715 karma · joined December 15, 2013
And according to the first sentence of the summary the current formulation is axiomatic as well...
Also, I do think that physics is pretty axiomatic right from it's roots. Newton's main inspiration for forming his theory is the work of Euclid, i.e. first formal system that was ever created.
Actually, there is no "neither true nor false" in intuitionistic logic as well, because there is no True and False in a first place. There is only Proven and not Proven.
Don't think in terms of true and false, think in terms of proofs
"If we view classical logic as based on set theory, then intuitionistic logic would be based on category theory and its related theories."
And regarding the fact that CT is not "needed" for algebraic logic what I say is "category theory and its related theories." where I consider orders related to categories.
Regarding the psyche part, I have actually written an article about that which might change your opinion https://boris-marinov.github.io/logic-thought/
For logic, it really depends of what you are searching for, for classical logic you can read the the classics, for example Russell and Tarski.
For constructive logic I cannot think of a good introduction (besides mine ;) ), I personally picked it up from books about category theory and computer science.
1. Ordering is not required for a category to be a category, the necessary requirements are just the ones listed in the beginning of the book. It is just that orders can be seen as categories.
2. You can express "A or not A" in intuitionistic logic it is just that it is not necessarily true. Also, not sure how would you express that or any logical relation in set theory.