Deductive Arguments and Fallacies Review

Flashcards covering equivocation fallacies, soundness, validity, enthymemes, and counterexamples from lecture notes.

What is an equivocation fallacy?

It is an error in thinking where the same word is used multiple times in an argument, but its meaning changes each time, making the argument logically flawed.

What does it mean for an argument to be 'valid'?

An argument is valid if its conclusion must be true, assuming all of its starting statements (premises) are true, focusing on the argument's structure.

When is an argument considered 'sound'?

An argument is sound if it is valid AND all of its starting statements (premises) are actually true.

What makes an argument 'unsound'?

An argument is unsound if it is either not valid, or has at least one false premise, or both.

What is the consequence if an argument is sound?

If an argument is sound, its conclusion has to be true because its structure is good (valid) and its starting statements are all true.

What are the two main questions to ask when evaluating a deductive argument?

1) Does the conclusion have to follow from the starting statements (is it valid)? 2) Are the starting statements (premises) actually true?

Why is validity crucial for an argument?

To prove something absolutely true using logic, an argument needs to be sound, and for an argument to be sound, it must be valid. It also forces us to state hidden assumptions.

What is an 'enthymeme'?

An enthymeme is an argument where some of the starting statements (premises) are not directly said but are assumed to be true.

Why is it important to make the missing premises of an enthymeme clear?

It helps to check if the argument is logically sound and ensures we don't accidentally rely on hidden ideas that might not be true.

What is a 'bridging premise'?

A bridging premise is a missing starting statement that is added to an enthymeme to make it logically complete and valid.

How can you prove an argument is invalid?

The best way to prove an argument is invalid is to come up with a counterexample, which is a made-up situation where all the starting statements (premises) are true, but the conclusion is clearly false.

What is a 'counterexample' in the context of logical arguments?

A counterexample is a made-up situation where an argument's starting statements are true, but its conclusion is false, thus showing the argument is invalid.

Can you prove an argument is valid by thinking of one case where it seems to work?

No, you cannot prove an argument is valid by thinking of just one case where it seems to work; you need to show that the argument's general logical design guarantees the conclusion's truth.

What are 'hidden assumptions'?

Hidden assumptions are the starting ideas or beliefs that an argument relies on but doesn't clearly state, which are important to make clear for proper evaluation.

If an argument states 'Scottie Barnes is a Toronto Raptor. Therefore, Scottie Barnes will not make the NBA playoffs next year,' what bridging premise makes it valid?

The missing premise is 'All Toronto Raptors will not make the NBA playoffs next year.'

Provide a counterexample for the argument: (P1) A car won't start if it's out of gas. (P2) My car isn't starting. (C) So, my car is out of gas.

A counterexample would be if the car isn't starting because its battery is dead, not because it ran out of gas. In this case, P1 is true, but C is false.

What is the main point of making hidden beliefs explicit when evaluating an argument?

When we insist on making an argument valid, it forces us to clearly state all the assumptions we've been using without even knowing it, allowing us to question them.