What is the act of providing support that strengthens an argument called?

The act of providing support that strengthens an argument is best termed 'evidence.' Evidence consists of facts, statistics, examples, or quotes from credible sources that serve to substantiate a claim or assertion made in an argument. It plays a crucial role in persuasive writing and speaking because it allows the author or speaker to present a logical basis for their viewpoint, thereby making the argument more convincing. In essence, evidence backs up claims with tangible support that can be examined and verified.

Other terms commonly confused in this context, such as 'backing,' refer specifically to additional support that strengthens a warrant or rationale in an argument, rather than the direct evidence itself. 'Clarification' involves making something clearer or simpler, which doesn't necessarily provide support to strengthen arguments. Similarly, 'explanation' involves providing reasons or context to help someone understand a concept or argument, but it doesn't inherently involve presenting supportive facts or data. Hence, while these terms relate to argumentation, 'evidence' is the most accurate term for the type of support that directly fortifies an argument.