2+2=4

“Leibniz’s proof that 2 + 2 = 4 contains a gap. Grassmann’s definition of a + b is faulty”
from Gottlob Frege: The Foundations of Arithmetic

I am not crazy, and it’s a legit question :P

“A typical crudity confronts me, when I find calculation described as ‘aggregative mechanical thought’. I doubt whether there exists any though whatsoever answering to this description.”

“A proposition can be though, and again it may be true; let us never confuse the two things.”

“Est modus in rebus, sunt certi denique fines” - “There is a measure in all things”

3 laws of enquiry:
1. Always to separate sharply the psychological from logical, the subjective from the objective;
2. Never to ask for the meaning of the word in isolation, but only in the context of a propositon;
3. Never to loose sight of the distinciton between concept and object.

(from Shroder) “Abstract number, then, is the empty form of difference.”

“Hardly anything more unfortunate can befall a scientific writer than to have one of the foundations of his edifice shaken after the work is finished. This was the position I was placed in by a letter of Mr. Bertrand Russell, just when the printing of this volume was nearing its completion.”