〜というものだ

Meaning

Expresses the speaker's judgment that, in light of the nature and reason of things, that is the way things naturally should be. Asserts, with feeling or evaluation, that something is how it ought to be, or that only then does it make sense.

Examples

困った時に助け合うのが、友情というものだ Helping each other in times of trouble is what friendship is all about.
努力が報われてこそ、頑張ったかいがあるというものだ Only when effort is rewarded is it worth having worked hard.
約束を守らないのは、無責任というものだ Not keeping promises is what you call irresponsible.