I’d like to say some more about questions of doubt and certainty, which were central to my recent discussion of Wittgenstein. I explored this question at greatest length in the post called “Certain knowledge”, but the conclusions there were tentative – which is to say, not certain.
To recap a little first: This question was Descartes‘s biggest passion. He wanted one and only one Archimedean point, one firm foundation that could not be doubted, on which he could build the rest of his philosophy. And to doubt that he was doubting would be self-contradictory, so the existence of his doubt and therefore of his own existence became certain. “I think, therefore I am.”
But Descartes was wrong: the existence of the thinking self can be, and is, doubted all the time. Almost all Buddhist tradition rests on just such a doubt: the self is not real. If there is an indubitable Cartesian foundation, one must take it back to “There is thinking, therefore there is being.” But is there even this? Descartes argues that to doubt one’s own doubt (or doubt one’s own thinking) is self-contradictory. To establish this point for certain, however, does require that one accept the logic law of non-contradiction – and accept it as an absolute law, brooking no exceptions ever. Graham Priest’s dialetheist epistemology denies this very point: only by allowing that certain contradictions can be true, he says, can we successfully resolve the liar paradox or Zeno’s paradoxes. Continue reading