Reading Group: David Macarthur, 'Naturalism and Skepticism'
Hume was unambiguous about the skeptical consequences of his naturalism. According to him, all mental processes are causal processes. If all mental processes are causal processes, then subjective experiences are intramental effects of some cause. Intramental effects can be produced by an infinitely large number of causes and for that reason do not allow us to tell what their actual effective causes were. So it may be the case that, contrary to our presumptions, none of these causes issues from the external world. This causal theory of experience results in a systematic mismatch between mind and world which leads to external world skepticism.
Naturalism shares Hume’s premiss but seeks to avoid the conclusion. All attempts to do this, Macarthur argues, are dogmatic in one way or other. (Before he turns to representative naturalistic responses to external world skepticism, he rejects inference to the best explanation as a suitable anti-skeptical instrument. Even if references to the external world explain best what makes our experiences coherent, these reference are pointless if our subjective experiences are not coherent, as seems to be the case on the causal theory of experience. This is simply to reinforce the point that if inference to the best explanation is one of the most powerful tools of naturalism, it cannot hope to refute the skeptic but must settle for the quietist option.)
Macarthur discusses three representative examples for naturalistic responses to external world skepticism. These are
(1) Quine’s position that skepticism cannot doubt all of knowledge at the same time. As far as skepticism merits an answer, there is common ground with science – those bits of empirical knowledge which are not currently in doubt. External world skepticism doubts all of knowledge and thus is unanswerable.
(2) The reliabilist view that replaces rational justification with a causal account of belief formation. If beliefs are produced by reliable processes, we can have true beliefs about the external world without having a subjective experience of its justification. So the skeptic’s view that there is no external world because we do not have rationally justified knowledge of it is badly motivated.
(3) Finally, Strawson’s interpretation of Hume according to which the belief in the external world is natural, not rational. Although what the skeptic says against the external world is intelligible, the lack of rational justifications for beliefs in the external world does not affect the natural commitment to this notion.
Macarthur finds all these responses unsatisfactory. Here are (what I take to be) his main reasons for this assessment:
(ad 1) It is wrong to assume that external world skepticism doubts all of knowledge. It just doubts knowledge about the external world. So external world skepticism is answerable by naturalist standards.
(ad 2) Reliabilism may have a point on possible knowledge. But actual knowledge involves some subjective experience of justification. So the skeptical point retains its force. Furthermore, reliabilism cannot properly account for the reliability of belief-forming processes. Reliability is either posited dogmatically as the property of some process, or accounting for it leads to infinite regress because reliability is accounted for in terms of other reliable processes.
(ad 3) Natural belief cannot be revised or confirmed empirically. This contradicts naturalistic principles. Then, the notion of natural belief obscures the connection between belief and reason. Contrary to assumptions or hypotheses, Macarthur claims, beliefs are always open to rational criticism. External world criticism, like any other skepticism, insists that beliefs be given up if they become untenable. Strawson’s Humean “natural belief” is untenable by these standards.
Macarthur concludes that these representative naturalistic responses fail to stop the Humean move from naturalism (his causal theory of experience) to skepticism. Naturalism has not shown that the skeptic need not be refuted and therefore begs the question against the skeptic. So quietism on naturalist terms is not a viable solution.
Just two quick observations:
(I) Part of Macarthur’s point against (2) is that accounts for reliability are infinitely regressive. But this may not be as damaging for reliabilism as he seems to think. The accuracy of inductive reasoning may be enhanced by further induction (Popper, not Hume). Similarly, subsequent reliable processes may have corrective effects on the original process. So reliability may not be the dogmatic notion as which Macarthur portrays it.
(II) Macarthur suggests that external world skepticism withstands all these responses. However, to withstand them, it has to be modified in each case. The skepticism that survives (1) is not the same as the skepticism that survives (2). As (1) and (2) can be held jointly, naturalism might try to corner external world skepticism by combining these responses. I hope I can make this a little clearer:
To manoeuvre external world skepticism past (1), the skeptic must accept that there is some rationally justified knowledge, just not that about the external world. If positioned against (2), this appears to amount to the concession that there is some actual reliabilist knowledge – as there is rationally justified knowledge about something, though not the external world, the reliability of the process by which this knowledge is reached is confirmed as well. It does not seem impossible, then, to expand this reliable process tentatively, to close the causal gap between mind and world and to include beliefs about the external world. These cannot be not true because the process is unreliable, and this seems to hold regardless of the availability of rational justifications for them.
