Does self-knowledge depend upon knowledge of our own bodies?

(Another essay written when I was studying at the University of Nottingham, c. 2003.)


The self, self-knowledge, and the relationship between the self and the body, have long been issues in philosophy, especially since the publication of Descartes’ writings in the seventeenth century.

There are a number of themes involved in the question of self-knowledge and its relation to knowledge of our bodies. Principally, these are the mind-body problem (i.e. are minds and bodies distinct, and if so, how, and if not, then why does the mind seem distinct from the body), the problem of the self (i.e. what is a ‘self’ and how does it differ, if indeed it does differ, from related concepts such as ‘person’), and the problem of self-knowledge (i.e. if one has, or is, a ‘self’, what can one know about this ‘self’ as opposed to someone else’s ‘self’). Thus behind and around this one question ‘does self-knowledge depend upon our knowledge of our own bodies?’ are a host of other questions, all interconnected. Because of these interconnections, what may appear a straightforward and acceptable theory regarding one of the issues, could produce absurd consequences elsewhere within the system.

To answer the question ‘does self-knowledge depend upon our knowledge of our own bodies?’ we must have some notion of what a ‘self’ is and what constitutes knowledge of it. Questions of the self are ontological and metaphysical; those of self-knowledge are empirical, so we must be careful in our examination if we are not to commit the mistake of, as one philosopher puts it, ‘arguing directly for an epistemological conclusion from a metaphysical premiss’ (Cassam 1997, 4).

There is no consensus in modern philosophy on the issue of what, exactly, the self is. To look at all the issues involved in questions of the self would require a complete work in itself, so for now it shall be assumed that the self is not particularly problematic and adopt a fairly common sense definition of the self as being constituted by a person’s thoughts, beliefs, dispositions, intentions, etc. Note that this is specifically a definition based on mental properties and leaves aside bodily characteristics, for if we defined the self in terms of, or including, the body, then answer to the question ‘does self-knowledge depend upon knowledge of our own bodies’ would be trivially positive because self-knowledge would consist, at least partially, of knowledge of one’s body.

So far as self-knowledge is concerned, this will be taken to mean self-conscious awareness of oneself as such a thing as a self (i.e. as being a thing with thoughts, beliefs, dispositions, intentions, etc). Whether or not a person is particularly accurate in their identification of the content of their thoughts, beliefs, dispositions, intentions, and so on, is not an important issue here.


It was stated above that the modern interest in issues of self, self-knowledge and the mind-body problem is partially due to Descartes’ work. Descartes, who coined the phrase ‘cogito, ergo sum’ (‘I think, therefore I am’), was of the view that minds and bodies are two distinct substances, a theory often referred to as ‘Cartesian dualism’. The path that lead Descartes to this conclusion began with his realisation that much of what he took for knowledge was in fact ‘false opinion’, and so he decided to abandon everything he had learned and see if he could create from scratch a more accurate philosophical system. He soon discovered that he could apparently doubt everything and must have been on the point of despair when he realised that he could not doubt that he was thinking. Everything else could be an illusion, a dream, the manipulations of a dastardly demon playing tricks on his mind, but the fact that he was thinking these thoughts was beyond contradiction. This conclusion lead him to believe that the mind and the body were distinct, for how could his body and his mind be the same thing when he could doubt the existence of his body, but not his mind?

Descartes would therefore be of the opinion that self-knowledge does not depend upon knowledge of one’s body, as the cogito establishes a priori the self-knowledge that one exists.

Descartes’ philosophical system, though admirable and a great achievement in many respects, is unfortunately flawed. From his initial thinking in arriving at the cogito, he goes too far in assuming that he exists – as Lichtenberg remarks in his 18th aphorism, ‘We should say it thinks, just as we say it lightens. To say cogito is already to say too much as soon as we translate it I think’; or, in other words, Descartes is only correct in so far as he has deduced that there is some thinking going on, but from that he cannot infer the origin of this thinking. And if the cogito is invalid, and no self-knowledge is gained thereby, then the argument that the self can be known a priori promptly collapses.

There is also a grave problem with Cartesian dualism. If mind and body are distinct, one material, the other immaterial, how can they interact? Descartes states that mind and body are ‘compounded and intermingled … [to] form …a single whole’ (Descartes 1644, 159), but does not explain how this is possible.

