Empiricism is the philosophical stance according to which the senses are the ultimate source of human knowledge. It rivals rationalism according to which reason is the ultimate source of knowledge. In a form or another, empiricism is a chapter of most philosophical tradition. In Western philosophy, empiricism boasts a long and distinguished list of followers in all ages; probably the most fertile moment for this trend happened during the early modernity, with the so-called British empiricists, whose rank includes authors of the caliber of John Locke and David Hume.
The Centrality of Experience
Empiricists claim that all ideas that a mind can entertain have been formed through some experiences or – to use a slightly more technical term – through some impressions; here is how David Hume expressed this creed: "it must be some one impression that gives rise to every real idea" (A Treatise of Human Nature, Book I, Section IV, Ch. vi). Indeed – Hume continues in Book II – "all our ideas or more feeble perceptions are copies of our impressions or more lively ones". Under this characterization, empiricism is the claim that all human ideas are less detailed copies of some experience or other.
Empiricists seem to have several cases on their side, cases where a person’s lack of experience precludes her from possessing an adequate idea. Consider pineapples, a favorite example among early modern writers. How can you explain the flavor of a pineapple to someone who has never seen one such fruit? Here is what John Locke says about pineapples in his Essay:
"If you doubt this, see whether you can by words give anyone who has never tasted pineapple an idea of the taste of that fruit. He may approach a grasp of it by being told of its resemblance to other tastes of which he already has the ideas in his memory, imprinted there by things he has taken into his mouth; but this isn’t giving him that idea by a definition, but merely raising up in him other simple ideas that will still be very different from the true taste of pineapple." (An Essay Concerning Human Understanding, Book III, Chapter IV)
There are of course countless cases analogous to the one cited by Locke. They are typically exemplified by claims such as: "You can’t understand what it feels like …" Thus, if you never gave birth, you don’t know what it feels like; if you never dined at the famous Spanish restaurant El Bulli, you don’t know what it was like; and so on.
Questions for Empiricists
Empiricism is not free from possible objections, however. One of them concerns the process of abstraction through which ideas are supposed to be formed from impressions. For instance, consider the idea of a triangle. Presumably, an average person will have seen plenty of triangles, of all sorts of types, sizes, colors, materials … Which of those experiences contributed to the idea of the triangle? To put it simply: what is the size and color of the idea of triangle? Or, consider the idea of love: is it specific to positional qualities such as gender, sex, age, upbringing, or social status, or is there really one abstract idea of love?
Empiricists will typically reply that the process of abstraction embeds a loss of information: impressions are vivid, while ideas are fainted memories of reflections. If we were to consider each impression on its own, we would see that no two of them are alike; but, when we remember, different impressions – of, say, two different triangles – those will appear as falling under the same idea – viz. the idea of a triangle.
Specific ideas, then, may pose hard problems for empiricists. One such is the idea of the self: which sort of impression could ever teach us such an idea? For Descartes, indeed, the self is an innate idea, one that is found within a person independently of any specific experience: rather, the very possibility of having an impression depends on a subject’s possessing an idea of the self; analogously, Kant centered his philosophy on the idea of the self, which is a priori according to the terminology he introduced. So, what is the empiricist account of the self?
Probably the most fascinating and effective reply comes, once again, from Hume. Here is what he wrote about the self in the Treatise (Book I, Section IV, Ch. vi):
"For my part, when I enter most intimately into what I call myself, I always stumble on some particular perception or other, of heat or cold, light or shade, love or hatred, pain or pleasure. I never can catch myself at any time without a perception, and never can observe any thing but the perception. When my perceptions are removed for any time, as by sound sleep, so long am I insensible of myself, and may truly be said not to exist. And were all my perceptions removed by death, and could I neither think, nor feel, nor see, nor love, nor hate, after the dissolution of my body, I should be entirely annihilated, nor do I conceive what is further requisite to make me a perfect nonentity. If any one, upon serious and unprejudiced reflection, thinks he has a different notion of himself, I must confess I can reason no longer with him. All I can allow him is, that he may be in the right as well as I, and that we are essentially different in this particular. He may, perhaps, perceive something simple and continued, which he calls himself; though I am certain there is no such principle in me. "
Whether Hume was right or not is beyond the point. What matters is that the empiricist account of the self is, typically, one that tries to do away with the unity of the self: that there is one thing that survives throughout our whole life is an illusion.
Further Online Readings and Sources
"Rationalism vs. Empiricism" at the Stanford Encyclopedia of Philosophy.