John Locke and George Berkeley
As an advocate of modern empiricism, John Locke stands against this idea. Empiricism is the belief that ALL knowledge comes from sense experience and Locke was the first to offer a systematic response to rationalism after Descartes. To get this project off the ground, he had to first demonstrate the flaw in the theory of innate ideas; a very popular idea in the 18th century due in large part to the influence of Descartes.
To begin let's consider the evidence in favor of innate ideas. If an idea is going to be innate it seems that it has to be universally held and it has to be something that doesn't have to be taught. But suppose an idea exists that has the traits. Does that mean it’s innate? No. As Locke puts it universal consent does not prove innateness. Even if an idea, like the law of identity, let's say, were universally held that would not be enough to prove innateness if there were some other, better, explanation. So while universal consent is a necessary condition for innateness, it’s not sufficient.
But it gets worse for innate ideas. According to Locke, there aren't even any ideas that are universally held. What about the law of Identity? You could easily find people, children perhaps, who knew nothing of this idea. But if an idea is innate everyone would know it. Rationalists might respond by saying that while the idea is innate it takes sense experience to trigger it. But, Locke asks, how is this any different from the claim that sense experience is where the idea is learned? The only conclusion that makes sense is that the mind at birth is a blank tablet (or tabula rasa like Aristotle said). All our knowledge comes from sense experience.
In fact, according to Locke's theory which he believed was the common-sense alternative to rationalism, there are two sources for all our knowledge: sensation and reflection. The sensation is a passive faculty of the mind (sort of like Descartes' passive faculty of perception) where we take in simple ideas through the five senses. These simple ideas, like sound, color, shape, smell, texture, are then combined in the mind by the active faculty of reflection. The results of this reflection are complex ideas.
For example, when you look at an object, a tree let's say, you are directly observing through the faculty of sensation, simple ideas. You see the tree's shape and color. You can feel the texture of the tree. You can sense a smell (and taste if you care to). All of these are simple ideas. They enter through the separate senses and must be combined in the mind. This combination results in the perception you have of the tree; which is a complex idea. This complex idea represents the actual object and this view is called "representative realism." The main point to remember about this theory is that the only things you ever directly perceive are ideas; simple and complex. As we'll see in a moment this leads to a serious problem for Locke's metaphysics as well as his epistemology.
First, however, we should consider in more detail Locke's thoughts on the objects themselves. We perceive them through the medium of ideas but what are the objects themselves composed of? There are two components to all objects: qualities and substance. Qualities are the attributes the object has and are what we perceive as simple ideas. There are two types of qualities: primary and secondary. Primary qualities, things like shape, motion, number, are qualities that are actually in the object itself. Consider, as Locke does, a snowball. It has a certain shape which is part of the object just as the fact of it being in motion (or not) is also in the object. On the other hand, color is not really in the object. An object's color is simply its ability to reflect our eyes certain parts of the light wave and those parts are the color we see. Because color is not in the object Locke terms it is a secondary quality. He defines these as not being in the object except as a power in the object to cause in us a certain sensation. In addition to color, smell and taste would be examples of secondary qualities.
Qualities are what we perceive of the object. But, it’s obvious to Locke that the object must be more than that. After all, qualities cannot just be floating in space! The shape has to be in something just as texture, motion, or any other quality. So there must be more to the object than its qualities. There must be the "stuff" that the qualities are in; something that "stands under the qualities so to speak. This something Locke termed substance; which simply means "stands under." The funny thing about substance is that it cannot be perceived. After all, it’s not a quality it’s what the qualities are in. So Locke defines substance as "something we know not of." We can't have direct knowledge of it because we can't have direct perceptions of it. Remember knowledge comes from sense experience so our knowledge of substance must be indirect. For Locke, it’s a matter of common sense. Qualities have to be in something so even though we can't see something, it must be there. This represents another potential problem for Locke's theory.
