Posted: May 17, 2012 9:15 pm
amkerman wrote:Classical logic requires that each term denotes an existing object.
If square circles are defined as things which can't exist, the statement "if God(exists) then God is a square circle" is false, and the argument is invalid in classical logic from the start.
http://en.wikipedia.org/wiki/Term_%28logic%29
The important thing to notice here is that "God" is not a constant symbol, variable or function symbol of the language and nor is "square circle", they are formulae. They would be constructed from terms which do not have empty domains. This is simply not a problem. You have just confused the technical meanings of "term" and "formula".