The initial argument for mind being distinct from body – that he can doubt one but not the other – is based on a type of fallacious argument called the ‘the Masked Man Fallacy’. This fallacy begins with introducing something which is known (a person’s father, in the original of the fallacy), then presenting something seemingly unknown (a masked man), and finally revelling that the two are the same thing (the masked man is the person’s father). It could be the case that mind and body are not distinct but are merely different presentations of the same thing, and therefore Descartes is mistaken when he holds that the fact he can doubt one and not the other proves their distinctness(Descartes uses two other arguments aside from this one to demonstrate the distinctness of mind from body (‘the Argument from Clear and Distinct Understanding’ and ‘the Argument from Simplicity’), but to discuss these would leave little room for the consideration of other thinkers’ ideas. Suffice to say, neither of these other arguments are without there problems.

Hume argued against Descartes’ position. He observed that when he introspectively studies the contents of his mind, he does not ever find such a thing as a ‘self’ but only perceptions, and furthermore is never aware of a time in which his mind does not contain some perception or other. Hume concluded from this that ‘[t]he identity, which we ascribe to the mind of man, is only a fictitious one’ (Hume 1978, 259). He thought that people were ‘nothing but a bundle or collection of different perceptions, which succeed each other with an inconceivable rapidity, and are in a perpetual flux and movement’ (ibid., 252.).

Hume’s account can be taken in two ways. Either he is denying that there is such a thing as the self, or he is remarking that the self is really just the sum total of a person’s perceptions (including, in his usage, their thoughts, feelings, memories and so on). If we take the first of these two possibilities, then we must conclude that from Hume’s point of view the question ‘does self-knowledge depend upon our knowledge of our bodies?’ is nonsensical, for there is no self of which one could obtain knowledge. If we take the second as being more accurately Hume’s position, then it becomes unclear exactly what the phrase ‘self-knowledge’ means – would it refer to self-conscious awareness of one’s perceptions, or the knowledge that one’s self is just the total of one’s perceptions? As the latter case results in the surprising conclusion that only persons who know Hume’s theory of the self (or have reached it independently, or otherwise obtained the content of the theory – intriguingly, Hume’s ‘bundle’ theory seems very similar to the theory of the self given by the Buddha (or, at least, certain interpretations of the Buddha’s doctrine)) can be said to have self-knowledge, it should be treated with caution. Turning to the former, this makes the question, ‘does self-conscious awareness of our perceptions depend upon our knowledge of our own bodies?’

This does not appear to be a point specifically addressed by Hume, but by a careful reading of his thoughts it appears, perhaps unexpectedly, that he would answer ‘No’. This claim is made on the grounds that Hume states the idea of personal identity is solely due to memory (ibid., 261) and also that the contents of the mind consist of impressions, which are of two kinds, ‘sensation’ and ‘reflexion’ (ibid., 7), neither of which appear to depend upon knowledge of the body. (See also Strawson 1966, 169-70. for further support of this interpretation.)

Having extracted an answer from Hume, are we to accept it? Hume’s theory of the self contains a contradiction, which he himself pointed out (Hume 1978, 636). He argued that each of our perceptions are distinct, and also that our minds cannot perceive any connection between distinct things. Now if this were the case, it would be impossible for the mind to recognise that its perceptions form a bundle, and so would never give rise to an idea of the self. This, again, suggests we should continue searching for an adequate answer.

Both profoundly impressed and profoundly disturbed, by Hume’s philosophy, Kant attempted to refute this extreme scepticism.

On the matter of the self and its relation to the body, Kant’s theories contain elements that seem both Cartesian and Humean, and to understand this apparently contradictory synthesis, one must understand the foundations of Kant’s philosophy.

Kant distinguishes between things as they appear to us (for which he uses the term ‘phenomena’) and things as they are in themselves (for which he uses the term ‘noumena’). The noumenal world, therefore, is the ‘true’ reality (the world as it is), and the phenomena world, the world as it is represented to us by our mind (the world as it appears). It is Kant’s view that, because all our experiences are phenomenal, we cannot know the noumenal world; reality is hidden from us.

This dualism of phenomenal and noumenal (which is not a Cartesian dualism of two substances, but rather a dualism of one substance, ‘noumena’, and its representation in persons’ minds, ‘phenomena’), together with some epistemological considerations, leads to a very complex situation so far as self-knowledge is concerned. Part of the problem is that there are several distinct entities appearing in Kant’s philosophy that refer in some way to the self (see Powell 1990, 49-57).

