20 May '08 02:15>
Originally posted by epiphinehasWe cannot be certain about the truth of any proposition, even the proposition that nothing is certain. Sometimes uncertainty is totally unthreatening and practically irrelevant, other times it is not. I have such overwhelming evidence that my apartment will be where it was this morning that it would be unreasonable for me to be doubtful on my way home, or to call my neighbor to confirm that it is still there, or... But different propositions can be more uncertain than this, and this will be practically relevant in obvious ways in deciding what to do. Deductive logic is useful because, as far as we can tell, it invariably gets things right. We have no reason to doubt that deductive inferences are necessarily truth-preserving. In fact, we cannot imagine these inferences not being necessarily truth-preserving. We have little reason to doubt that strong inductive inferences will yield false conclusions, as long as we take the appropriate steps to ensure that our inductive base is broad and not confounded. Both seem pretty clearly useful.
If we cannot know with certainty even the putatively self-evident, then what can we know with certainty? I guess what I'm trying to get at is, what is the practical effect of such uncertainty? In our every day lives we take many so-called facts for granted, e.g., that the car is where I left it, that I will wake up in the morning, that orange ju ...[text shortened]... f we cannot rely upon logical absolutes to be absolutely certain, then of what use is logic?