David Hume

David Hume thought that we could never be sure of our knowledge of the world. It is just perception. We can't know that the sun will rise tomorrow just because it rose yesterday and the day before. That's an inductive fallacy. Thomas Reid tried to take Hume to task by asking, if we can't trust our senses, what can we trust? This doesn't get us far. The real answer is in how complex the universe is likely to be. To have everyone have vastly different perceptions to such a degree that we can't read a thermometer or clock, we would need one of two things: either a complex universe that can change how thermometers work from moment to moment, or we would need brains that have simultaneously evolved that can perceive in vastly different ways -- your blue is not my blue because you are actually seeing something different from what I am seeing when I see blue.

Hume also thought that there could not be a self that exists over time. The self clearly is a tricky thing. But modern brain science shows that memories are indeed stored in the neurons. False memories are not a problem here because they are anomalous. The point is that we do have memories and they do stay with us. I don't argue that Hume totally misses the mark. Again, the self is a dicey concept, but some sort of self does exist over time unless disease or damage occurs. Hume's contention that there is no self is the falsehood here, not that the self is not at all fungible. We should note that Hume's problems with induction seem a bit silly in the face of a universe that has light traveling steadily for tens of billions of years. Why should we have doubts about the future, in a Humean way, that don't seem to apply to the visible past? Hume would have to come up with some sort of vector for this sudden and inexplicable change he proposes is possible.

Also Hume says that there is no reason to prefer avoiding the destruction of the world over scratching his finger. The problems here are with the words reason and prefer. By reason does he mean a method of proof? Can we prove that the destruction of the world is less preferable to scratching an itch? We can prove that we would like it less. We would not want to see fear and pain in ourselves or others. Fear and pain are not things that we generally prefer. Can we prove that we should not? Is that necessary to show that Hume has tied himself in a knot? I doubt it. We could not make the vast majority of people prefer destroying the world over scratching one's own finger. Had Hume acknowledged this fact I feel that he would have been making some progress. As it is, he again is not accurately describing the world. He is forcing a needless skepticism on himself. I don't think in ethics we can know what all the wrong or right actions are. But that doesn't mean that we know nothing about right and wrong.