John Locke‟s Empiricism A Theory of Knowledge in Contrast to Descartes‟ Rationalism and Foundationalism John Locke • John Locke (1632-1704) also lived during the Scientific Revolution. • However, Locke was not an impressed with the geometric method as a model for knowledge as Descartes was. • Rather, Locke was influenced by the experimental method of the „new‟ sciences as used by thinkers like Robert Boyle and Isaac Newton. Ideas • Locke does not mean quite the same thing we do when he speaks of „ideas‟: • “Whatsoever the mind perceive in itself or is the immediate object of perception, thought, or understanding, that I call „idea‟.” • Sometimes we will use „idea‟, „sensation‟, „perception‟, and „sense perception‟ interchangeably; although Locke also includes the content of thoughts as „ideas‟. Innate Ideas • Unlike Descartes, Locke argues that we do not have any innate ideas. At birth, our minds are like “white paper, void of all character without any ideas.” • This applies both to what he calls “speculative” principles (those pertaining to the nature of reality) and “practical” principles (moral truths). • Locke‟s argument against innate ideas begins by considering the innateness of necessary truths like the Law of Non-Contradiction. Innate Ideas • The Law of Non-Contradiction says that the same statement cannot be both true and false. • This is just the kind of principle that Descartes took to be self-evident and known through intuition. • But Locke wants to know what evidence there is that the Law of Non-Contradiction is innate. Innate Ideas • He considers three possibilities: • First, the fact that they are universally agreed to is evidence that they are innate. • Second, their innateness implies that they are understood to be true by children. • Third, the fact that they are known only through reason is evidence of their innateness. Innate Ideas • Locke denies that principles like the Law of Non- Contradiction are universally agreed to. • But even if they were universally agreed to, that wouldn‟t make them innate. • That‟s because we can all agree that some principles are true even though those principles are only known through experience (like the principle that the earth revolves around the sun). Innate Ideas • Second, Locke argues, if these principles were innate, then they‟d be understood to be true by children; but Locke says this obviously isn‟t the case. • Finally, the fact that such principles are known only through reason does not show that they are innate. Innate Ideas • For one thing, if everything known through reason alone were innate, then all mathematical truths would be innate because they are all known through reason. • But even rationalists would agree that not all mathematical truths are innate (if they were, then subjects like calculus and differential equations - and even yet-to-be-discovered subjects - would all be innately known). The Origin of Ideas • So, Locke dismisses the claim that we are born with some ideas. • He replaces this claim with another: that all of our ideas originate in experience. • But Locke thinks there are different kinds of ideas, and that they have different sources. • While Locke‟s complete taxonomy of ideas is very complex, we can discuss two of his most important distinctions. Sensation and Reflection • According to Locke, our ideas come from experience in two ways. • First, ideas enter the mind through our senses. Locke calls this sensation. • Second, our we have experiences of our minds‟ own operations (like thinking, willing, believing, and desiring). Locke calls this reflection. • All of our ideas ultimately come from sensation and reflection - including knowledge of our own minds. Simple and Complex Ideas • Locke also distinguishes between simple and complex ideas. • A simple idea is “uncompounded, contains nothing but one uniform appearance or conception in the mind, which is not distinguishable into different ones.” • A complex idea is composed of simple ideas. • The idea RED is a simple idea, whereas „red shoe‟ is a complex idea. Abstract Ideas • The simple ideas received from sensation are always particulars: We perceive this particular shape or that particular color. • We also have a capacity that Locke calls abstraction (recall Aquinas). • This is the mental ability to convert particular simple ideas into universal or general ideas - an idea of a triangle in general or of tables in general. Ideas and Qualities • The challenge for Locke is to explain how our ideas (which are only in our minds) give us knowledge of objects that exist beyond them - ordinary physical objects such as tables and chairs - as well as scientific knowledge. • He explains this by arguing that our ideas represent real qualities of things. Qualities • For Locke, a Quality is a property of an external object. • A Primary Quality is an intrinsic property of any material object, whether or not it is perceived. These qualities are “utterly inseparable from the body in what sate soever it may be.” • A Secondary Quality is the power of objects to produce certain ideas in our minds “by the operation of insensible particles on our senses.” Qualities • Examples of primary qualities are shape, extension, solidity, motion and number. • Examples of secondary qualities are colors, sounds, tastes, smells, and textures. • Secondary qualities are not in the objects themselves but are merely “the power to produce various sensations in us by their primary qualities.” Representation & Resemblance • According to Locke, ideas represent qualities by resembling them. • The ideas of primary qualities resemble the qualities themselves, but the ideas of secondary qualities resemble nothing in objects themselves. • Our ideas of colors