In mathematical logic, a tautology is a formula or assertion that is true in every possible interpretation. An example is "x=y or x≠y". Similarly, "either the ball is green, or the ball is not green" is always true, regardless of the colour of the ball.

What does it mean when something is tautological?

1a : needless repetition of an idea, statement, or word Rhetorical repetition, tautology ('always and for ever'), banal metaphor, and short paragraphs are part of the jargon.— Philip Howard. b : an instance of such repetition The phrase "a beginner who has just started" is a tautology.

What is a tautological argument?

A tautological argument is otherwise known as a circular argument, that is, one that begins by assuming the very thing that is meant to be proven by the argument itself. ... This appears to be a legitimate argument, but if we take it apart, there is not much substance there.