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Summary of Week 3

Summary of how we know if an argument succeeds logically.

So what have we done this week?

We’ve introduced you to the principle of charity: to be charitable is to treat others as intelligent. This is most important if you don’t agree with someone’s view. You’ll do a much better job if you can show that the best version of their argument fails.

We’ve talked about the important distinction between deductive and non-deductive arguments. How do you choose whether an argument is deductive or non-deductive? Simple: unless the argument clearly indicates that it is deductive, apply the principle of charity and take it to be non-deductive.

We also learnt to decide when arguments succeed logically.

  • A deductive argument succeeds logically if it is valid: it is impossible for the premises to be true and the conclusion false.

  • A non-deductive argument succeeds logically if it is strong: it is improbable for the premises of the argument to be true and the conclusion false.

Of course, for an argument to succeed logically doesn’t mean that it’s a good argument. It’s all good to know that it’s impossible (or improbable) for the premises of the argument to be true while the conclusion is false, but are the premises actually true? This is the next stage in argument evaluation: once you know that argument succeeds logically, then you go ahead and ask if the premises are true. That’s what we’ll focus on next week.

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Logical and Critical Thinking

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