Summary: An Essay Concerning Human Understanding (page 2)

How does the understanding form and acquire ideas? This is the question Locke takes up in Book II.

Book II: Of Ideas

To answer it, Locke invokes the well-known metaphor of the tabula rasa. More precisely, he speaks of white paper:

Let us then suppose the Mind to be, as we say, white Paper, void of all Characters, without any Ideas; How comes it to be furnished? Whence comes it by that vast store, which the busy and boundless Fancy of Man has painted on it, with an almost endless variety? Whence has it all the materials of Reason and Knowledge? ¹

Locke's answer, which forms the cornerstone of his empiricism, is as follows:

To this I answer, in one word, From Experience: In that, all our knowledge is founded; and from that it ultimately derives it self ².

This experience encompasses both the objects of the sensible world and the inner operations of our mind.

These two kinds of experience—external and internal—provide our Understandings with all the materials of thinking, and these two are the Fountains of Knowledge, from whence all the Ideas we have, or can naturally have, do spring ³.

Our senses are first affected in various ways by external objects, giving rise to perceptions and, consequently, to ideas. In this way we acquire the ideas of white, yellow, cold, and so on—or, more generally, everything we call sensible qualities.

Sensation is therefore the primary source of our ideas.

The mind, however, does not merely receive these ideas passively. Its own operations—thinking, doubting, believing, reasoning, willing, and so on—also engage with them, giving rise to a further set of ideas that originate not from sensation but from reflection.

In both cases, an idea is a perception—whether of sensible bodies or of the operations of the mind. This is why having Ideas, and perceptions, [is] the same thing ⁴.

Here again, Locke's empiricism is on full display, reinforcing his conception of the mind as a tabula rasa.

Locke draws a distinction between two kinds of ideas: simple ideas and complex ideas.

Simple ideas are inherent to the perceived sensible object, yet human beings distinguish them readily. They recognise, for instance, that the whiteness and coldness of snow are distinct simple qualities: There is nothing can be plainer to a Man, that the clear and distinct Perception he has of those simple Ideas ⁵.

These are the Materials of all our Knowledge ⁶.

The mind can combine simple ideas to form complex ones: When the Understanding is once stored with these simple Ideas, it has the Power to repeat, compare, and unite them even to an almost infinite Variety, and so can make at Pleasure new complex Ideas ⁷.

It cannot, however, generate new simple ideas on its own.

It is important to distinguish between ideas in the mind and qualities in bodies—modifications of matter in the Bodies that cause such Perceptions in us ⁸. We should not assume, as is perhaps commonly done, that they are exactly the Images and Resemblances of something inherent in the subject ⁹.

In fact, most of those of Sensation [are] in the Mind no more the likeness of something existing without us, than the Names, that stand for them, are the likeness of our Ideas ¹⁰.

Locke defines an idea as whatsoever the Mind perceives in it self, or is the immediate object of Perception, Thought, or Understanding ¹¹, whereas a quality of an object is the Power to produce any Idea in our mind ¹².

Having established the distinction between idea and quality, Locke introduces a second: that between primary and secondary qualities.

¹ II, 1, §2, p.104
² ibid.
³ ibid.
⁴ II, 1, §9, p.108
⁵ II, 2, §1, p.119
⁶ ibid., §2, p.119
⁷ ibid.
⁸ II, 8, §7, p.134
⁹ ibid.
¹⁰ ibid.
¹¹ II, 8, §8
¹² ibid.