and sounds do not resemble the secondary qualities, nor do they resemble the primary qualities that are the ground of these secondary qualities. Knowing the External World • But if our ideas of colors, tastes, sounds, odors and textures do not resemble the real qualities of external objects, how can the former give us knowledge of the latter? • Locke gives at least four arguments for the claim that our sensory experiences provide us with evidence for the existence of external objects and their characteristics. Knowing the External World Locke‟s first argument is the following: “First, because we cannot have ideas of sensation but by the inlet of the senses. It is plain those perceptions are produced in us by exterior causes affecting our senses: because those that want the organs of any sense, never can have the ideas belonging to that sense produced in their minds. This is too evident to be doubted: and therefore we cannot but be assured that they come in by the organs of that sense, and no other way. The organs themselves, it is plain, do not produce them: for then the eyes of a man in the dark would produce colours, and his nose smell roses in the winter: but we see nobody gets the relish of a pineapple, till he goes to the Indies, where it is, and tastes it.” (E IV.xi.4) • Locke‟s argument here can be reconstructed as follows: 1. If visual experiences were caused by the eyes (or, presumably, by the mind) of the person having them, then blind people would have visual experiences. 2. Blind people do not have visual experiences. 3. Therefore, visual experiences are not caused by the eyes (or the mind) of the person having them. • Locke intends similar arguments to apply to all other sensory modalities. Knowing the External World • Locke‟s second argument is as follows: “Secondly, Because we find that an idea from actual sensation, and another from memory, are very distinct perceptions. Because sometimes I find that I cannot avoid the having those ideas produced in my mind. For though, when my eyes are shut, or windows fast, I can at pleasure recall to my mind the ideas of light, or the sun, which former sensations had lodged in my memory; so I can at pleasure lay by that idea, and take into my view that of the smell of a rose, or taste of sugar. But, if I turn my eyes at noon towards the sun, I cannot avoid the ideas which the light or sun then produces in me. So that there is a manifest difference between the ideas laid up in my memory, (over which, if they were there only, I should have constantly the same power to dispose of them, and lay them by at pleasure,) and those which force themselves upon me, and I cannot avoid having. And therefore it must needs be some exterior cause, and the brisk acting of some objects without me, whose efficacy I cannot resist, that produces those ideas in my mind, whether I will or no.” (E IV.xi.5) Locke‟s argument here may be reconstructed as follows: 1. If I have a visual experience, then it must have a cause. 2. If I caused my visual experience, then I can control which visual experiences I have. 3. I cannot always control which visual experiences I have. 4. Therefore, I do not cause all of my visual experiences. 5. Therefore, some of my visual experiences must have an external cause. Knowing the External World • Locke‟s third argument is as follows: “Thirdly, because pleasure or pain, which accompanies actual sensation, accompanies not the returning of those ideas without the external objects. Add to this, that many of those ideas are produced in us with pain, which afterwards we remember without the least offence. Thus, the pain of heat or cold, when the idea of it is revived in our minds, gives us no disturbance; which, when felt, was very troublesome; and is again, when actually repeated: which is occasioned by the disorder the external object causes in our bodies when applied to them: and we remember the pains of hunger, thirst, or the headache, without any pain at all; which would either never disturb us, or else constantly do it, as often as we thought of it, were there nothing more but ideas floating in our minds, and appearances entertaining our fancies, without the real existence of things affecting us from abroad.” (E IV.xi.6) This argument can be reconstructed as follows: 1. If there is a difference between having a headache and remembering a headache, then they must have different causes. 2. There is a difference between having a headache (which is painful) and remembering a headache (which is not painful) 3. Therefore, they have different causes (an external cause when having it, my mind when remembering it). Knowing the External World • The fourth and last argument Locke gives is as follows: “Fourthly, because our senses assist one another's testimony of the existence of outward things, and enable us to predict. Our senses in many cases bear witness to the truth of each other's report, concerning the existence of sensible things without us. He that sees a fire, may, if he doubt whether it be anything more than a bare fancy, feel it too; and be convinced, by putting his hand in it. Which certainly could never be put into such exquisite pain by a bare idea or phantom, unless that the pain be a fancy too: which yet he cannot, when the burn is well, by raising the idea of it, bring upon himself again.” (E IV.xi.7) This last argument may be reconstructed as follows: 1. Repeated observation has shown me that ideas of different senses that I experience as closely correlated likely have the same cause (and since I know that I didn‟t cause them, they have an external cause). 2. Therefore, the closely correlated ideas of different senses that I currently experience likely have the same external cause.