Incomplete truth, without context
In philosophy, a sentence which asserts incomplete truth conditions for a proposition may be regarded as a truism. An example of such a sentence would be: “Under appropriate conditions, the sun rises.” Without contextual support — a statement of what those appropriate conditions are — the sentence is true but incontestable. A statement which is true by definition (“All cats are mammals.”) would also be considered a truism. This is quite similar to a tautology in which the conclusion of a statement is essentially equivalent to its premise, a statement that is “true by virtue of its logical form alone”.