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Skip to 0 minutes and 15 secondsBy the end of the week, you'll be able to evaluate arguments as good or bad using this diagram, but don't worry, the next video will explain how to read it. Before watching it, you need to acquire some more skills. One important skill is to be able to create counter examples to show that arguments fail logically. A counter example is in principle easy to understand, but it's a lot harder to be able to create them. For that, you need a lot of practise, and we have a lot of exercises to help you learn it. If you can come up with a counter example to an argument, then you know immediately that the argument is bad, because it fails logically.

Skip to 0 minutes and 56 secondsIf you can't create a counter example, then you need to inspect the truth of the premises. It's at that point that you start considering what the premises are about, if they make sense and whether they are true. If you can satisfy yourself that the premises are true, perhaps because they are backed up by good sub-arguments, then you know that you have a good argument. If a premise is false or if it's not backed up by a good sub-argument, then the argument is bad. There are further complications that involve irrelevant premises, but we'll show you how to identify and cope with them. To get your hands dirty with arguments, I would like you to evaluate a bunch of them.

Skip to 1 minute and 36 secondsTo be good at it, you need a lot of practise, but once you get the hang of it, you'll be a kick ass critical thinker.

Good and bad reasoning

An argument is good if it succeeds logically (that’s what we learnt last week) and if the premises are true. Otherwise, it’s bad.

By the end of the week, you will be able to evaluate arguments as being good or bad. In particular, we will help you to:

  • Create and use counter examples to show that arguments are invalid or weak.

  • Identify irrelevant premises.

  • Distinguish between sound and cogent arguments.

  • Evaluate arguments as being good or bad.

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This video is from the free online course:

Logical and Critical Thinking

The University of Auckland

Get a taste of this course

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