Summary: An Essay Concerning Human Understanding

The understanding, which is what gives man his superiority over animals, is comparable to the eye: it makes us see things, but it does not naturally see itself.
Let us try to reverse our view and make the understanding itself the object of our examination. Perhaps this will enable us to set down any Measure of the Certainty of our Knowledge ¹.

Locke will not, in order to do this, examine the nature of the brain from a physicalist or materialist approach. The aim here is to identify the various faculties of our mind, and the way in which our ideas are formed.
Thus, we may discover the limits of knowledge, and as a result, we may identify an area of thought where truth is attainable, and another where it is impossible.
This, for Locke, is the best way to combat scepticism, which doubts the possibility of attaining any truth whatsoever: it is a matter of being finer than this radical doubt, and identifying the kind of idea that this doubt legitimately concerns, and the kind of idea that resists it.

Locke specifies what he means by idea in the general sense: whatsoever is the Object of the Understanding when a Man thinks ².

Book I: Innate notions

In the first book, Locke attacks the doctrine of innate ideas, found in Descartes. This doctrine asserts that man is born with certain ideas already formed in the mind, such as that of God, as he argues in his Meditations on First Philosophy.

Locke shows that man can discover all ideas by the simple use of his natural faculties. Thus man is not born with the idea of red in him, but acquires it through sight.

However, certain principles are universally recognised. Can we not imagine that they are so by virtue of their innate character?

Locke questions the existence of universal principles. Even a tautology of the type "what is is" is ignored by a large part of humanity, for example children.

Counter-argument: it is innate in their souls but their souls do not see it; they do not realise it.

Locke shows that to say that an idea is innate means that the soul naturally perceives that idea: that is the meaning of this doctrine. So there can be no innate idea unnoticed.

Finally, the only thing Locke concedes to innateness is the fact that the faculty of understanding is innate.

Chronologically, these are the processes by which ideas are formed in our minds:

- the senses introduce us to the world, and as a result ideas appear in our minds

- these, becoming increasingly familiar, enter our memory and we give them names

- the mind abstracts other ideas from these ideas brought by the senses: these are the general concepts

- the mind reasons about these concepts and discovers others.

Locke devotes an entire chapter of An Essay Concerning Human Understanding to practical principles, to show that none of them are universal and therefore innate. Indeed, if morality were innate, we would all be moral, and we would all have remorse of conscience in the event of murder or theft, which is not the case. Rules of morality need to be proved, so they are not innate.

Locke takes up a classic argument among sceptics, which shows the diversity of morals among peoples: the child sacrifices practised by the Greeks or Romans, the abandonment of the elderly in certain tribes, etc.

In fact, we take practical principles to be innate because we have not seen or have forgotten their origin. If we examine carefully, Doctrines, that have been derived from no better original, than the Superstition of a Nurse, or the Authority of an old Woman; may, by length of time, and consent of Neighbours, grow up to the dignity of Principles in Religion or Morality ³.

¹ An Essay concerning Human Understanding, Clarendon Oxford University Press, Oxford, 1975, I, 1, §2, p.44
² §8, p.47
³ Book I, 3, §22, p.81