REPETITION

Proof by repetition is sometimes referred to by its Latin name, « argumentum ad nauseam », meaning « to the point of nausea. »

In ordinary conversation, any meaningful or pragmatically relevant segment may be repeated for various reasons. For instance,a speaker may repeat something if it was not clearly heard or understood; a second speaker may repeat the end of the first speaker’s turn to connect it with their own.
Repetition may consist of reproducing a segment of speech word for word, as is the case in formal quotations. It may also be a slightly modified restatement of something ubiquitous, such as a familiar argument borrowed from an argumentative script. Deliberate, strategic repetition of slightly modified core content is key to traditional educational methods, and repetition of the same action is the basis of learning by doing, etc.

Persuasive repetition is characterized by the following elements.
– Invariance of the repeated formula.
– Frequency of these repetitions.
– They are produced as catchphrases by a social medium for political or commercial purposes.
– Their format excludes listener participation.
– The act of repetition can continue indefinitely.

While most repetition is unplanned and goes unnoticed, argument by repetition or proof by repeated assertion is part of a strategy used to impose a one-sided, uncritical view on people. The focus is on a single key claim, presented as a necessary truth. The specific function of repetition is to create a sense of a familiar self-evidence, beyond proof.

Although this process is called “argument (by repetition)”, it is characterized by the absence of argument. It offers no reasons, good or bad, to support the claim. Reasons are not implied or contextually retrievable, rather, they are carefully ignored.
Therefore, repetition can be considered argumentative only if an argument is defined by its persuasive effect; but persuasion is not a defining effect of argumentation
Repetition is instrumental to persuasion, which itself could be considered as a  willingness to repeat something under appropriate circumstances.
Repeating an entire complex argument results in an argument by repetition rather than any other kind of argument: “We will win because we are the strongest”.

Sociologist Gustave Le Bon emphasized the power of repetition to win people’s approval:

Pure and simple assertion [affirmation], kept free from all reasoning and all proof, is one of the surest means of getting an idea into the minds of crowds […]
Affirmation, however, has no real influence unless it is constantly repeated, and so far as possible in the same terms. It was Napoleon, I think, who said that there is only one figure in rhetoric of serious importance, and that is, repetition. By repetition, what is affirmed becomes so fixed in the mind in such a way that it is finally accepted as proven truth. […]
It is to this fact that we owe the amazing power of advertising. When we have read a hundred, or a thousand times that X’s chocolate is the best, we imagine that we have heard it said from many sides, and we finally acquire the certainty that it is a fact. (Le Bon [1895], p. 126-127)

This last remark shows that repetition can create an illusion of legitimacy through the authority of large numbers, see consensus.

From an evaluative standpoint this form of repetition is considered a fallacy, and even as the fallacy par excellence, since it imposes the acceptance of a statement not only without justification but against any justification.