Critical Thinking with Argument Maps

By Dave Kinkead, University of Queensland Critical Thinking Project

Identifying assumptions

Many of the arguments we hear, read, or make ourselves rely on unstated or implicit premises and assumed truths.

Sometimes, it is reasonable to not make these explicit. This would be the case when they are uncontested, very widely accepted, or self evident.

Other times however, these unstated premises are highly problematic. They are crucial premises that arguments rely upon and are the crux of the debate.

So when we are analysing arguments, it is important to bring these unstated claims into the open and submit them to scrutiny.

One effective way to do this is to ask the following questions:

What unstated premise is this inference relying on?
What additional premise would make the inference much stronger?

Consider our abortion argument so far … what premises are missing to make the inferences stronger?

In, we can indicate an assumption with a dashed line. So on the maps above, add any assumptions you think the argument is relying on.

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