Wednesday, September 24, 2008

The Impossibility of Halting Philosophical Inquiry

[This post was largely inspired by a hypothetical scenario and ensuing discussion at Philosophy, et cetera.]

Suppose that we have a magic device--a little black box with a screen and keyboard--which supplies us with true answers to every philosophical question we can possibly pose to it.

We can ask, e.g., "What is the true nature of the mind-body relation?" And the box might tell us, "Functionalism," (or whatever the "correct" answer is). Hurrah! In one fell swoop, we have settled a major dispute in the philosophy of mind. So, we proceed through the various fields: "Which understanding of ethics is correct?"; "What is the nature of ultimate reality?"; "What is the nature of knowledge?"; "Does God exist?". Ping! Ping! Ping! Perfectly formulated and accurate answers to each question spew out from the box. Academics everywhere can both rejoice that their long, bloody dialectical battles are over, but also mourn that now they're out of a job. Their passion--speculating about and debating abstruse philosophical topics--has lost its point, since there remains nothing further to be said.

Or does there?

The sagacious box in of itself would generate a slew of new philosophical questions to replace the old ones. In fact, it might not be adequate to answer even those traditional questions at all! Witness the following.

If there really existed such an oracular apparatus, before we even begin to think about taking it seriously, I would want to know one thing (and I think this is a very reasonable request): how can we trust the veracity of its answers in the first place? Now, this being a philosophical question, we could pose said question to the little black box itself in the hopes of receiving a satisfactory answer. But this presents a circularity problem, for no matter how the box answers, we would have no a priori reason to trust the accuracy of its answers (here a priori means less the traditional "knowable independent of experience," and more "given prior to the examination/subject at hand"). The box obviously cannot tell us, "My answers are true by virtue of their being outputted by a box that always outputs true answers." For indeed, now we are inclined to respond, "But how do we know you are one of those boxes? My dear black box, that is begging the question, plain and simple. You'll have to do better than that." In short, to answer this epistemological question, the box cannot appeal to its own authority as an infallible agent, for to do so would be circular.

In order to escape this trap, the box could try to appeal to an external, time-honored authority: reasoned arguments. Perhaps it could supply us with an airtight, incontrovertible argument to the effect that its answers are always correct. Indeed, perhaps all its answers might take this form of undeniably true premises leading irrefutably to a conclusion that no rational being could reject.

However, two things. First, is it really possible for there to be such irrefutable arguments? It seems that we can always doubt even the most basic of things, including the apparently incontestable. As Lewis Caroll pointed out in "What the Tortoise Said to Achilles," (Mind 4, No. 14 (April 1895): 278-280. Also freely available a number of places online, such as here, here, and here), nothing will force an interlocutor to accept a logical inference as valid. And we all know this, don't we? All reasoning must begin with axioms, and axioms by definition are unsupported or unjustified. So when we call something an irrefutable argument, it can only be irrefutable to some one person, or irrefutuable as considered from some one perspective (which means, starting from from a particular set of axioms and/or rules of inference). Is there such a thing as an "undeniably true premise"? Or can we reject an axiom that consists of something like, "For all A, A = A"? From what I understand, efforts have been made in the realm of dialetheism to investigate what happens if we reject such an obvious rule as the principle of non-contradiction and/or principle of excluded middle. Perhaps it is the case that there just is no such thing as an uncontroversial premise? (I realize that I am conflating premises and rules of inference a little bit in the above discussion, but the gist should be clear. I am too lazy at the moment to go back and fix things.)

Second, there might still be disagreement about understanding the logic employed by the black box. What if it spewed out proofs millions of lines long, with such convoluted chains of logic that it takes teams of experts just to have the barest idea of what is supposed to be going on, much less whether the steps are all valid or not?

To sum up, if we were unable to accept the black box's arguments at face value (and there is good reason to think that we would not be able to), we would have to resort to philosophical investigation in order to provide justification for why we should trust it in the first place. Hence, philosophical inquiry would continue, even with a magical device which, for all intents and purposes, should have ended it.

Curiously, we find ourselves in the same situation even when we replace the black box with the idea of a God.