Labels: Hume, Naturalism, Scepticism
posted by Anonymous at 11:34 pm
3 Comments:
I'm pretty unimpressed by the 'intuitive' move from naturalism to scepticism. Let's start with, what I take to be, a relatively clear error in fn.30. Here Macarthur claims that the causal model of expeience, that he has suggested naturalists must subscribe to, is not committed to a 'highest common factor' view of experience. And he justifies this by claiming that it might take intentionalist or adverbialist forms. But these are surely highest common factor views! The highest common factor being, "an inner component that carries not existential commitment to the existence of any external object (call this subjective experience)" (111). As such, fn.30 is just astonishing. 'Subjective experience'does rule out disjunctivism, so we might wonder whether it is right to suppose that disjunctivism is inherently non-naturalistic.
In the next section, this surfaces again. Here I quote:
"The idea that the very same experiential states, when considered from the first-person perspective, could have been produced by one of an indefinately large number of sets of causal antecedents, strongly supports the view that the content of such states does not depend upon any conditions external to one's mind." (113).
No self-respecting disjunctivist would have any truck with this. Nor with his replacing of Hume's 'perceptions' with his own 'subjective experience', to yield: "the mind has never anything present to it but subjective experiences". Even an intentionalist will baulk at that.
So, as far as I can tell, what we have is the presupposition that naturalists are committed to a highest common factor view and the ensuing claim that they must be individualists. For the record, I doubt the first assumption is defensible, and also that individualism is entailed by it.
Perhaps what I've been calling an presupposition is actually based on Macarthur's claim that naturalists are committed to a causal account of the mind, alongside his claim that, "most contemporary naturalists would say that these causal [mental] states, events and processes are realized in the brain or body." (110). Well you might think that individualism is supported by a local supervenience claim. But why think that a naturalist need be committed to a local, rather than a global, supervenience claim? A disjunctivist or externalist can think that the mental globally supervenes on the physical. Why is that non-naturalistic?
But why does any of this matter? Because disjunctivism or externalism change the lanscape when it comes to answering scepticism. For supposing one of them to be the case, we could not say that, "the very same experiential states, when considered from the first-person perspective, could have been produced by one of an indefinately large number of sets of causal antecedents". So neither could we say that, "we are caused to have the very same subjective experiences by some peculiar power of our own minds" (113). For they would not be 'the very same'. Contrary to Macarthur's claim, cases such as hallucinations would be required - and the argument would have to be based on something like the concept of knowledge requiring us to be in a position to rule out perfect hallucinations. But this is a very different argument than the one Macarthur sketches. And the difference is clearly destructive of his comments on Quine.
A final comment on Quine and circularity. Quine's view (and subsequently Maddy's) seems to be that we test the reliability of sense perception by empirical means. Earlier, Macarthur says this:
"Once perception is thought of as an awareness of a subjective experience whose cause may be any one of indefinately many causes, then the claim that the cause is the external world rather than whatever it is according to one or other of the skeptical hypothesies seems dogmatic and ad hoc" (114). Why so? Putting aside the point that 'the external world' is a sceptic's term and a naturalist will probably rather claim that the causes of our expiences are the various physical objects in our environment, surely there is all the empirical evidence supporting the one option, and nothing but bare possibility in favour of the other? Of course, the sceptic will reply that this is circular (rather than ad hoc), as empirical evidence is, itself, based on sense perception. Yes, partly, but we are talking about highly intricate and sophisticated theories of, let's say, visual processing which are, to put it mildly, not JUST based on vision. The point is, the circularity charge needs to be fleshed out considerably further before it will convince me.
I have a few questions about the difference that disjunctivism is supposed to make.
