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Logic and arguments

The first step in evaluating arguments is to make sure they succeed logically.
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Last week, you learned the basics of critical thinking. The fundamental concept is that of an argument. You can now identify arguments in the wild, and you can put them in standard form. This is the first step in the evaluation of arguments. In the next two weeks, we will start evaluating arguments properly. Crudely, this week is about the logical aspect of arguments and next week about the content. That’s because there are two ways in which arguments can fail. Either by having a bad logical structure or by having false premises. And it’s very important to be able to separate the two.
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This week because we are doing logic, it’s important for you to be able to extract from the content of the premises. Arguments can be logical even though the statements that form them are entirely rubbish. Logic is not about the content of sentences. It’s about how they are related together. Remember that premises are there to provide support for the conclusion. Well, logic is about investigating whether or not the support is adequate, irrespective of the truth of the premises. You only inspect the truth of the premises once you know that the logic is adequate. If the logic is not adequate, it doesn’t matter what the premises are about. They won’t provide adequate support for the conclusion.
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This will be our topic this week, whether arguments have adequate logic. More specifically this week, you need to learn the important difference between deductive and non-deductive arguments. And then learn how each kind of argument can succeed logically. Deductive arguments succeed logically when they are valid. And non-deductive arguments succeed logically when they are strong. You also need to learn about the principle of charity and learn how to apply it when you’re evaluating arguments. To be charitable is to treat others as intelligent persons and take the best form of their arguments. Failure to be charitable is the source of critical and logical mistakes that are very common.
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Learning to be charitable gets you a long way to becoming a good logical and critical thinker. This week, I’m talking to John Bishop about the importance of the distinction between deductive and non-deductive arguments as it plays out in the philosophy of religion. You should first read the article on deductive and non-deductive arguments before you watch the interview.

In arguments, premises are offered to provide support for the conclusion. Logic is about whether or not the support is adequate. If the logic is not adequate, it doesn’t matter what the premises are about; they won’t provide adequate support for the conclusion. The first step in evaluating arguments is thus to make sure they succeed logically.

More specifically, you need to learn the important difference between deductive and non-deductive arguments. And then learn how each kind of argument can succeed logically.

This week, we aim to help you to:

  • Distinguish between deductive and non-deductive arguments.

  • Distinguish between valid and invalid deductive arguments.

  • Distinguish between strong and weak non-deductive arguments.

  • Apply the principle of charity in reconstructing arguments.

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Logical and Critical Thinking

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