Are physical and logical truths distinct and, if so, how are they related? Is one more fundamental than the other?
By ‘physical truth’ I mean something true in virtue of the laws of physics, such as ‘masses attract other masses’ (gravity) and by ‘logical truth’ I mean something true in virtue of logical or mathematical principles, like ‘2 + 2 = 4’.
Could there be a world where some of the physical truths of our world were false but all of the logical truths of our world were true? That is, a world where masses always repelled other masses but 2 + 2 = 4?
Conversely, could there be a world where some of the logical truths of our world were false but all of the physical truths of our world remained true? That is, a world where 2 + 2 = 5 but where, as in our world, masses attract other masses?
[We’ve been discussing this hours and feel in desperate need of professional guidance - please help!]
In response to a recent question about philosophy (http://www.askphilosophers.org/question/3529/), Oliver Leaman made the claim that, "there are no facts in philosophy." Briefly reviewing the definition of "fact" I see "something that actually exists; reality; truth." Can it really be that there is no truth in philosophy? It seems like the respondent has made an assumption that it very broad, fundamental, and contestable.
I recently had an argument in an epistemology class about the relationship between facts and human minds. I argued that a fact cannot exist until a human mind knows it. Most of the rest of the class (and the professor) argued that facts can exist independently of human minds. My professor's example: Every human being believes that the world is flat, when it is in fact round. I argued that the fact that the world is round did not exist until someone thought it. Can a fact exist without a human mind?
Are there philosophers who maintain a distinction between what is "true" and what is "useful"? It seems that much of analytical philosophy and higher mathematics is true without being of much use, even to scientists. Scientists and engineers, on the other had, come up with many useful ideas whose truth values may be doubted by the abstract thinkers.
In other words, does anyone in philosophy speak of useful untruths or useless truths?