[dj-wonk]

I'll put it this way: "perfection" is too overloaded of a word to be particularly useful in this context.

I prefer to say it this way: I want software to adhere to a contract. That implies that we want people that use the software to understand that contract. To be more precise, I'd say that:

(1) a good contract defines the scope of correct behavior.

(2) a contract may (or may not) give some bounds (or constraints) about what happens outside of the scope of correct behavior