Those three statements are axioms, they are declarations of logical truth, not statements of truth in and of themselves. It is universally accepted within the fields of mathematics and philosophy, that these statements cannot be proven, rather they are the assertions that form the basis of further enquiry, yet in and of themselves, they are baseless. Ask any mathematician or philosopher, or check wikipedia, and they will tell you the same. In other words, they are true only because we define them as true, because it is useful to do so. In my notes I have written an exploration of the individual axioms you posted, but decided it was too long to post. If you would like to read it, let me know.