Back in 1641, or maybe 1639, René Descartes asked whether he (and therefore we) might be seriously mistaken about some pretty important stuff, i.e. everything:
I have for many years been sure that there is an all-powerful God who made me to be the sort of creature that I am. How do I know that he hasn’t brought it about that there is no earth, no sky, nothing that takes up space, no shape, no size, no place, while making sure that all these things appear to me to exist? Anyway, I sometimes think that others go wrong even when they think they have the most perfect knowledge; so how do I know that I myself don’t go wrong every time I add two and three or count the sides of a square?
… I am driven back to the position that doubts can properly be raised about any of my former beliefs…. So in future, if I want to discover any certainty, I must withhold my assent from these former beliefs just as carefully as I withhold it from obvious falsehoods.
So I shall suppose that some malicious, powerful, cunning demon has done all he can to deceive me – rather than this being done by God, who is supremely good and the source of truth. I shall think that the sky, the air, the earth, colours, shapes, sounds and all external things are merely dreams that the demon has contrived as traps for my judgment. I shall consider myself as having no hands or eyes, or flesh, or blood or senses, but as having falsely believed that I had all these things. I shall stubbornly persist in this train of thought; and even if I can’t learn any truth, I shall at least do what I can do, which is to be on my guard against accepting any falsehoods. [Meditations on First Philosophy]
Then, about a month ago, Stan Persky responded to Descartes in the Los Angeles Review of Books:
I’ve always been uneasy with Descartes’ insistence on certainty, at least with respect to ordinary human experience (and to a range of moral questions) …
How can we be sure the whole thing isn’t a dream or simulation or parallel universe? Answer: we can’t be sure, but why do we have to be sure? Why do we have to prove the Demon wrong? And anyway, isn’t the claim about the Demon’s deception so extraordinary that the burden of proof ought to rest on those making the claim that there is a Demon? Why isn’t “pretty sure” that I’m not now dreaming good enough? Given that our perception and interpretation of reality is supported by a) generally reliable sensory evidence, b) intersubjective human agreement, c) “scientific” explanations and evidence, and d) absence of evidence that anything else is going on, why isn’t that good enough for most of our purposes?
Answer #2: It’s good enough. We don’t have to be certain.
(This blogging thing can be pretty darn easy.)