Speaking of representing let's get back to representative realism and see what problems this leads to. The problems are likely to be more serious now that we have an unobservable substance to deal with. Locke claims that the ideas we get from an object represent it. So the complex ideas I have of a tree look like a tree. Question: Is there any way for me to verify this claim? It would seem not. Remember, the only things we directly perceive are ideas. So I cannot perceive the object itself except through my ideas. So I can't tell whether my idea represents the object since I can't perceive the object! Not only that, Locke's theory depends on the existence of a material substance that cannot, even in principle, be perceived. For an empiricist, he sure is appealing to a lot of unobservable entities.
That's exactly what another empiricist named George Berkeley began to think. If empiricism is the claim that all knowledge comes from sense experience, then Locke has gone far beyond the boundary marked out by that definition. Let's see if we can't figure a way out of this problem by using a simple example. Suppose I said that there was a palm tree in the room you're in. Do you believe me? Likely as not you're saying no. Why? Because you can't perceive it. But suppose I say that this is an unobservable palm tree. That is, it exists, you just can't perceive it. Now, do you believe me? Probably not because you recognize (as Berkeley does) that existence and perception are connected. For something to exist it must be perceived. If something cannot be perceived, it simply doesn't exist. This is what Berkeley meant when he said "Esse est percipi:" to be is to be perceived.
To say that substance exists but cannot be perceived is just nonsense. If something exists then it has to be perceived. So, since substance cannot be perceived, it doesn't exist. This of course is a radical idea and much different than the dualism of Descartes and Locke. In this respect, Locke was like Descartes. They both believed in two substances: a mental substance and a physical substance. But, we've just shown that physical substance can't be perceived. And, only things that can be perceived exist. So we have to conclude that physical substance doesn't exist. That means everything that exists is the product of mental substance. In other words, everything is just a collection of ideas. This metaphysical position, which Berkeley was championing, is called idealism.
Notice that this theory not only deals with the problem of substance (by denying its existence) it also solves the problem of representative realism. We no longer have to suppose that ideas represent objects; ideas are objects. The objects we see are nothing but a collection of ideas.
While this position does overcome the problems of representative realism, it may seem to have a few of its own (like denying the existence of material substance!). The serious problem seems to be what idealism implies. If existence is tied to perception then what happens when nobody perceives an object? Does it just disappear? For example, right now I don’t perceive my car and if no one else is either then it seems that it doesn't exist. This is very much like the old question "If a tree falls in the forest and no one is there to hear it, does it make a sound?" So, do objects pop in and out of existence? Well, theoretically yes, unless there is some mind constantly perceiving them. Before we address this we should probably investigate one of the motivations for Berkeley's idealism.
Let's consider the alternatives. We've seen dualism and the problems it entails. While it’s tempting to dismiss them out of hand it seems that dualism is inherently problematic and unworkable. The other option is materialism. Granted, it solves the problem of interaction but considers some of its broader effects. Despite Hobbes' claim that materialism leaves room for God most materialists to recognize that, taken to its logical conclusion, this theory eliminates the need for God and His existence. This implication was unacceptable to Berkeley. There has to be a way to avoid the problems of dualism and the atheism of materialism. Thus, we arrive at the theory of idealism. So what do we do about the problem of existence? What we need is a universal perceiver who is always assuring the continued existence of objects even when we don’t perceive them.
The solution Bishop Berkeley (did I mention he was a Bishop?) was to offer to all these problems was ingenious. According to Berkeley, we can infer the continued existence of objects from observation. For example, if I light a candle and then leave the room, when I come back later it’s burned down. So it seems that it has been in existence even though we haven't perceived it. But for this to be true someone must be observing it; a universal perceiver. By now, of course, you've guessed that this universal perceiver is God. Quite simply this seems to be the only explanation that consistently works and solves the problems. To be an empiricist in epistemology implies that you must be an idealist in metaphysics. So what is the answer to the tree falling question? Yes, it makes a sound because God perceives it!
Interestingly enough one of the founders of quantum physics recognized that appearance and reality really may be connected. Werner Heisenberg realized that from a quantum standpoint, things don't exist unless we observe them. This seems to be implied by Heisenberg's uncertainty principle. When we observe subatomic phenomena we change what happens to them. There's no way for us to tell what subatomic particles are doing when we're not observing them. For all we know they may be doing nothing at all; they may not exist. By observing the particles we may bring them into existence. Needless to say, Heisenberg was a big fan of Berkeley! But as we'll see next, things are about to get much worse for empiricism and where it takes us. Stay tuned.