If I understand this position, two connected points seem essential for its attitude to skepticism. (1) For disjunctivism, genuine perceptions and illusions are mental states that although subjectively indistinguishable, are not (based on) mental states of a common kind. Conventional external world skepticism assumes that there is no external world, because illusions about that world can be mistaken, in subjective experience, for genuine perceptions of that world. This implies that genuine perceptions and illusions are (based on) mental states of a common kind. Disjunctivism denies this. Therefore conventional external world skepticism fails to pose a challenge to the disjunctivist view.
(2) If we combine disjunctivism with naturalism, genuine perceptions and illusions are (based on) mental states that supervene on physical states. As illusions are subjectively indistinguishable from genuine perceptions, they may also be thought of as supervening on the same brain state as genuine perceptions. Both mental states can still be told apart, however, because genuine perceptions supervene on a brain state plus an environmental state, whereas illusions supervene on a brain state only. So we are not stuck with individualism.
(ad 2) How do we get to the assumption that a global supervenience base is available in the case of genuine perception? A hallucination of a double-decker bus and the genuine perception of it are not just subjectively indistinguishable. They supervene on scientifically indistinguishable brain states, for instance. So neuroscience doesn’t seem to help, and something else is needed. What, though, if the environmental situation is such that there is no distinction between the global and local supervenience base (in a brain-in-vat scenario, say)? In that case, it doesn’t seem to matter whether genuine perceptions and illusions are (based on) different kinds of mental states. They supervene on the same physical state, and they are subjectively indistinguishable. But then I don’t see why their lacking scientific distinctiveness should take precedence over, or indeed be considered something separate from, their lacking subjective distinctiveness. That is, I don’t see why one should hold on to the disjunctivist view that subjective experience is of no further significance to the problem of perception. And this, I take it, opens the door to individualism again.
(ad 1) The less conventional skeptic will also explore the possibility that the illusion side of the disjunction is idle so that the disjunction ceases to be a genuine disjunction. As far as I’m aware (evidently that doesn’t amount to much) disjunctivism defines illusions as (based on) a kind of mental state whose only definitive characteristic it is that it subjectively looks like another kind of mental state, namely a genuine perception. It is not essential to this other kind of mental state that it subjectively looks like another kind of mental state (though it does, of course). It is a perception of properties instantiated in mind-independent objects. Illusions, on the other hand, seem to be left, by disjunctivism, to some representationalism by default. Hence the incommensurability (if that’s the right term) between both kinds of states. It might be suspected, though, that disjunctivism solves the problem of perception by elegantly passing over illusions. The skeptic insinuates that if illusions were to be given some more explicit treatment (e.g. by stating what hallucinated properties are instantiated in or which environmental aspects should be taken into account in addition to brain states as a supervenience base for illusory mental states) another common kind would surface. Wouldn’t this lead back to the conventional picture where subjectively indistinguishable cases give rise to skeptical doubts?
So disjunctivism indeed changes the scenery for skepticism, but I don’t think it changes the game very much. I don’t think, in particular, that it helps the naturalist ignore the conventional skeptic. (I’m not defending Macarthur’s way of stating how naturalism implies conventional skepticism.) What am I missing?
Hi Christian,
I'm not sure that I understand everything you say, but I don't think we disagree very much. According to the disjuntivist view, when I perceive a bus I am related to a bus. Thus disjunctivism denies that perceptual states supervene on brain states - busses are required too. This means that the brain in the vat doesn't have perceptions, just apparent perceptions.
Now, I wasn't offering an argument for disjunctivism, or saying that disjuntivism answers all sceptical challenges. Unlike McDowell sometimes seems to suggest, I think that disjunctivism fails to answer all forms of scepticism about perceptual knowledge. In particular it doesn't undermine the sort of sceptical challenge that points out that hallucinations might be subjectively indistinguishable from the real deal, then requires us to be able to rule out the possibility that we are in such a situation in order to obtain knowledge via perception. But I do think that it undermines the sort of scepticism that begins from the idea that that which I am aware of in perception falls short of the bus itself. The question is, would Macarthur's argument get undermined by disjuntivism, and my contention is that it would. It strikes me that supposing that disjuntivism is endorsed, scepticism about perceptual knowledge is going to have to be motivated by considerations concerning the nature of knowledge (e.g. that you must be in a position to rule out alternatives), not the nature of experience. But this isn't how Macarthur proceeds.
Post a Comment
<< Home