[asgardshill]

I believe they have values (and they have value as well), but the last condition distilled out of all those values (x number of communicating civilizations) is unproven and therefore bunk. Just because the conditions exist to support something doesn't mean that it logically follows that "something" does indeed exist.

[Physicist]

Alien civilizations don't have to exist for the Drake equation to be correct. Zero and one are perfectly good solutions.