What is 2 * 2 ?

Several scientists were all posed the following question: "What is 2 * 2 ?"

The engineer whips out his slide rule (so it's old) and shuffles it back and forth, and finally announces "3.99".

The physicist consults his technical references, sets up the problem on his computer, and announces "it lies between 3.98 and 4.02".

The mathematician cogitates for a while, then announces: "I don't know what the answer is, but I can tell you, an answer exists!".

Philosopher smiles: "But what do you mean by 2 * 2 ?"

Logician replies: "Please define 2 * 2 more precisely."

The sociologist: "I don't know, but is was nice talking about it".

Behavioral Ecologist: "A polygamous mating system".

Medical Student : "4"

All others looking astonished : "How did you know?"

Medical Student : "I memorized it."