Tautology is the useless repetition of words.

I am going to the mall or I am not going to the mall is a tautology.

Tautology is not simply the useless repetition of words. It is more about redundancy. The example above is tautology but it is because the phrase is redundant. "I may go go the mall today." implies that I may not to to the mall today. To include that I may not would be tautology.

Another example of tautology is when you have two words whose meaning is the same used in conjunction. "Free gift" and "unsolved mystery" are tautology. The words are synonymous and therefore they are redundant.

The person kept saying the same thing over and over which had no meaning so it was tautology.

THE TRUTH

a tautology

Wittengstin