Do extraordinary claims require extraordinary evidence? Is there a burden of proof against extraordinary claims? Should we literally assume that something extraordinary doesn’t exist until it is proven to exist?
Many people say that those who claim that bigfoot, ghosts, and gods exist are making “extraordinary claims” and we should reject the existence of these things because we don’t have enough evidence for them.
What does ‘extraordinary’ mean? It refers to claims that conflict with what we think we know about the world. Many claims are extraordinary because they are extreme (likely false) or potentially impossible. (more…)
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This is part 6 of a series. Links to the other parts of the series are above.
The straightforward way to construct proofs using natural deduction is called the “direct method.” Every line of that type of proof is validly deduced from the premises and rules of inference. Every line of such a proof could be considered to be true as long as we consider the premises to be true. However, there are two other strategies: The conditional proof and the indirect proof. Both of these types of proofs introduce an additional premise that is assumed to be true “for the sake of argument.” (more…)
Part 1 | Part 2 | Part 3 | Part 4
This is part 5 in a series. There are links to the other parts of the series above.
Natural deduction is used to give proofs of validity by showing all the steps in reasoning required. In this case natural deduction uses rules of inference to allow us to reach conclusions from statements of propositional logic. (more…)
At some point you are likely to hear about how giving arguments is rude and we would all get along better without arguing. Arguing is often thought to be a shouting match or hostile disagreement of some sort. However, argumentation is central to thinking rationally and critical thinking. The success of natural science could not exist without it. Yes, some arguments are disrespectful, but not all of them are. (more…)