In epistemology, the Münchhausen trilemma, also commonly known as the Agrippan trilemma, is a thought experiment intended to demonstrate the theoretical impossibility of proving any truth, even in the fields of logic and mathematics, without appealing to accepted assumptions.If it is asked how any given proposition is known to be true, proof may be provided.

The Roman numeral M represents the number 1000, though it was not used in Roman times.There is, however, scant evidence that the letter was later introduced in the early centuries A.D. by the Romans. Unit prefix M (mega), meaning one million times, and m (milli) meaning one-thousandth.; m is the standard abbreviation for metre (or meter) in the International System of Units (SI).