Program Correctness, The specification

Question

From Wikipedia: In theoretical computer science, correctness of an algorithm is asserted when it is said that the algorithm is correct with respect to a specification.

But the problem is that to get the "appropriate" specification is not a trivial task, and there is no 100% correct method (as far as i know) to get the right one, it just an estimation, so if we are going to take a predicate as a specification just because it "looks" like the "one", why not taking the program as correct just because it "looks" correct?