Topics Language

Question Is is philosophicaly valid to ask (and answer) a question based on false or impossible premises? For instance, I could ask something like "If I'm sure that the baby I'm carrying is going to be an evil person, like a new Hitler, or is going to be a mass murderer of serial child molestor, what is the moral thing to do, interrupt the pregnancy or have the baby?" but the premise of this question is false/impossible because there's no way of knowing how a fetus is going to turn out as a person. How do you philosophers deal with these types of questions?

Accepted:
May 7, 2009

Comments

That a question begins from making false or impossible presuppositions does not keep us from understanding the question or responding to it with the correct (i.e., true) answer. After all, we know that I am alive today, yet we can reasonably assert things like "Had I been hit by a car while crossing the street yesterday, then I might well not have been alive today." We know what would count as evidence for this assertion (for example, facts about my anatomy, the speed of cars on the street, etc.). The fact that I was not, in fact, hit by a car while crossing the street yesterday does not prevent us from having justified beliefs about what would have happened, had I been hit by a car.

Of course, it was *possible* for me to have been hit by a car. But it wasn't possible for Fermat's Last Theorem (a certain theorem about numbers that has recently been proved) to have been false. Long before this theorem was proved, mathematicians widely believed it to be true, since no one had ever found a counterexample to it, despite having checked (by computer) millions upon millions of numbers to see if it held of them. Accordingly, we can reasonably say that had someone discovered a counterexample to Fermat's last theorem, then mathematicians would have been astonished. Now of course, such a discovery is (we now know) impossible. Nevertheless, that doesn't keep us from having good evidence that had such a discovery been made in the years before Fermat's Last Theorem had been proved, mathematicians would have been very surprised.

The examples that I have just given do not concern morality. Your example does. But the point I am making is that the fact that "the premise of the question is false/impossible" does not prevent us from having justified beliefs about what would have been the case, had that premise been true. In this respect, the case of morality is no different from the case of mathematics.