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For questions about logic, whether it concerns syllogistic logic, mathematical logic or the nature of logic itself.

2 votes

Why must the sentence form of a valid argument be tautological?

There's nothing deeper going on here. An argument, "P proves Q" is valid iff it is true for all assignments P,Q iff P-> Q is a logical truth, also known as a tautology This does invoke soundness/comp …
3 votes

If P is a property, then is (not P) a property?

It depends on what objects you want to apply the property to. A property is formally defined as just a set, and so you'd think you can just take the compliment of the set defining P, and have the set …
3 votes

Is there a logical fallacy in "dropping down" to a different level of abstraction?

There are multiple options depending on how the anecdote is presented within the context of the argument. To take an example I recently came across, many autistic people like to be referred to like t …
3 votes

Is the use of inconsistent definitions a logical fallacy?

I wouldn't call this a logical fallacy, because the logical reasoning very well may be correct. A logical fallacy is when there is something wrong with the logical form of the argument, not its descri …