I got this question from Logic, laws of truth, by Nicholas J.J Smith.

He says (page 24) :

"A connective is truth functional if it has the property that the truth or falsity of a compound proposition formed from the connective and some other propositions is completely determined by the truth or falsity of those component propositions."

I don't really seem to be able to appreciate the usefulness of truth-functional connectives.

Perhaps, I don't understand what he is saying in that paragraph, so I would appreciate any explanation of what he is trying to say and why truth-functional connectives are useful.

Also (if you want to) can you guys explain what Nicholas means when he says "...this proposition has no internal structure..."?