Nuts and Bolts: enthymeme.

An enthymeme is a matter of logic.

Sometimes.

To get an enthymeme you have to start with a syllogism. A syllogism is a statement where you deduce a fact as a result of stating and then accepting two others. 

Dogs are mammals.
Snoopy is a dog.
Therefore, Snoopy is a mammal.*

If you don't bother to state one of the supporting facts then you've got an enthymeme:

Snoopy is a mammal because he's a dog.

But there are other types of enthymeme, and some of them are very weak indeed. You can have an enthymeme which relies on a sign of something to bring you to a conclusion:

She's wearing fur, therefore she's not a vegan.

which is usually true - but not, for instance, if the she in question is a hamster.

Weaker still are the enthymemes which are based on prejudice - though these do come in very useful for jokes:

I can always tell when my mother-in-law's coming to stay: the mice throw themselves on the traps.
Les Dawson.

It may take a while to unpick the logic in that statement, but over the years it's still made a lot of people laugh.

Thing To Consider Today: enthymeme. The Greek word enthumeisthai means to infer, from thumos, mind.

*Which just goes to prove that even logic isn't necessarily completely bullet-proof.