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Another reason to focus on validity: unpacking your commitments

In this step we look at how we can use valid arguments to think about how our beliefs interact.
A laptop showing an image from the film The Matrix
© University of York

A further reason to look closely at validity picks up from the first reason: focusing on valid arguments will be particularly helpful in sorting out what to believe. This is because valid arguments unpack commitments. Let’s look at this idea.

Suppose I find I’m inclined to believe a bunch of claims about some particular topic, and I find there’s a valid argument from them to a conclusion that hasn’t struck me before. It seems then that, unless things change, I’m obliged to believe the conclusion (after all, if those claims I believe are true, then the conclusion will have to be true too).

There’s a couple of ways things could go here. In some cases, I might be entirely happy to sign up to the conclusion. If things are like this, no problem — I just add the conclusion to my (explicit) beliefs. In other cases, however, I might not feel happy to accept the conclusion. Here I’m faced with a clear choice (if the argument is valid): either, stop believing at least one of the premises, or suck it up and accept the conclusion after all. A lot of puzzles in philosophy get going like this. Here’s an example. (You might want to pause for a hot drink and a biscuit at this point.)

  • If I know I am eating a chocolate biscuit right now, then I know I am not in The Matrix.
  • I do not know I am not in The Matrix.
  • Therefore, I do not know I am eating a chocolate biscuit right now.

(Just in case you don’t know the film The Matrix, the basic idea is that people are hooked up to a machine which gives them experiences so it seems to them that they are moving through a real physical world and doing things when they are not. When we say ‘in The Matrix’ here, we mean ‘in the situation people were meant to be in in The Matrix’.)

What do you think is the most important reason we should look carefully at validity? Share your thoughts in Comments. (You might have thought of more possible reasons than the three we’ve noted. If you have, tell us about them.)

© University of York
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Logic: The Language of Truth

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