Philosophical atheism: uses philosophy to justify non-belief. Philosophical atheists have not shared a common set of atheism no god or gods exist views, philosophical convictions can often set them off from other groups of atheism thinkers. There are different kinds of philosophical atheists as well as many philosophical justifications for atheism. Many rationalist atheists feel that the idea of a god something as presented by the major religions is essentially self-contradictory, and that it is logically impossible that such a god something could exist. Others are atheists through skepticism, because they see no evidence that a god something exists. Of course, some people are atheists without having any particular logical argument to back up their atheism. For some, it is simply the most comfortable, common sense position to take. Philosophical atheism is different addressing one of agnosticism’s biggest objections the limit to knowledge a god something exists or agnosticism’s believed impossibility to prove the nonexistence of something.
There are many counterexamples to prove the nonexistence of something. For example, it is quite simple to prove that there does not exist a prime number larger than all other prime numbers. Of course, this deals with well-defined objects obeying well-defined rules. Whether a god somethings or universes are similarly well-defined is a matter for debate. However, assuming for the moment that the existence of a god something is not provably impossible, there are still subtle reasons for assuming the nonexistence of a god something. If we assume that something does not exist, it is always possible to show that this assumption is invalid by finding a single counterexample. If on the other hand we assume that something does exist, and if the thing in question is not provably impossible, showing that the assumption is invalid may require an exhaustive search of all possible places where such a thing might be found, to show that it isn’t there. Such an exhaustive search is often impractical or impossible.
There is no such problem with largest primes, because we can prove that they don’t exist. Therefore it is generally accepted that we must assume things do not exist unless we have evidence that they do. To assume that a god something exists is to make an assumption which probably cannot be tested. We cannot make an exhaustive search of everywhere a god something might be to prove that he doesn’t exist anywhere. If a god something interacts with our universe in any way, the effects of his interaction must have some physical manifestation. Hence his interaction with our universe must be in principle detectable. If a god something is essentially undetectable, it must therefore be the case that he does not interact with our universe in any way.
Many atheists would argue that if a god something does not interact with our universe at all, it is of no importance whether he exists or not. A thing which cannot even be detected in principle does not logically exist. Things do not exist merely because they have been defined to do so. We know a lot about the definition of Santa Claus–what he looks like, what he does, where he lives, what his reindeer are called, and so on. But that still doesn’t mean that Santa exists.