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
Affirming the consequent
- If P, then Q.
- Q.
- Therefore, P.
Denying the antecedent
- If P, then Q.
- Not P.
- Therefore, not Q.
What are the two kinds of validity?
semantic and modal
Semantic Validity
valid because it follows a valid form
Modal Validity
valid because of the meaning of the terms
True or false: Valid argument can have false premises.
True
What are the steps of argument evaluation?
- Determine if the argument is valid
- Evaluate arguments premises
Step 1 of argument evaluation: Determine if the argument is valid
Does the conclusion follow from the premises.
Step 2 of argument evaluation: Evaluate arguments premises
- Are the premises true? Sound arguments
- Are the premises reasonable to believe? Strong arguments
- Are the premises known? Known arguments
Ways an argument can be GOOD
- Sound arguments
- Strong arguments
- Known arguments
Sound arguments and its limitations
- valid with true premises
- Limitations: don’t always have access to the truth and can have premises not supported by evidence
- Even if an arguemnt is sound we still have no reasons to believe its conclusion
Strong and its limitations
- Valid with premises that are reasonable/rational to believe
- strength of the argument can vary from person to person and can vary for a single person over time
- Limitations: can have premises and conclusions that are false
For strong arguments does the number of premises matter?
- the number of premises matters as too many will result into stuff like the lottery paradox
- To avoid the paradox it is reasonable to believe all the premises together
Known Arguments
- valid with premises known to be true and reasonable to believe * basically sound AND strong*
- best kind of argument
To know a premise is true:
You need to believe it and luck cannot be involved.
Problem with Known Arguments
Knowledge is a high bar
Strong arguments and sound arguments: which is subjectively good and which is objectively good
Strong = subjectively good
Sound = objectively good
What arguments give us reason to believe their conclusion?
Known and strong
What argument is both subjectively and objectively good?
Known argument
Which argument can have false premise?
Strong premise
