¹ It was already used by Bacon, initially in the form ‘conscient’ (1612), and then in the form ‘conscious’ (1625) to signify being privy to knowledge about one's faults. But the concept had no role in his philosophy.

² For the Cartesian investigations and reflections I am much indebted to Professor Hanoch Ben-Yami, with whom I spent five enjoyable days hunting together through Adam and Tannery and discussing the findings.

³ It may seem that if acts of thought are species of consciousness, then it is obvious that if one thinks one must be conscious that one thinks, just as if one sees, one necessarily perceives. But that is a mistaken analogy. If one sees a tree, then what one perceives is not that one sees it, but the tree. However, Descartes requires that the object of consciousness be the act of thinking, not the object of the act of thinking.

⁴ The latter is necessary for Locke because of the link he forged between consciousness, the concepts of a person and personal identity, and the idea of responsibility for one's actions.

⁵ ‘Thus it would be pointless trying to define, for someone totally blind, what it is to be white: in order to know what that is, all that is needed is to have one's eyes open and to see white. In the same way, in order to know what doubt and thought are, all one need do is to doubt or to think. That tells us all it is possible to know about them, and explains more about them than even the most precise definitions.’ The Search after Truth (CSM II, 417f.; AT X, 524).

⁶ ‘Such precise, naked appearances in the mind [viz. ‘abstract general ideas’], without considering how, whence or with what others they came to be there, the understanding lays up (with names commonly annexed to them) as standards to rank real existences into sorts, as they agree with these patterns, and to denominate then accordingly.’ Essay II, ix, 9.

⁷ Of course, there are other uses of this verb. For detailed discussions, see Ryle, G., On Thinking (Oxford, Blackwell, 1979)Google Scholar, White, A. R., The Philosophy of Mind (New York, Random House, 1969)Google Scholar, Rundle, B., Mind in Action (Oxford, Clarendon Press, 1997)Google Scholar, Hacker, P. M. S., Wittgenstein: Meaning and Mind (Oxford, Blackwell, 1990)Google Scholar.

⁸ One might, provocatively, say that these uses of ‘I know’ are non-epistemic, in the sense in which ‘While you were with me, I forgot all my troubles’ is not an epistemic use of ‘forget’ – it does not signify a failure of memory. So too, ‘I know that I am in pain’ or ‘I know that I intend to go’ do not signify the successful exercise of a cognitive faculty.

⁹ Synaesthesia does not exemplify such an error, for the person who suffers from synaesthesia does not claim to hear the colours of objects, but vividly to associate sounds with colours. He does not shut his eyes and hear the colours of the flowers – indeed, there is no such thing. But when he sees the colours of the flowers, he associates sounds with them.

¹⁰ Blindsight is not an exception to this conceptual truth. It is a confusion to suppose that the blindsighted see, but are not conscious of seeing. For detailed discussion, see Hyman, J., ‘Visual experience and blindsight’ in Investigating Psychology: Sciences of the Mind after Wittgenstein (London, Routledge, 1991), pp. 166–200Google Scholar.

¹¹ See The Oxford Companion to Consciousness (Oxford, Oxford University Press, 2009), p. 665Google Scholar.

¹² This thesis is sketched in Nagel's ‘Subjective and Objective’ (repr. in his Mortal Questions (Cambridge University Press, Cambridge, 1979)Google ScholarPubMed, and further developed in his book A View from Nowhere. For critical discussion of this misbegotten notion of ‘point of view’, see Bennett and Hacker, Philosophical Foundations of Neuroscience, 11.2.

¹³ See Searle, J. R., Mysteries of Consciousness (London, Granta Books, 1997), p. 201Google Scholar.

¹⁴ The notion of ‘raw feels’, subservient to a very similar muddled thought, was introduced much earlier by the behaviourist psychologist Tolman, E. C. in his Purposive Behaviour in Animals and Men (New York, Appleton-Century-Crofts, 1932)Google Scholar.

