The fallacy of argumentum ad nausem (or argumentum ad infinitum, or proof by repeated assertion) occurs when an arguer merely reiterates the same position over and over, with the aim of exhausting the ability (or the willingness) of the other side to engage in debate, whereupon the arguer declares victory in the argument.

The simplest examples are perhaps those of children quarreling, such as this:

Dora:"You stepped out of bounds. So, it's my ball now."

Lola: "No I didn't."

Dora: "Penny and Lena, did you see it? Was she out of bounds?"

Penna and Lena: "Yes."

Lola: "But I wasn't."

Dora: "How can you deny it?"

Lola: "Because I wasn't out. No way was I out. You can't say I was out when I wasn't. I was totally in. I am keeping the ball because I was not out of bounds. No way on earth was I out, not even a little. Not even close."

Dora: "Good grief. Have it your way, then."

Lola: "See! You admit that I was in!"

Lola has not really convinced anyone and has provided no valid argument for her conclusion. Instead, she has dragged out the dispute until no one else cares to discuss it any further.