"Rhetorical phrases can make an argument memorable..."

Example:

Rhetorical version

History always favors freedom.

It is memorable.

But how do we know it is true?

No evidence has been given.

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Argumentative version

Between 1789 and 1900, multiple legal reforms in different countries expanded contractual freedom in labor relations. Parliamentary debates, legislation, and economic records suggest these reforms coincided with the growth of wage labor and industrial production. Therefore, there is evidence that legally free labor became increasingly important in the development of industrial capitalism.

This version is less dramatic, but it gives readers reasons they can examine and challenge.

That is why rhetoric can strengthen presentation, but it cannot substitute for evidence and logical argument.