¹⁵ The term was borrowed from Lewis, C. I., Mind and the World Order (1929) (New York, Dover, 1956)Google Scholar.

¹⁶ Chalmers, D., The Nature of Consciousness (Oxford, Oxford University Press, 1996), p. ixGoogle Scholar.

¹⁷ Apparently a Google Scholar search in 2006 yielded over 600,000 books and articles with the word ‘consciousness’ in its title.

¹⁸ See Velmans, M. and Schneider, S., The Blackwell Companion to Consciousness, Introduction, p. 1Google Scholar.

¹⁹ Curiously, this muddled idea is ascribed, as a grand new insight, to contemporary members of the consciousness studies community, in particular to J. Levine. But it is at least as old as Leibniz (see note 22 below), and was beautifully stated in the nineteenth century by Huxley and Tyndall. Huxley exclaimed ‘How it is that anything so remarkable as a state of consciousness comes about as a result of irritating nervous tissue, is just as unaccountable as the appearance of Djin when Aladdin rubbed his lamp’ (Lessons in Elementary Psychology (1866), p. 210). Tyndall remarked ‘The passage from the physics of the brain to the corresponding facts of consciousness is unthinkable. Granted that a definite thought and a definite molecular action in the brain occur simultaneously, we do not possess an intellectual organ, nor apparently any rudiment of an organ, which would enable us to pass by a process of reasoning, from one to the other’ (Fragments of Science, 5^th ed. p. 420). It is striking that similar despair has been expressed in recent years by C. McGinn, who inferred, from the fact that he could not answer the question, that it is beyond the powers of the human mind to do so. For detailed critical scrutiny, see Bennett, M. R. and Hacker, P. M. S., Philosophical Foundations of Neuroscience (Oxford, Blackwell, 2003), 11.3Google Scholar.

²⁰ Of course, I am not suggesting that there are not numerous empirical problems about the various forms of consciousness. We should like to understand, not what consciousness is for, but rather what sleep is for. It is of interest to know the neural mechanisms involved in perceptual consciousness (i.e. of having one's attention caught by something in one's field of perception). It is important to discover how the brain maintains intransitive consciousness. And so on. My point is merely that the so-called ‘hard problem’ of consciousness, and the battery of related questions often cited by philosophers are merely conceptual confusions masquerading as empirical questions.

²¹ Davies, M. and Humphries, G. W., eds. Consciousness (Oxford, Blackwell, 1993), p. 9Google ScholarPubMed.

²² Leibniz nicely observed: ‘supposing that there were a machine so constructed as to think, feel and have perception, we could conceive of it as enlarged and yet preserving the same proportions, so that we might enter into it as into a mill. And this granted, we should only find on visiting it, pieces which push one against another, but never anything by which to explain a perception’ (Monadology, §17). Here is the mystery and irreducibility of consciousness. It can be updated by replacing ‘pieces that push’ with ‘neurons that fire’. The confusion remains the same.

²³ For more detailed treatment, see Hacker, P. M. S. ‘Is there anything it is like to be a bat?’ in Philosophy 77 (2002), pp. 157–74Google Scholar, and Bennett, M. R. and Hacker, P. M. S., Philosophical Foundations of Neuroscience (Oxford, Blackwell, 2003) pp. 237–351Google Scholar. Space prevents a discussion of so called subjectivity – a theme riven with incoherence. It is anatomized in Philosophical Foundations, pp. 294–302. I shall use the term ‘experience’ in the broad and ill-defined sense in which it is currently employed by students of consciousness.

²⁴ Chalmers claims that his ‘experience’ of thinking about lions has a leonine whiff about it, so ‘what it is like to think of a lion is subtly different from what it is like to think of the Eiffel tower’ (see The Conscious Mind, p. 10).

²⁵ When Kafka turned Gregor Samsa into a beetle, which was Gregor Samsa, he transgressed the bounds of sense.

²⁶ I am grateful to Hanoch Ben-Yami, Hanjo Glock, Hans Oberdiek and Herman Philipse for their comments on earlier drafts of this paper.