There is a ‘self of empirical apperception’, which appears to refer simply to self-consciousness, to the awareness of one’s experiences as being experienced by oneself. In this definition of the self, both a Cartesian element and a Humean element exist, for although this self can be aware of its experiences, it can never be aware of itself (the self cannot know itself as an object of its experience, but only as the subject of its experiences) – thus, one can realise the ‘I think’ of Descartes cogito but one can not know what it is that is thinking, so the end result is a Humean bundle of experiences with no self included in the experienced bundle(Although, as Strawson (1966) notes, in Kant’s philosophy the self is at least aware of the unity of its experiences, which was a stumbling block for Hume, as pointed out earlier.). There is also the ‘noumenal self’, the self as it really is, but, as outlined above, we are only aware of phenomenal objects and not noumenal ones, so this self is utterly unknowable. Other ‘self entities’ appear in Kant’s philosophy, but they do not seem particularly relevant to the matter being investigated here, so only these two shall be considered.

This multiplicity of selfs is not the only problem with regard to the question of whether self-knowledge depends upon knowledge of our own bodies, there is also the issue of where ‘our bodies’ fit into Kant’s philosophy. Because we can only know our bodies phenomenally, it follows that our noumenal bodies are, again, utterly unknown. And if both our noumenal self and our noumenal body are unknown, there is no way of knowing whether or not the self and the body are distinct, different things, or whether in fact they are the same unknown thing. So from varying interpretations of Kant’s philosophy, the question: ‘does self-knowledge depend upon our knowledge of our own bodies?‘ will receive differing answers. However, given Kant’s insistence on the distinction between phenomena and noumena, which applies to our selves and to our bodies as much as anything else, the conclusion must be that we cannot obtain any real self-knowledge at all, and it is further possible that the question is nonsensical as, for all we know, our self and our body may be the same noumenal entity.

The modern philosopher, Quassim Cassam, has attempted to rectify the short-comings in Kant’s view of the self. He agrees with Kant that the self cannot appear in its own consciousness as an immaterial substance, but argues that the self can appear in consciousness as a material substance, which he describes as a ‘materialist conception of self-consciousness or as materialism about self-consciousness’ (Cassam 1997, 2, his italics).

Not only does Cassam argue that we are self-consciously aware of our body (something that is ‘shaped, located and solid’, as he puts it), but further that we must be so in order to be self-conscious to begin with.

Although Cassam points out that he is only concerned with self-consciousness and not with the self as such, it seems safe to assume that self-consciousness is a necessary condition for self-knowledge. Therefore, if knowledge of the body is necessary for self-consciousness, then it is thereby necessary for self-knowledge, so Cassam replies to our question ‘does self-knowledge depend upon our knowledge of our own bodies?’ with a resounding ‘Yes!’

Cassam relies on three arguments to prove his thesis, these being ‘the Objectivity Argument’, ‘the Unity Argument’ and ‘the Identity Argument’.

The Objectivity Argument states that to be aware of oneself as a subject of experience, it is a necessary condition that one is aware of oneself as a physical object in a world of physical objects. This, Cassam claims, requires both that one has the appropriate conceptual resources to consider one’s experiences as including physical objects, and also one’s experiences must be structured so that such a view of the world is permitted or warranted by them. For this to be the case, Cassam continues, one must conceive of oneself as being located appropriately to have the particular experiences that are being experienced (e.g., to have the experience of seeing or touching a tree, one must be in the vacinity of this tree), and for one to conceive this one must also conceive that one is a physical object.

So far as the first part of the argument proceeds, it seems trivial and obvious to state that to experience something in a particular way, one must be capable of this particular type of experience. It might seem that exactly the same could be said for the further claim that to conceive of one’s experiences in a certain way, one’s experiences must be structured to allow or justify such a conception, but there is an element of doubt about this after some reflection on the issue. If we consider all the different metaphysical perspectives that humankind has produced, there seem some that do not fit with this argument, for example idealism and modern scientific accounts of reality. For how could an idealist’s experiences be structured in such a way to permit or warrant the conception that material objects do not really exist, and reality is purely mental? What structuring of a scientist’s experiences could permit or warrant the conception of the world as consisting of sub-atomic particles and various forces, so that what appear to be thoroughly solid objects are actually considered to be mostly void laced with tiny bundles of energy, and the reason objects do not pass through one another is due to electromagnetic forces rather than any exclusiveness of spatial location?

