I talk a lot about Berkeley on this blog, and it has probably become clear to most regular readers that I am quite sympathetic to his position. There are a number of reasons for holding to various forms of idealism, and I have already discussed the chain of inferences which leads Berkeley to his theory. Important also is Berkeley's critique of matter, which proceeds by collapsing Locke's distinction between primary and secondary qualities (this collapse is almost universally viewed as successful by later philosophers), then applying Locke's arguments that secondary qualities are not actually in the objects to all perceived properties, thus refuting representationalism (there is a lot more to Berkeley's critique of matter than just this, but this is a big part of it). I now want to give very briefly my own primary reasons for accepting it. Besides finding many of Berkeley's arguments generally compelling, I think that there are serious problems with the alternative positions, and idealism does not suffer from an equivalent defect. This is what I will try to show in this post.
The only two alternatives to idealism I know of are physicalism (aka materialism) and dualism (if anyone knows of any views that have been proposed besides these three, please say so). Physicalism is the view that matter and/or energy (where those two terms are used in more or less the technical usages of modern physics; from now on I will simply say "the physical") is all that exists on the deepest ontological level. The physical is fundamentally real, and anything that exists which is distinct from it is ontologically dependent on it. Dualism is the view that, there is some mental or spiritual substance which is distinct from and equally ontologically basic with the physical. Idealism is the claim that this mental or spiritual substance is the only ontologically fundamental entity.
The problem with physicalism is that it is singularly bad at accounting for the most obvious and indisputable fact in our experience of the world: that our experience exists. I experience the world, and I experience it subjectively. A huge proportion of the contemporary literature in philosophy of mind is made up of attempts to explain this from the perspective of physicalism. I regard this as essentially a lost cause. It just isn't happening. The best argument to this effect with which I am familiar is David Chalmers' "functional isomorph" (aka "zombie") thought experiment (note: I have not personally read Chalmers' original work on the subject). Chalmers simply points out that there doesn't seem to be anything impossible about a being who looks and acts in a manner indistinguishable from a human being, but does not experience consciousness. If nothing about the human body (including the brain) necessarily entails consciousness, then how could anything physical explain consciousness? It doesn't seem that it can. The physicalist approach is backward and upside down. We need to explain what consciousness and perception are before we start using perception to deduce things about the world. For this reason, we can't use perception to explain consciousness (though we may form and test hypotheses using perception).
The more natural step is to posit dualism. The dualist takes the experience of subjectivity seriously, and posits a mental or spiritual substance which is the subject of this experience. He then makes the allegedly common-sensical supposition of reliabilism. That is, he supposes that our senses provide data about a "real" physical world which corresponds to our perceptions. The problem here is, of course, the infamous mind-body problem, which millenia of philosophers have tried and failed to solve. If the physical and the mental are totally different types of entities, how can they interact? It seems that they probably can't. I only know of two real solutions to the mind-body problem: Leibniz's "pre-established harmony" and Malebranche's "occasionalism" (there may be others which I have missed due to the ancient and early modern bias of my philosophical studies thus far).
According to pre-established harmony, the physical and the mental operate according to totally separate laws and do not interact. God has simply created the relevant laws in such a way that the two separate worlds operate harmoniously. Leibniz uses the analogy of a clock-maker who wants his two clocks to always say the same time. He says that the best way to do this is simply to make the two clocks both accurate and set them to the same time to begin with. (It should be noted that, while there is some controversy regarding Leibniz's later writings, scholars generally do not regard Leibniz as actually being a dualist; but his actual metaphysical understanding is complicated and not relevant here.)
According to occasionalism there is, again, no interaction between the human mind and the material world. Instead, God acts as a go-between. God knows what's going on in the physical and causes appropriate perceptions in us, and he knows what is going on in the mental and causes appropriate movements of our bodies.
Both of these answers have the same problem: they make matter irrelevant to human existence by totally cutting off our epistemic access to it. That is, in the first case, if all matter were suddenly destroyed (on a strict Leibnizian picture of the universe, even if everything except God and myself were destroyed), I would go on having the same perceptions I would have had if matter had continued to exist, so it follows that I have no way of knowing whether matter exists. In the second case, God is really the direct and immediate origin of my perceptions (in Leibniz it is the law of my own monad unfolding over time, which God created), and God doesn't need matter in order to do this. It's not clear why God would even create matter in this case. (Berkeley makes this argument against Malebranche explicitly in several places.) So the mind-body problem may be even more difficult than a physicalist explanation of consciousness.
Does idealism suffer from a similar defect? It might be thought that it does. Idealism still needs to explain perceptions and their source. According to Berkeley's theory (which I accept on this point), that source is God. If there is already independent evidence for the existence of an omnipotent personal God, then problem solved; this is clearly something he can do. But in the absence of independent evidence, positing an omnipotent being to explain whatever can't otherwise be explained is simply unreasonable. However, as was pointed out in the post on Berkeley's argument, there are reasons to think that whatever the source is has some characteristics similar to the known characteristics of a mind, so positing something like my mind but having an additional power might be reasonable. For comparison, imagine you were living in a jungle and there is no reason why there couldn't be hitherto undiscovered animals there (it hasn't been very well explored yet), and there are only a few animals that are already known. Imagine what kind of evidence would be needed for you to justifiably suppose the existence of something like a big wolf, but with opposable thumbs, without actually seeing such a creature. This won't quite get you to God, but to a super-mind at least.
We still have problems like what is substance, how does mental/spiritual substance works (that is, e.g., how am I and how is God able to create new thoughts), but these are equally problematic for physicalists and dualists.
This set of considerations is, I believe, sufficient to justify belief (i.e. render non-belief irrational) in idealism for the already-comitted theist, and at least warrant belief (i.e. render belief not irrational) in idealism (and some weak form of theism - that is, not necessarily belief in the tri-omni God, but belief in something) for the hitherto agnostic. I'm waiting for a refutation better than Moore's.Posted by Kenny at January 4, 2007 12:12 AM
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