> For example, if I say that 3+4=5 , is this a logical statement? It all depends on how you think about the question. Most of us believe that 3+4 must equal 7 becasue that is what was taught years and years ago, and therefore if the answer is not 7, it is wrong and therefore an illogical statement.

First of all, just because something is wrong doesn't make it illogical. In order for a statement to be valid, it needs two things: logical soundness and true premises. A false conclusion does not equate to a logical error. As an example:

All animals are green.
All cats are animals.
Therefore, all cats are green.

This problem is logically sound, but one of the premises is untrue. Hence the problem.

Not that it really matters, since mathematics and logic are different anyhow.