To this Cassam could respond that the idealist or scientist does not experience the world in any other way then including solid physical objects, they just deny that experience is accurate on this point. The idealist or scientist does not base their view of reality on their experiences, but on reasoning (in the case of the scientist, reasoning from experimental data). But if this is the case, then it follows that the perception of reality and the conception of reality can contradict each other, which opens a gap between how we actually experience things and how we conceive our experiences. So the claim that to have an experience of physical objects it is necessary that one’s experiences permit or warrant the conception of physical objects, appears false. If this does not seem to follow, a further consideration should demonstrate the invalidity of Cassam’s standpoint. If it is necessary for one’s experiences to permit or warrant a particular conception of reality, then it should be the case that if one’s experiences do not permit or warrant a certain conception, then no such conception could be formed. In which case, it should be impossible for the idealist or scientist to obtain their conceptions of reality, for it is hard to see how any experience would permit or warrant their beliefs, which are based on reasoning rather than experience.

Moving onto the ‘self-location requirement’, Cassam argues that one must conceive of oneself as being located in a particular place to have a particular experience, and also one must conceive oneself to be a physical object amongst physical objects. Both of these claims are refuted by parapsychological reports, the first by clairvoyance (perception of distant places and events) and the second by out-of-body experiences. It must immediately be noted that it does not matter whether or not one believes in such things, it matters only that the individuals who make such reports honestly believe their own statements. Clairvoyants may believe they have somehow witnessed things that have not occurred in their immediate environments, and conceivable have no idea of the location they have observed, and therefore have no conception of their spatial relationship to objects at this distant place. And people who have had out-of-body experiences report that they drifted about and passed through solid objects without any form of resistance, leaving their physical bodies behind. Clearly, during this period they definitely do not conceive of their wandering consciousness as being located within a physical frame (though one could bring in the concept of a ‘subtle body’, which corresponds to the physical body but without having any material properties beyond extension – so it cannot interact with physical matter at all, meaning it could not be detected by any scientific instrument). Thus, whether or not such events actually occur, conceptualisation of oneself in terms other than being physical is certainly possible.

With ‘the Objectivity Argument’ despatched, there is no need to consider ‘the Unity Argument’ or ‘the Identity Argument’, for Cassam states ‘the Objectivity Argument’ forms a premise of the ‘Unity Argument’ and a conclusion of ‘the Identity Argument’ (Cassam 1997, 26). By demonstrating the falsity of an argument’s premises or conclusion we show it to be, at the very least, unsound. In effect, we have here killed three birds with one stone.

Having considered a line of philosopher from Descartes, through Hume and Kant to Cassam, and not obtained a satisfactory answer to our query, perhaps a different approach to the question would be more productive.

There is a popular thought experiment, referred to as ‘the brain in the vat experiment’ (a modernization of Descrates deceiving demon), which bears upon this issue, so an appropriate modification of this experiment may suggest a solution to the problem.

Imagine a Matrixesque scenario, where individuals are from birth placed, comatose, in vats and their brains connected to a computer that runs a simulation of a real environment – a virtual world. In this virtual world, each individual has a computer generated body that is very different from their own body; should one be, for example, a short, thin, black female, in the virtual world one’s body might be that of a tall, broad, white male. This bodily difference is the only discernible difference between the real and the virtual world, and each person has never consciously experienced their real body, only their virtual body. There seems no reason to insist that the persons in the virtual world could not be said to have self-knowledge, and if it is conceded that they have no knowledge of their real body, then self-knowledge is not dependent on knowledge of our own bodies.

There are several arguments possible against this conclusion. One could deny that the people in the virtual world can have self-knowledge, the virtual world being ontologically equivalent to a dream or hallucination, and it could be argued that self-knowledge cannot be obtained from such an illusionary existence. But, given the definitions in the introduction, if self-knowledge is taken to be self-conscious awareness of oneself as such a thing as a self (i.e. as being a thing with thoughts, beliefs, dispositions, intentions, etc), then there appears to be no reason not to grant self-knowledge to these denizens of the virtual realm. However, this point could be acknowledged and instead it could be put that the particular body one has, real or virtual, is irrelevant; that the virtual individuals perceive themselves as embodied is the crucial point, and so their self-knowledge could still be dependent on knowledge of their bodies. Even if their ‘real’ bodies are done away with entirely (so they are only ‘brains in vats’), the possession of a virtual body is just as good, and makes no difference to the matter. But this result seems paradoxical; that self-knowledge depends upon our knowledge of our bodies whether we really have bodies or not.

Leaving the thought experiment aside, perhaps an examination of one last philosopher, who has a radically different viewpoint from those already considered, may lead to a more satisfactory conclusion. Such a philosopher is Popper.

