet it is at the level of analysis that the
'transcendental' question of whether things such as hands
are altogether independent of experience and thought is to be
answered.




Although, as I have indicated, Moore did not intend his
'proof' as a refutation of skepticism, he did frequently
argue against skeptical views; and in his early writings, despite the
passage quoted just now, he does sometimes give the impression that he
thinks one can refute skepticism by simply bringing forward a
straightforward case of knowledge, such as 'I know that this is a
pencil'. But on examination it turns out that his strategy here
is more subtle; he wants to argue that we get our understanding of
knowledge primarily through straightforward cases of this kind, and
thus that skeptical arguments are self-undermining: for, on the one
hand, they rely on general principles about the limits of knowledge and
thus assume some understanding of knowledge but, on the other hand,
they undermine this understanding by implying that there are no such
straightforward cases of it. The force of arguments of this kind is,
however, disputable, since the skeptic can always present his argument
as a *reductio ad absurdum* of the possibility of knowledge; and
the same point applies to Moore's other attempts to convict the skeptic
of some kind of pragmatic incoherence.




In two of his last writings, 'Four Forms of Skepticism'
and 'Certainty', Moore, perhaps dissatisfied with these
earlier arguments and with the misunderstanding of his
'proof', returned to the issue and set himself the
challenge of refuting Cartesian skepticism. Notoriously, by the end of
'Certainty' Moore acknowledges defeat: having agreed that
if he does not know that he is not dreaming, then he does not know such
things as that he is standing up and talking, he accepts (with
reservations) that he cannot know for certain that he is not dreaming.
Most commentators agree that Moore lost his way here. But it is not
clear where, since Moore makes no obvious mistake. Nonetheless the
viability of a 'common sense' response to skepticism
remains an important feature of later discussions of the topic. Moore
was clearly right when, for example, he remarked that despite Russell's
frequent skeptical professions, Russell was nonetheless perfectly sure,
without a shadow of doubt, on thousands of occasions, that he was
sitting down. But what is difficult to achieve here is a formulation of
the skeptical dialectic which both shows the importance of Moore's
'common sense' affirmations of certainty and yet avoids a
dogmatic insistence that knowledge does not need to be vindicated in
the face of skeptical argument. I myself think that Wittgenstein's
writings *On Certainty*, which were much influenced by Moore,
best indicate how this is to be achieved, but this is not the place to
demonstrate this achievement.


## 7. Moore's Legacy




Moore was not a systematic philosopher: unlike Reid's philosophy of
common sense, Moore's 'common sense' is not a system. Even
in ethics, where he comes closest to presenting a 'theory'
he explicitly disavows any aspiration to provide a systematic account
of the good. Hence, as the preceding discussions show, Moore's legacy
is primarily a collection of arguments, puzzles and challenges. One
notable addition to those mentioned already is 'Moore's
paradox': if I am mistaken about something, then I believe
something which is not the case -- perhaps that it is raining when
it is not. Yet if I attribute this mistake to myself by saying
'It's not raining but I believe that it is' my statement is
absurd. Why is this so? Why is it absurd for me to say something that
it is true about myself? Moore himself thought that the explanation
here was just that we generally believe the things we say, so that when
saying 'It's not raining' I imply that I believe this; but
Wittgenstein rightly saw that this explanation was superficial and that
Moore had put his finger on a much deeper phenomenon here which
concerns our sense of our own identity as thinkers.




This case is typical. Moore had an unparalleled ability for
identifying philosophical 'phenomena'. His own discussions
of their significance are not always satisfying; but he would be the
first to acknowledge his own fallibility. What matters is that if we
start where he starts we can be sure that we are dealing with something
that will tell us something important about ourselves and the
world.