On Wed, Jul 8, 2009 at 9:04 AM, Fred lunnon <fred.lunnon@gmail.com> wrote:
Questions of empirical verifiability or internal consistency are irrelevant. Naive sets exist because Naive Set Theory exists, and that in turn because it is quite useful (even though it's wrong!). The aether exists because Newtonian mechanics exists, ditto.
I think the word existence is overloaded here. There is a sense in which phlogiston exists, because the theory that things are flammable because they contain phlogiston, which is released by burning, exists. There is also a sense in which phlogiston does not exist, and the statement "there's no such thing as phlogiston; when things burn, they are combining with oxygen, not releasing something; phlogiston (the thing which is released when something is burned) does not exist" is a true statement. I think that discussions of existence that don't make the difference between these two kinds of existence clear are not going to be useful. Andy