Arguements

Question 1

Assuming that the premises are true is it possible for the conclusion to be false? If it is then the argument is invalid.

Answer 1

Test for validity

Question 2

Assuming the premises are true, what degree of probability would they confer upon the conclusion

Answer 2

Test for probability

Question 3

If P then Q
P
Therefore Q

Answer 3

Modus ponens (valid)
Affirming the antecedent

Question 4

If P then Q
Not P
Therefore not Q

Answer 4

Denying the antecedent (invalid)

Question 5

If P then Q
Not Q
Therefore not P

Answer 5

Modus Tollens (valid)
Denying the consequent

Question 6

If P then Q
Q
Therefore P

Answer 6

Affirming the consequent (invalid)

Question 7

In this form we have a conclusion that puts together information found in the premises.

Answer 7

syllogism

Question 8

Arguing for the truth based upon what is generally true.

Answer 8

Statistical syllogism
Example: Only about 2% of high school students take philosophy. Tom is a high school student, so he doesn’t take philosophy.

Question 9

An argument involving polling a sample group and arguing that what is true of the sample group is true of the population as a whole.

Answer 9

Statistical generalisation
Example: 9 out of 10 Owners said their cats preferred wild mice to birds. Woof is a cat, so he will prefer wild mice to birds.

Question 10

Relying upon the knowledge or testimony of others when something is beyond our experience and expertise.

Answer 10

Argument from authority
Example: I’m not going to eat red meat any more. My doctor said it eventually clogs the arteries and will lead to premature heart disease.

Question 11

When we believe that there are enough similarities between two things and that what can be said of one can be said of another.

Answer 11

Argument from analogy

Example: Stealing from your employer is wrong; it’s just the same as stealing from a shop.

Question 12

Inference to the best explanation, is a method of reasoning in which one chooses the hypothesis which would, if true, best explain the relevant evidence. Abductive reasoning starts from a set of accepted facts and infers to their most likely, or best, explanations.

Answer 12

Abduction
Example: the sun appears to move across the sky. The best explanation we have for this is that the earth must rotate. Therefore, the earth rotates.

Question 13

If P then Q
If Q then R
Therefore
If P then R

Answer 13

Hypothetical syllogism (valid)

Question 14

Either P or Q
If P then R
If Q then S
Therefore
Either R or S

Answer 14

Dilemma (valid)

Question 15

Either P or Q
If P then R
If Q then R
Therefore
R

Answer 15

Simplified Dilemma (valid)

Question 16

Either P or Q
It is not the case that P
Therefore
Q

Answer 16

Disjunctive syllogism (valid)