I'm aware of the problem but I think it's implications are often overstated by those fixated on the idea that all foundations are built of shifting sands and we can never truly know anything. I agree that we can never truly know anything but so what? Probabilities are useful and so is past behaviour, even if not infallible. Although I don't know the Sun will rise tomorrow it would be irrational for me to base a single decision on the probability that it might not so for all intents and purposes I can treat it as true. Even if it turns out not to be true and the Sun doesn;t rise tomorrow I was still correct to think that it would.Ginkgo wrote:Yes, it would be zero for practical purposes and that's what a lot of people assumed until Hume came along. By taking induction to its logical conclusion he exposed the problem that was hidden away from view. That is, there is no logical necessity when it comes to matters of fact. "All practical purposes" is not good enough when push comes to shove. Kant, one of the greatest minds of the age was forced to agree with Hume. However, he came up with his own unique method in order to try and get around the problem of induction.
It is sensible to act as though past behaviour is predictive of future behaviour unless you have good cause to question that. Even though we have all the observational evidence that humans need oxygen we also understand the biological mechanisms at work so we can say that humans need oxygen to breath. When philosophers say things like "you don't know with certainty that humans need air to breath" scientists snigger at them and then get back to the work of actually doing things that produce results. And people wonder why the likes of Hawking criticise philosophers?
I certainly never said that a human like entity could evolve to breath without oxygen. I said that it wouldn't then be human which you yourself concede by referring to it as "human like".Ginkgo wrote:As to whether a human like entity who has evolved to breath some other combination of gases actually exists somewhere eg some other solar system is a matter of debate. However the point is that if we can even conceive of such a state of affairs then this state, no matter how unlikely does not have a zero probability. Hume, Kant and Popper would all agree with me.