Rules for writers, Tenth edition - Diana Hacker, Nancy Sommers 2021

Identify underlying assumptions
Reading arguments
Academic Reading and Writing

An assumption is a claim that is taken to be true without the need for proof. As you read and evaluate an argument, identify the underlying assumptions on which the argument is based. Look closely at the ideas, values, and beliefs the writer assumes they share with their readers to determine whether those assumptions need to be stated and supported rather than merely accepted as true.

Writers often assume that they share values and beliefs with readers and don’t make their assumptions explicit. For example, if you read an argument about limiting population growth in developing nations and the writer assumes that readers agree with this goal, you might want to question the assumption by asking, “What evidence shows that limiting population growth is always desirable?” Or if a writer argues that everyone agrees that violent crime is increasing because the death penalty isn’t widely used, you might want to question the writer’s assumptions by asking, “What evidence shows that the death penalty deters violent criminals and that it is a fair punishment?” Perhaps the unstated assumptions are the ones that the writer needs to state as claims and support with evidence.