To begin let's consider the evidence in favor of innate ideas. If an idea is going to be innate it seems that it has to be universally held and it has to be something that doesn't have to be taught. But suppose an idea exists that has the traits. Does that mean it’s innate? No. As Locke puts it universal consent does not prove innateness. Even if an idea, like the law of identity, let's say, were universally held that would not be enough to prove innateness if there were some other, better, explanation. So while universal consent is a necessary condition for innateness, it’s not sufficient.
But it gets worse for innate ideas. According to Locke, there aren't even any ideas that are universally held. What about the law of Identity? You could easily find people, children perhaps, who knew nothing of this idea. But if an idea is innate everyone would know it. Rationalists might respond by saying that while the idea is innate it takes sense experience to trigger it. But, Locke asks, how is this any different from the claim that sense experience is where the idea is learned? The only conclusion that makes sense is that the mind at birth is a blank tablet (or tabula rasa like Aristotle said). All our knowledge comes from sense experience.
In fact, according to Locke's theory which he believed was the common-sense alternative to rationalism, there are two sources for all our knowledge: sensation and reflection. The sensation is a passive faculty of the mind (sort of like Descartes' passive faculty of perception) where we take in simple ideas through the five senses. These simple ideas, like sound, color, shape, smell, texture, are then combined in the mind by the active faculty of reflection. The results of this reflection are complex ideas.
For example, when you look at an object, a tree let's say, you are directly observing through the faculty of sensation, simple ideas. You see the tree's shape and color. You can feel the texture of the tree. You can sense a smell (and taste if you care to). All of these are simple ideas. They enter through the separate senses and must be combined in the mind. This combination results in the perception you have of the tree; which is a complex idea. This complex idea represents the actual object and this view is called "representative realism." The main point to remember about this theory is that the only things you ever directly perceive are ideas; simple and complex. As we'll see in a moment this leads to a serious problem for Locke's metaphysics as well as his epistemology.
First, however, we should consider in more detail Locke's thoughts on the objects themselves. We perceive them through the medium of ideas but what are the objects themselves composed of? There are two components to all objects: qualities and substance. Qualities are the attributes the object has and are what we perceive as simple ideas. There are two types of qualities: primary and secondary. Primary qualities, things like shape, motion, number, are qualities that are actually in the object itself. Consider, as Locke does, a snowball. It has a certain shape which is part of the object just as the fact of it being in motion (or not) is also in the object. On the other hand, color is not really in the object. An object's color is simply its ability to reflect our eyes certain parts of the light wave and those parts are the color we see. Because color is not in the object Locke terms it is a secondary quality. He defines these as not being in the object except as a power in the object to cause in us a certain sensation. In addition to color, smell and taste would be examples of secondary qualities.
Qualities are what we perceive of the object. But, it’s obvious to Locke that the object must be more than that. After all, qualities cannot just be floating in space! The shape has to be in something just as texture, motion, or any other quality. So there must be more to the object than its qualities. There must be the "stuff" that the qualities are in; something that "stands under the qualities so to speak. This something Locke termed substance; which simply means "stands under." The funny thing about substance is that it cannot be perceived. After all, it’s not a quality it’s what the qualities are in. So Locke defines substance as "something we know not of." We can't have direct knowledge of it because we can't have direct perceptions of it. Remember knowledge comes from sense experience so our knowledge of substance must be indirect. For Locke, it’s a matter of common sense. Qualities have to be in something so even though we can't see something, it must be there. This represents another potential problem for Locke's theory.
Speaking of representing let's get back to representative realism and see what problems this leads to. The problems are likely to be more serious now that we have an unobservable substance to deal with. Locke claims that the ideas we get from an object represent it. So the complex ideas I have of a tree look like a tree. Question: Is there any way for me to verify this claim? It would seem not. Remember, the only things we directly perceive are ideas. So I cannot perceive the object itself except through my ideas. So I can't tell whether my idea represents the object since I can't perceive the object! Not only that, Locke's theory depends on the existence of a material substance that cannot, even in principle, be perceived. For an empiricist, he sure is appealing to a lot of unobservable entities.
