Does Anyone Really Practice Skepticism?

I have no problem with someone who says he is "skeptical" of some proposition or theory. In everyday talk, that just means the person has doubts about a claim. It may not mean that he doubts it, just that he has doubts about it, which seems different. The first seems to imply a rejection or a near-rejection of the claim; the second seems softer. "I doubt it" differs from "I have doubts about it."

Be that as it may, I am dubious about using the term skepticism to mean mere doubt. Making doubt into a ism is an entirely different ballgame. An ism suggests a doctrine, and a doctrine based on doubt strikes me as strange. (For the same reason, the term atheism is weird because no doctrine flows merely from not believing in God.) In philosophy skepticism is the position that knowledge in general or knowledge of a particular kind is impossible. It does not mean a particular doubt about something. One cannot doubt everything, as Wittgenstein pointed out. Think what that would mean. To doubt a particular claim, you have to be standing somewhere; you have to know something that gives rise to grounds for particular doubt. That means that doubt cannot be general or radical. Skepticism is a dead end, a nonstarter.

"But all I mean by skepticism is that I won't accept a claim without evidence." Good policy. And there's a more descriptive name for that: evidentialism. That's a far less problematic doctrine, though you won't find a philosophy of life in it. But note: a doctrinaire skeptic wouldn't demand evidence because by his own confession knowledge is ruled out. You can't know what you can't know -- full stop.

Even a staunch evidentialist doesn't demand evidence for everything he accepts as true. For one thing, he wouldn't have the time. How many people demand proof for the proposition that matter is made of atoms, which are made up of subatomic particles? Fewer still have confirmed the claim for themselves. The overwhelming majority of people (me included) wouldn't even know how to do it. But we can confidently say we know it is true. 

The same goes for countless other things we treat as knowledge every day. How do I know that earth is part of a galaxy, which is only one of many galaxies; that salt is sodium chloride; that the carton of Morton "salt" I just bought really is sodium chloride; that glass is made from sand; that Wellington defeated Napoleon at Waterloo in 1815; that the hamburger I just ordered at a restaurant really is beef, and on and on and on? Each of us has direct proof of only the tiniest fraction of all the things we (yes) know. And that means that most of what we know we learned, that is, heard, from other people. It's hearsay! (Heresy?) Is that a problem? It can be sometimes, but usually it is not. Thanks to various processes (competition and reputation), we manage to live day to day reasonably well.

Have we taken those things on faith? That depends on your definition of faith. I wouldn't want to say we believe them without evidence; but that's because the "testimony" of reputable authorities (chemists, restaurateurs, historians, etc.) who seem to have no motive to lie and many incentives to tell the truth -- that "testimony" counts as good evidence, even if I am unable to confirm it for myself. The authorities' good names function as brand names. They have earned our trust, although that doesn't mean they are infallible. Any particular proposition is rebuttable in principle (that's where religious claims differ), but until it is credibly rebutted, accepting it as knowledge is the reasonable thing to do, if for no other reason than it does not clash with other things we know. If it all "negatively coheres" we can proceed. What's a realistic alternative?

Thoroughgoing principled skepticism is a road to nowhere. It shrinks your knowledge almost to the dimensions of a mathematical point, which is to say: to very little. So a sincere and thoroughgoing skeptic would be obliged to pretty much keep quiet. "Wherefore one cannot speak, therefore one must be silent," Wittgenstein wrote.

What's this got to do with atheism? Building a case against God on skeptical grounds is like building a house on sand. Condemning theists for believing things they have not confirmed for themselves is obviously hypocritical since we all do that all the time. But that doesn't mean we must be agnostics. We can be certain that the supernatural does not exist -- yet, strangely, not all atheists agree. Allergic as they are to the burden of proof, those atheists try never to utter a proposition. Yet despite themselves, they implicitly hold this proposition: the supernatural is possible -- without providing a scintilla of evidence.

In fact, claims about the supernatural simply cannot get past the first intellectual hurdle: the burden of coherence. Anything supernatural embodies a logical contradiction: existence outside of existence. So supernatural claims never even reach the other two hurdles: the burden of plausibility and the burden of proof. Believing in the supernatural is like believing in square circles. Skeptics don't ask for proof that A is A, do they?