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Question: Introduction to Logic!?
For each of the following: Is it a tautology, a contradiction, or a contingent
1!. Caesar crossed the Rubicon!.
2!. Someone once crossed the Rubicon!.
3!. No one has ever crossed the Rubicon!.
4!. If Caesar crossed the Rubicon, then someone has!.
5!. Even though Caesar crossed the Rubicon, no one has ever crossed the
6!. If anyone has ever crossed the Rubicon, it was CaesarWww@QuestionHome@Com

Best Answer - Chosen by Asker:
1!. Contingent sentence
2!.Contingent sentence
3!.Contingent sentence
6!.Contingent sentence

A tautology is of the form p=p, so #4 is one because it is basically {someone crossed, therefore someone crossed}

A contradiction is of the form P= not P, so #5 is one because it is basically {someone crossed and someone didn't cross}

A contingent sentence is one that can be either true or false depending on what the terms in the sentence reference in the real world!. So let's take #1; If someone named Caesar did in fact cross the Rubicon, then it is true; otherwise it is false!.

However, if Caesar and the Rubicon mean something else then what they do in our world, those sentences could be contingent as well!. But I'm guessing the instructor wants those two answers to be as I put them!. {like if Caesar was the name of a rock}Www@QuestionHome@Com

Logic is relativeWww@QuestionHome@Com