That's exactly what another empiricist named George Berkeley began to think. If empiricism is the claim that all knowledge comes from sense experience, then Locke has gone far beyond the boundary marked out by that definition. Let's see if we can't figure a way out of this problem by using a simple example. Suppose I said that there was a palm tree in the room you're in. Do you believe me? Likely as not you're saying no. Why? Because you can't perceive it. But suppose I say that this is an unobservable palm tree. That is, it exists, you just can't perceive it. Now, do you believe me? Probably not because you recognize (as Berkeley does) that existence and perception are connected. For something to exist it must be perceived. If something cannot be perceived, it simply doesn't exist. This is what Berkeley meant when he said "Esse est percipi:" to be is to be perceived.
To say that substance exists but cannot be perceived is just nonsense. If something exists then it has to be perceived. So, since substance cannot be perceived, it doesn't exist. This of course is a radical idea and much different than the dualism of Descartes and Locke. In this respect, Locke was like Descartes. They both believed in two substances: a mental substance and a physical substance. But, we've just shown that physical substance can't be perceived. And, only things that can be perceived exist. So we have to conclude that physical substance doesn't exist. That means everything that exists is the product of mental substance. In other words, everything is just a collection of ideas. This metaphysical position, which Berkeley was championing, is called idealism.
Notice that this theory not only deals with the problem of substance (by denying its existence) it also solves the problem of representative realism. We no longer have to suppose that ideas represent objects; ideas are objects. The objects we see are nothing but a collection of ideas.
While this position does overcome the problems of representative realism, it may seem to have a few of its own (like denying the existence of material substance!). The serious problem seems to be what idealism implies. If existence is tied to perception then what happens when nobody perceives an object? Does it just disappear? For example, right now I don’t perceive my car and if no one else is either then it seems that it doesn't exist. This is very much like the old question "If a tree falls in the forest and no one is there to hear it, does it make a sound?" So, do objects pop in and out of existence? Well, theoretically yes, unless there is some mind constantly perceiving them. Before we address this we should probably investigate one of the motivations for Berkeley's idealism.
Let's consider the alternatives. We've seen dualism and the problems it entails. While it’s tempting to dismiss them out of hand it seems that dualism is inherently problematic and unworkable. The other option is materialism. Granted, it solves the problem of interaction but considers some of its broader effects. Despite Hobbes' claim that materialism leaves room for God most materialists to recognize that, taken to its logical conclusion, this theory eliminates the need for God and His existence. This implication was unacceptable to Berkeley. There has to be a way to avoid the problems of dualism and the atheism of materialism. Thus, we arrive at the theory of idealism. So what do we do about the problem of existence? What we need is a universal perceiver who is always assuring the continued existence of objects even when we don’t perceive them.
The solution Bishop Berkeley (did I mention he was a Bishop?) was to offer to all these problems was ingenious. According to Berkeley, we can infer the continued existence of objects from observation. For example, if I light a candle and then leave the room, when I come back later it’s burned down. So it seems that it has been in existence even though we haven't perceived it. But for this to be true someone must be observing it; a universal perceiver. By now, of course, you've guessed that this universal perceiver is God. Quite simply this seems to be the only explanation that consistently works and solves the problems. To be an empiricist in epistemology implies that you must be an idealist in metaphysics. So what is the answer to the tree falling question? Yes, it makes a sound because God perceives it!
Interestingly enough one of the founders of quantum physics recognized that appearance and reality really may be connected. Werner Heisenberg realized that from a quantum standpoint, things don't exist unless we observe them. This seems to be implied by Heisenberg's uncertainty principle. When we observe subatomic phenomena we change what happens to them. There's no way for us to tell what subatomic particles are doing when we're not observing them. For all we know they may be doing nothing at all; they may not exist. By observing the particles we may bring them into existence. Needless to say, Heisenberg was a big fan of Berkeley! But as we'll see next, things are about to get much worse for empiricism and where it takes us. Stay tuned.