Where Descartes offered a dualism of mind and body, Popper has argued for a pluralistic reality, consisting of at least three ontologically distinct ‘worlds’. The first world (‘world 1’) is the physical world, as studied by physicists, chemists, and so on. The second world (‘world 2’) is the subjective world, consisting of psychological states, behavioural dispositions, etc. The third world (‘world 3’) is the world of objective knowledge, of the logical contents of thought. Furthermore, Popper takes an evolutionary approach to the understanding of reality, arguing that ‘world 1’ is the foundation from which ‘world 2’ has emerged with the evolution of life, and ‘world 3’ has emerged from ‘world 2’ with the evolution of human language.

In Popper’s scheme, self-knowledge of the kind under discussion here, arises in, or through interaction with, world 3. Our bodies are located in world 1, our personality is part of world 2, but our self-consciousness is ‘anchored’ in world 3 due to the logical content of our self-conscious thoughts. This model would appear to suggest that self-knowledge is far removed from our bodies, but this is not taking into account the evolutionary nature of Popper’s theory. Accordingly, Popper asserts that self-knowledge is dependent upon our knowledge of our bodies, because knowledge of our bodies is a necessary step in the development of self-knowledge.

Although generally unpopular in philosophy, Popper’s theory does seem to correspond to the findings of psychology. Psychology is, after all, just an empirical approach to the philosophical questions of self and mind, as all sciences are empirical approaches to philosophical questions. So if we are looking for some kind of empirical evidence for a particular theory of self-knowledge, psychology may be able to provide it. And in all psychological theories, from Freud’s to Piaget’s, a developing child learns first how to control its body before obtaining full self-consciousness, and experimental observations demonstrate this sequence of development (Gross 1996). The connection Popper notes between language and self-consciousness is relevant to this issue, linguistic aptitude appearing later than motor control capabilities. Of course, as Popper’s theory includes more than one world, he has to explain how the different worlds interact, but this he does in only a sketchy manner.

Another philosopher who considers an evolutionary perspective is Bergson, who argued that consciousness is shaped by evolution to understand the physical environment, ‘to think matter’ as he puts it (Bergson 1911, ix) which is why questions about the self and other such abstract entities are found to be so difficult by the human mind. Indeed, Bergson states that ‘the intellect is characterized by a natural inability to comprehend life’ (ibid., 174), and in this we can see why these issues have remained problematic throughout the history of philosophy, and why scientific approaches have been adopted to cope with them (although how successful such approaches have been is another matter).


We have examined the question of whether self-knowledge depends upon knowledge of our own bodies from the viewpoint of several different philosophers, through thought experiment, and with the findings of psychology. It would appear that self-knowledge undoubtedly does depend upon knowledge of our bodies, though perhaps not in the way meant by modern philosophers, and nor does this conclusion exclude a very different type of being; one having self-conscious awareness without any type of bodily knowledge (indeed, without any type of body, difficult though it may be to imagine such a being).

By taking a broader look at philosophical issues, instead of dealing only with the search for a priori and purely logical arguments, a greater sense of context and direction can be achieved. This does not always lead to the direct solution of philosophical problems, but can be illuminating and expand our conception of the world, which is, after all, one of the key aims of philosophy.


Allison, H. (1983). Kant’s Transcendental Idealism: An Interpretation and Defense.

Bergson, H. (1911). Creative Evolution. MacMillan & Co: London.

Cassam, Q. (1997). Self and World. Oxford University Press: Oxford.

Descartes, R. (1637). Discourse on the Method of Rightly Conducting the Reason and Seeking Truth in the Sciences in Descartes, R. (1968).

Descartes, R. (1644). Meditations on the First Philosophy in Descartes, R. (1968).

Descartes, R. (1968). Discourse on Method and the Meditations. Penguin Books: Harmondsworth.

Gross, R. (1996). Psychology: The Science of Mind and Behaviour. Hodder & Stoughton: London

Hodgson, D. (1991). The Mind Matters: Consciousness and Choice in a Quantum World. Oxford University Press: Oxford.

Hume, D. (1978). A Treatise of Human Nature. Oxford University Press: Oxford.

Lichtenberg, G.C. (1990). Aphorisms. Penguin: London. (quoted in Noordhof (2002))

Kant, I. (1781). The Critique of Pure Reason.

Noordhof, P. (2002). What is the Self? Nottingham University (unpublished course material).

Popper, K.R. (1994). Knowledge and the Body-Mind Problem: In defence of interaction. Routledge: London.

Powell, C.T. (1990). Kant’s Theory of Self-Consciousness.

Strawson, P.F. (1966). The Bounds of Sense. Methuen & Co: London.

Thompson, M. (1999). Eastern Philosophy. Hodder & Stoughton: London.

Leave a Reply

Your email address will not be published. Required fields are marked *