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Al-Ghazali on Skepticism

I'm currently reading Al-Ghazali's spiritual/philosophical autobiography for the first time. The translation I found in the library gives the title as Freedom and Fulfillment, but the book is better known in English as Deliverance From Error. I'm sure this has been noticed before, but the discussion of skepticism near the beginning of the book can be interestingly compared with some of the well-known discussions of skepticism in European philosophy. Here's a quick outline.

Al-Ghazali states that he is looking for a kind of "certain knowledge" that will guarantee "safety from error" (§8). He recognizes that "the dicta of authority" (i.e., reliance on what one has been taught) cannot provide this, and therefore hypothesizes, quite plausibly, that "sense-data and the self-evident truths [of reason]" might provide this kind of certainty and safety (§9). He proceeds to examine this hypothesis by seeing whether he is able to induce doubt about these sources. It is easy enough to induce doubt about the senses because causes of sensory illusion are widespread (§10). He therefore rejects sense-data as a source of knowledge, and resolves to rely on pure reason alone.

So far, this looks interestingly similar to Descartes, but this isn't too surprising since there are ancient skeptical sources, known to both Descartes and al-Ghazali, that make similar moves. The first really interesting thing is what happens after al-Ghazali has rejected sense-data:

Then sense-data spoke up: "What assurance have you that your reliance on rational data is not like your reliance on sense-data? Indeed, you used to have confidence in me. Then the reason-judge came along and gave me the lie. But were it not for the reason-judge, you would still accept me as true. So there may be, beyond the perception of reason, another judge. And if the latter revealed itself, it would give the lie to the judgments of reason, just as the reason-judge revealed itself and gave the lie to the judgments of sense. The mere fact of the nonappearance of that further perception does not prove the impossibility of its existence." (§12)

It is interesting to compare this argument with both Descartes and Reid. In the first place, it bears some resemblance to Reid's famous 'same shop' argument: al-Ghazali, like Reid, notes that the skeptic who uses this procedure is treating reason as a higher faculty capable of judging the senses. This, of course, is something that is quite explicit in Descartes. Reid's move is to question the legitimacy of this assumption: since reason and sensation "came both out of the same shop" there is no justification for treating one as 'higher' than the other. Al-Ghazali's objection is different. He assumes that the skeptic is right to think of the faculties as arranged hierarchically so that reason rightly overrules sensation. His question is: if, from the perspective of some higher faculty, sensation turns out to be defective, could there not be some higher faculty than reason that in turn judges it to be defective? Descartes has an answer to this. According to him, divine benevolence assures that none of our faculties lead us into error in a way that cannot be corrected by a higher faculty possessed by us and, he thinks, we reflectively know what faculties we possess. But this response is no good for two reasons. In the first place, the higher faculty that judges reason might judge the arguments for divine benevolence to be faulty. In the second place, Descartes is appealing here to a faculty of reflection whose reliability has not been given any justification.

Al-Ghazali continues:

For a brief space my soul hesitated about the answer to that objection, and sense-data reinforced their difficulty by an appeal to dreaming, saying: "Don't you see that when you are asleep you believe certain things and imagine certain circumstances and believe they are fixed and lasting and entertain no doubts about that being their status? Then you wake up and know that all your imaginings and beliefs were groundless and unsubstantial. So while everything you believe through sensation or intellection in your waking state may be true in relation to that state, what assurance have you that you may not suddenly experience a state which would have the same relation to your waking state as the latter has to your dreaming, and your waking state would be dreaming in relation to that new and further state? If you found yourself in such a state you would be sure that all your rational beliefs were unsubstantial fancies." (§13)

This suggestion is interestingly different from Descartes's discussion of dreaming. Al-Ghazali assumes that when dreaming we employ a kind of dream-sensation and dream-intellection which delivers to us beliefs that are true in the dream but not true in reality. The skeptical hypothesis al-Ghazali introduces is that perhaps there is some state X such that X is to waking as waking is to dreaming. If so, then the deliverances of waking-sensation and waking-intellection would be judged to be unreal from the perspective of X-sensation and X-intellection. Al-Ghazali goes on (or rather his sense-data go on) to suggest that this state X may be achieved in Sufi spiritual practices or in the afterlife. (On the latter suggestion, compare this interesting recent paper by Gabriel Citron.)

Al-Ghazali's dream hypothesis is more powerful than Descartes's in two respects. In the first place, al-Ghazali thinks there is such a thing as dream-intellection (or dream-reason) which can be mistaken. It seems to me that something like this must be admitted to account for the phenomenon of dreaming-that. Dreams (at least for me) do not consist only of sensory experience. It is also possible to dream that a proposition is true, even if there is no sensory evidence for that proposition in the dream, and sometimes even in cases where it's hard to see what would count as sensory evidence. For instance, I once dreamed that metaethical platonism was false. This does indeed seem to be similar to 'intellection' or rational intuition—i.e., Descartes's clear and distinct perception! That is, you just see that something is true, and, indeed, perhaps it really is the case that, necessarily, if you intuit it in this way then it is true—in the dream. But of course that doesn't mean it's actually true (although I'm pretty sure metaethical platonism really is false).

The second way in which al-Ghazali's dream hypothesis is more powerful than Descartes's is that al-Ghazali is not suggesting that we simply think we're awake when we're actually asleep. For Descartes, that supposition leads to a crucial limitation of the dream thought experiment: dreams only recombine materials first perceived in waking life, so the supposition that I've always been dreaming is, according to Descartes, not coherent. But al-Ghazali's analogy is not subject to this limitation. The hypothesis is that there might be a possible standpoint that is epistemically superior to our waking standpoint in the same way our waking standpoint is epistemically superior to our dreaming standpoint. But from our waking standpoint we rightly judge that our dream beliefs are unreliable, so someone who occupied such a standpoint would be correct to judge our waking beliefs unreliable.

Two final notes about this aspect of al-Ghazali, in relation to analytic philosophy. In the first place, al-Ghazali's analogy captures something that I think intuitively troubles most people about Putnam on brains in vats. Putnam argues on metasemantic grounds that I cannot coherently suppose that I have always been envatted, since my concept vat is derived from my sensory experience. An agent who had always been envatted would speak vat-English (rather than English), and in vat-English the word 'vat' refers to an element in a computer simulation, and the agent is not a simulated brain in a simulated vat. Al-Ghazali's suggestion, though, is that we can understand the hypothesis that there exists an epistemically superior perspective which judges our beliefs in the way we judge the beliefs of actual brains in vats.

Of course one possible response to this is: who cares? Al-Ghazali actually concedes that dream beliefs are (generally) true in the dream, so this analogical dream/vat hypothesis doesn't change the fact that our beliefs are mostly true in the (unreal) world we inhabit. But al-Ghazali, at least, is troubled by the idea that our world might be unreal in this way.

In the second place, al-Ghazali's analogical argument bears an interesting resemblance to the pessimistic meta-induction. The pessimistic meta-induction (at least in one formulation) assumes that our present epistemic standpoint, with respect to science, is superior to certain past standpoints, and from this superior standpoint we judge the beliefs of those who occupy the inferior standpoints to be false. But we should believe that future standpoints will be superior to ours and will likewise judge our beliefs to be false.

Posted by Kenny at February 5, 2020 12:46 PM