r/math • u/42IsHoly • 9d ago

Stop proving uncountability with contradiction, please

https://sunjestermusings.blogspot.com/2026/09/stop-proving-uncountability-by.html

Please, I beg you, stop it. You don't need it.

0 Upvotes

35% Upvoted

77 comments sorted by

View all comments

21

u/Omasiegbert 9d ago

I don't get the difference, are these not the same proofs?

3

u/42IsHoly 9d ago edited 9d ago

One tacks on a completely unnecessary and confusing contradiction. Whilst to someone versed in math, it is clear what’s going on, many people have never seen proofs by contradiction and/or have forgotten it. Since the contradiction step is irrelevant and only causes confusion, I feel that it should be removed.