5 The Senses as the Basis of Knowledge: John Locke, Essay Concerning Human Understanding*
One of the striking features of Descartes’s approach to knowledge was its ‘internal’ starting point. ‘I resolved one day to pursue my studies within myself’, he wrote in the Discourse; and in the above extract from the Meditations we see him carrying out the strategy of leading the mind away from the outside world, away from the external senses, and focusing on the meditator’s inner awareness of his own existence. This very private beginning may not seem a promising start for the construction of an objective system of knowledge. But what Descartes does in the subsequent Meditations is to rely on the innate ideas with which he claims the mind is furnished. Chief of these is the idea of infinite perfection, which Descartes uses as the basis for a (controversial) proof that an infinite and perfect being, God, must really exist. And having established the existence of God, he then uses the other innate ideas, especially those of mathematics, as the foundations for his new scientific system. As he put in the Discourse, ‘I noticed certain laws which God has so ordained in nature, and of which he has implanted such notions in our minds, that after adequate reflection we cannot doubt that they are exactly observed in everything that exists or occurs in the world’.
Descartes’s appeal to innate ideas had a long ancestry (for its origins in Plato, see extract 1, above). But towards the end of the seventeenth century, in his Essay Concerning Human Understanding (1690), John Locke launched a massive broadside against the doctrine of innateness, arguing instead that the senses are the primary source of all knowledge. He compares the mind to a tabula rasa, a blank sheet or ‘white paper devoid of all characters’, and then asks ‘whence has it all the materials of reason and knowledge?’ To his own question he then supplies the famous reply, ‘in one word, from experience’. On this empiricist conception (as it has come to be known, from the Greek word empeiria, ‘experience’), observation via the senses, plus the mind’s subsequent reflection on the data so acquired, constitutes the basis of all the knowledge we have, or can have.
Locke argues that the reasoning traditionally employed to support the doctrine of innate ideas is wholly inadequate. Innatists typically appeal to ‘universal assent’ – that there are certain fundamental truths accepted by everyone; but Locke objects, first, that even if universal assent were established it would not prove innateness; and second that, in any case, these supposedly innate principles are ‘so far from having a universal assent that there are a great part of mankind to whom they are not so much as known’. He cites the cases of ‘idiots and children’. With regard to the abstract principles of logic and mathematics (often thought to be prime candidates for innately implanted principles), Locke observes that many people go through their entire lives without thinking of them at all: ‘a great part of illiterate people and savages pass many years even of their rational age, without even thinking on this and the like general propositions’. Locke then proceeds to set out his own account of how we come to knowledge of general propositions: the senses first ‘let in particular ideas’, and furnish the ‘yet empty cabinet’ (the image here is of the mind as a chamber that is entirely empty until the data from the senses enter it); the mind then gets to work on these materials, abstracting from the particular and learning the use of ‘general names’. Here and elsewhere Locke does not deny that human beings have innate capacities, but he argues that a capacity to come to know X is not at all the same as innate knowledge of X. If it were, then one would have to say, absurdly, that we have innate knowledge of everything we learn in life.1 His uncompromising conclusion is that the human mind does not have the ‘least glimmering’ of any ideas which it does not receive either from sensation or subsequent reflection.
It is an established opinion amongst some men, that there are in the understanding certain innate principles; some primary notions … characters, as it were stamped upon the mind of man, which the soul receives in its very first being; and brings into the world with it. It would be sufficient to convince unprejudiced readers of the falseness of this supposition, if I should only show … how men, barely by the use of their natural faculties, may attain to all the knowledge they have, without the help of any innate impressions; and may arrive at certainty, without any such original notions or principles. For I imagine any one will easily grant that it would be impertinent to suppose the ideas of colours [to be] innate in a creature to whom God hath given sight, and a power to receive them by the eyes from external objects; and no less unreasonable would it be to attribute several truths to the impressions of nature, and innate characters, when we may observe in ourselves faculties, fit to attain as easy and certain knowledge of them as if they were originally imprinted on the mind …
There is nothing more commonly taken for granted, than that there are certain principles both speculative and practical (for they speak of both) universally agreed upon by all mankind: which, therefore they argue, must needs be the constant impressions which the souls of men receive in their first beings, and which they bring into the world with them, as necessarily and really as they do any of their inherent faculties.
This argument, drawn from universal consent, has this misfortune in it: that if it were true in matter of fact, that there were certain truths wherein all mankind agreed, it would not prove them innate, if there can be any other way shown how men may come to that universal agreement in the things they do consent in; which I presume may be done.
But, which is worse, this argument of universal consent, which is made use of to prove innate principles, seems to me a demonstration that there are none such: because there are none to which all mankind give a universal assent. I shall begin with the speculative, and instance … Whatsoever is, is; and It is impossible for the same thing to be, and not to be, which of all others I think have the most allowed title to innate … But yet I take liberty to say that these propositions are so far from having a universal assent that there are a great part of mankind to whom they are not so much as known.
For, first it is evident that all children, and idiots, have not the least apprehension or thought of them: and the want of that is enough to destroy that universal assent, which must needs be the necessary concomitant of all innate truths: it seeming to me near a contradiction to say that there are truths imprinted on the soul which it perceives or understands not; imprinting, if it signify any thing, being nothing else but the making certain truths to be perceived. For to imprint any thing on the mind without the mind’s perceiving it seems to me hardly intelligible. If therefore children and idiots have souls, have minds, with those impressions upon them, they must unavoidably perceive them, and necessarily know and assent to these truths – which since they do not, it is evident that there are no such impressions. For if they are not notions naturally imprinted, how can they be innate? And if they are notions imprinted, how can they be unknown?
To say a notion is imprinted on the mind, and yet at the same time to say that the mind is ignorant of it, and never yet took notice of it, is to make this impression nothing. No proposition can be said to be in the mind which it never yet knew, which it was never yet conscious of. For if any one may, then, by the same reason, all propositions that are true, and the mind is capable ever of assenting to, may be said to be in the mind, and to be imprinted: since if any one can be said to be in the mind which it never yet knew, it must be only because it is capable of knowing it – and so the mind is, of all truths it ever shall know. Nay, thus truths may be imprinted on the mind, which it never did, nor ever shall know: for a man may live long, and die at last in ignorance of many truths, which his mind was capable of knowing, and that with certainty. So that if the capacity of knowing be the natural impression contended for, all the truths a man ever comes to know will, by this account, be, every one of them, innate; and this great point will amount to no more, but only to a very improper way of speaking; which whilst it pretends to assert the contrary, says nothing different from those who deny innate principles. For nobody, I think, ever denied that the mind was capable of knowing several truths.
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