1. Argumentation

2. Aim of philosophical method: knowledge How do we get to knowledge?
Way 1: Socratic Dialectic: propose definitions until we reach an adequate definition
Way 2: Provide a good argument for the knowledge

3. statement Premise
statement Premise
Therefore, statement Conclusion
Conclusion = what we are attempting to show
Premises are reasons for the conclusion; true premises justify the conclusion
A good argument show what follows from our beliefs

4. Interpreting Ordinary Language
Telling a white lie is morally permissible. We should judge the rightness of an act by its impact on human well-being. If an act increases human well-being, then it is right. Without question, telling a white lie increases human well-being because it spares people’s feelings; that’s what white lies are for.
Argument
If an action is morally right then it increases human well-being
If an action spares people’s feelings, then it increases human wellbeing
Telling a white lie spares people’s feelings
Telling a white lie increases human well-being
Therefore, telling a white lie is morally right

5. Indicator Words
Indicating Conclusion: therefore, so, consequently, hence, it follows, thus, as a result
Indicating a Premise (reason): since, because, for, given that, assuming that

6. Kinds of Arguments Inductive Arguments Deductive Arguments
Abductive Arguments

7. Induction Example A pinch of salt dissolved in water at time t1
Another pinch of salt dissolved in water at time t2 ….
Another pinch of salt dissolved in water at time t100
Therefore, any pinch of salt will dissolve in water at t
The conclusion could be false given that the premises are true
Tnductive arguments establish only a probable conclusion; probably any pinch of salt will dissolve in water

8. Deductive Arguments All men are mortal Socrates is a man
Therefore, Socrates is mortal
Deductive arguments establish the conclusion necessarily (not just a probabilistically) given that the premises are true
The conclusion is necessarily true given premises are true

9. Deductive Argument
An deductive (valid) argument =df It is impossible for the conclusion to be false given that the premises are true; or to put it differently if the premises are true, the conclusion must necessarily be true.
An invalid argument =df an argument that is not valid.
A sound deductive argument =df a valid argument with true premises;
An unsound deductive argument =df an argument that is not sound.

10. Valid Argument Forms Modus Ponens: Modus Tollens If p then q P
Therefore, q
Modus Tollens
Not q
Therefore, Not p

11. Valid Argument Forms Hypothetical Syllogism Example If p then q
If q then r
Therefore, if p then r
Example
If capital punishment deters crime then the number of death row inmates will decrease over time
But, capital punishment does not deter crime
Therefore, the number of death row inmates will no decrease over time

12. Arguments Going Wrong valid but premises are not true
All humans are four-legged
All four-legged things are blue
So, all humans are blue
premises are true but invalid
Gainesville is in Florida
Gators are Gainesville’s football team
Therefore, Gators are National champions in 2007.
both invalid and premises not true

13. Invalid Argument Forms
Denying the Antecedent
If p then q
Not p
Therefore, not q

14. Evaluating Arguments Causing a person’s death is wrong
Individuals in a deep, irreversible coma are incapacitated persons
“Pulling the plug” on someone in a deep irreversible coma is causing a person to die
So, “pulling the plug” on someone in a deep, irreversible coma is wrong

15. Making Adjustments
Causing the death of a person who is incapacitated is wrong
Individuals in a deep, irreversible coma are person
Pulling the plug on someone in a deep, irreversible coma is causing an incapacitated person to die
So, “pulling the plug on someone in a deep irreversible coma is wrong”

16. Making Adjustments
Causing the death of a person who is incapacitated is wrong, except to save lives
Individuals in a deep, irreversible coma are persons
“Pulling the plug” on a deep, irreversible coma cause a person to die
So, ‘pulling the plug’ on a deep irreversible coma is wrong (except to save lives).

17. Abductive Arguments Also known as ‘inference to the best explanation’
Examples
Phenomenon p
If hypothesis h were true, it would provide the best explanation of p
So, it is probable that h is true.

18. Criteria for Abductive Arguments
A hypothesis is better than another if it is better in one of these three ways
Consistency: the hypothesis must not itself involve a contradiction
Conservatism: all else being equal, the better hypothesis is the one that fits what we already know
Simplicity: all else being equal, the better hypothesis is simpler; it makes fewer assumptions

19. My car makes noise when turning and skids and has worn tires.
Hypothesis 1: The worn tires are causing Joe’s car to skid and screech
Hypothesis 2: There was no skidding and screeching; I was hallucinating
Hypothesis 3: An omnipotent being is causing the screeching and skidding
Best explanation is Hypothesis 1: it’s simplest, most consistent with other evidence