(idiomatic) A general expression of distrust, particularly implying that another person is attempting to deceive the speaker, or that a situation is not, or can not be, as it appears.

One can never be sure of one's paternity.

One should put one's mental faculties to good use.

Synonym of if all you have is a hammer, everything looks like a nail

(Internet slang) The end being pursued is unattainable or misguided; the reward promised is false.

A small amount of knowledge can mislead individuals into believing that they are more experienced and expert than what is actually the case.

Alternative form of the law is an ass

A promise that one makes should be or can be considered a promise that one will certainly honor.

Humans prey upon one another.

(idiomatic) In politics, a lot of change can happen in a short space of time.