Unit 2 (Argument Evaluation) Flashcards
What are the reasons that we write in standard form?
- avoids extra steps and easier to see what is part of the argument
- spot missing premises
- easier to understand and evaluate
- simpler and more convenient as everything is numbered.
What are the two ways an argument can go wrong?
- conclusion does not follow from its premises
- premises that is not true
How is standard form supposed to be like?
Premises on their own line, numbered, and clearly stated. Conclusion on its own line and numbered.
How can we determine validity by playing pretend?
It is when we pretend the premises are true and ask ourselves then does the conclusion have to be true. If NOT then it’s invalid.
What is a valid argument?
If the premises are true, than conclusion HAS to be true.
What is a invalid argument?
not valid, it is possible for the premises to be true and the conclusion false
or the premises do not guarantee the truth of the conclusion.
What is the common pattern of valid arguments?
- If P, then Q.
- P.
- Therefore, Q.
What are the six valid argument forms?
- Argument by elimination
- Simplification
- Modus Ponens
- Modus Tollens
- Hypothetical Syllogism
- Equivalence
Argument by Elimination
- Either P or Q.
- Not P.
- Therefore, Q.
Simplification
- P and Q.
- Therefore, P.
Modus Ponens
- If P, then Q.
- P.
- Therefore, Q.
Modus Tollens
- If P, then Q.
- Not Q.
- Therefore, not P.
Hypothetical Syllogism
- If P, then Q.
- If Q, then R.
- Therefore, if P, then R.
Equivalence
- P if and only if Q.
- Not P.
- Therefore, not Q.
What are the two invalid argument forms?
- Affirming the consequent
- Denying the antecedent