Essential Thinkers #23 John Locke, the Empiricist, on the Nature of Human Understanding

In his day, John Locke (1632-1704) was an important political figure and author of the liberal exposition Two Treatises of Government. An associate of the Earl of Shaftesbury, Locke spent time in exile in Holland, returning to England after the ‘Glorious Revolution’ of 1688. It is for his views on the nature of human knowledge, however, in his Essay Concerning Human Understanding that he is remembered in modern philosophy. 20 years in the writing, the book was to exert such an influence on the next 100 years of Western though that its author is considered by many to be the greatest British philosopher of all time. The works of George Berkeley, Immanuel Kant, and David Hume are all direct successors of Locke’s Essay.

The subject of Locke’s Essay, as given in the title, is the nature of human understanding, that is, the very way in which the human mind collects, organises, classifies and ultimately makes judgements based on data received through the senses. Greatly influenced by the scientific turn of his day, and a personal friend of two renowned contemporary scientists, Robert Boyle and Isaac Newton, Locke’s intent was to set the foundations of human knowledge on a sound scientific footing. He had read with great interest Rene Descartes’ Meditations on First Philosophy, but rejected the rationalist philosophy that underpinned its conclusions.

For Locke, there could be no innate knowledge: rather, everything we know must be derived from experience, through the actions of the physical world on our sense organs. This is the view now known as empiricism, a view still central, in essence if not detail, to the philosophies of W.V.O. Quine and other modern thinkers. Locke’s detractors, the Rationalists (Rene Descartes, George Berkeley, Gottfried von Leibniz) with whom the Empiricists battled for ideological supremacy throughout the 17^th and 18^th centuries, have their modern counterparts in the supporters of Noam Chomsky and his philosophy of innate, or generative, grammar.

Locke states that the mind at birth is like a blank slate, or tabula rasa, waiting to be written on by the world of experience. All human knowledge is derived from ideas presented to the mind by the world of experience. However, these ideas can be classified into two general sorts. There are complex ideas and simple ideas. Simple ideas are the immediate products of sensory stimulation, examples would be ‘yellow,’ ‘bitter,’ ‘round,’ ‘hard,’ and so on. Complex ideas are constrictions out of simple ideas, and are the product of internal mental operations. These include all our ideas of familiar material objects, such as tables, chairs, cats, dogs and horses. But complex ideas need not represent anything real in the world. This accounts for ideas like that of a unicorn, a complex idea itself made up of other complex ideas, such as ‘horse’ and ‘horn.’

Among Locke’s simple ideas is a distinction between those that are primary qualities of objects and others that are secondary qualities. The distinction divides those qualities thought to be essential and inherent to all objects and those that are apparent only on account of the effect objects have on our sense. Primary qualities are those such as solidity, extension, shape, motion or rest, and number. Secondary qualities are those such as colour, scent and taste. These are secondary because, according to Locke, they do not inhere in objects themselves, but are causally produced only in our minds by the effect of an object’s primary qualities upon our senses. Another way of conceiving them is to say primary qualities are objective (really exist) and secondary ones subjective (only exist in the minds of observers).

In the popular conundrum of whether a falling tree makes a sound when there is no one to hear it, Locke’s view would be that the falling tree creates vibrations in the air, but that there is no ‘sound’ strictly speaking, since sound is not a ‘real’ or primary quality. This view, sometimes called ‘scientific essentialism,’ leads to the metaphysical conclusion, plausible to many modern thinkers, that without a perceiving mind, there is no such thing in the world as colour or sound, sweet or sour and so on; but there are really such things as shape, extension and solidity, independently of whether anyone perceives them or not.

[Summarized from Philosophy 100 Essential Thinkers by Philip Stokes, 2012.]

Lord, Give Us Today Our Daily Idea(s)