If science cannot prove the non-existence of something, why do scientists use the term "extinct"?

Question

Seems intellectually sloppy. Is "presumed extinct" used commonly? I'm really just a lay-person, and my presumption could be inaccurate.

Answer 1

Extinction is applied only after a species hasn't been recorded for a specified period of time (commonly 50 years) and only after an adequate search has been carried out. It has a very specific meaning. Essentially when a species is declared extinct it means that there is very good reason to believe it is extinct.

Presumed extinct is used fairly regularly. It means that there is reasonable grounds to assume extinction, but either the requiredtime period hasn;t elapsed or for one reason or another exhaustive searches can't be carried out. Presumed extinct is usually applied either to species that were never well known, so it's impossible to know where to focus a search, or to species that inhabited rugged regions or war zones so that thorough searches are impossible.

Answer 2

Some animals are extinct, but scientists have records and have proven that they once lived. For example, some animals are endangered right now, like the pandas, and if they become extinct, they do not exist anymore, but scientists can prove they once existed.

Answer 3

Well all things are tentative anyway.