Two is just a concept
Bertrand Russell, one of the greatest mathematicians of our age, and perhaps of all ages, has written a book, PRINCIPIA MATHEMATICA. It takes him two hundred and fifty pages to go into the question, whether or not two plus two is four. You cannot even conceive what he will be writing in two hundred and fifty pages .... Two plus two is simply four and forget all about it. Two hundred and fifty pages ...such a dense, logical argumentation that his book is one of the most unreadable books in the world.
Just a few crazy people, who don't care whether it is readable or unreadable .... in many university libraries the book has not even been opened. Many pages are joined -- nobody has cut them, because even to read two pages is enough! It is one thousand pages in all and one-fourth has gone only in discussing whether or not two plus two is four.
And the conclusion? The conclusion is that it is only a belief. It cannot be said with certainty, that two plus two makes four. It is a utilitarian concept. It is good, workable, but Bertrand Russell has not been left unchallenged -- even on that. Another mathematician, Godel, challenged it. Because Godel says there is no possibility of two plus two being four. There is no possibility at all. And Godel has the same quality of genius as Bertrand Russell. He is not in any way a smaller genius -- perhaps a greater genius. His argument is very clear and Bertrand Russell has not been able to answer it.
Godel argues that you can put two chairs and two chairs together and naturally, there are four chairs. but two in itself is just an abstract symbol. Two chairs is another matter. Two is just a concept. It is as hypothetical as God, or the devil. Have you seen two anywhere? Have you met with two and said hello? Have you ever seen two with two meeting and hugging each other?
And Godel's criticism is that two things in existence are never exactly the same; something is always different. You cannot find two people the same; you cannot find even two leaves in the whole forest exactly the same. Then how can two leaves which are not equal, together with two other leaves which are also not equal, be four? They can be three, they can be five, they can be anything, but not four!
And Godel is right. Godel is more appealing because that makes existence mysterious. You cannot even count on such simple answers as two and two are four. Everything is pragmatic. But as far as reality is concerned, it remains unknowable.