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The Is-Ought Problem

If we're to have a valid deductive argument with a moral conclusion, there must be at least one moral statement in the premise.

David Hume claimed that you can’t derive an ‘ought’ conclusion from entirely factual or ‘is’ premises. Why not? Well, here’s an example:

  1. humans die if you electrocute them (Descriptive).
  2. Tim is human. (Descriptive). Therefore,
  3. you ought not electrocute Tim. (Moral).

That looks like a valid deductive argument, but notice that premises one and two do not entail the conclusion, three. Suppose you’re an executioner somewhere that uses the electric chair and that Tim has been properly convicted of a ghastly capital offence. You might agree with premises one and two. After all, that’s why you use the electric chair. And you wouldn’t be making a logical error if you denied the conclusion.

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Logical and Critical Thinking

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