Philosophy 102 how to read philosophy

Logic and critical thinking is the field that studies reasoning, specifically, how to distinguish good reasoning from bad

1. It enables us to learn more about our own language (ambiguity of different words and phrases)
2. It helps people reason better (learning the difference between good, bad and fallacious reasoning) in our everyday lives

A premise and a conclusion

A reason that provides support or evidence for a conclusion. Can come before or after the conclusion. Is not always implicit. There can be multiple premises linked together on the way to the conclusion
"Because", "for the reason", "since" but are not always used

A statement for which reasons are given. Sometimes is not stated
"hence", "therefore", "it follows that", "in conclusion"

Are always either weak or strong
While it is always possible that the conclusion is wrong, focuses more on the strength of the argument and the degree in which the premises justify the conclusion

Is either valid or invalid
If the premises are true then the conclusion must be true
If valid can be sound or unsound

1. Generalization
very few As are also B
x is an A
x is probably not B
2. Predictions
In the past when I have done Y followed X
If I do X now, Y will likely follow
3. Casual references
People in this area often have characteristic C
People in this area have been exposed to D a lot
Exposure to D causes C
4. Analogies
Everything I have examined with characteristics A, B, C, D, and E is also a Q
t has characteristics A, B, C, D, and E
So t is also probably Q

A higher level of induction uses refined judgement about an individual case when a generalization is used for example

Mistakes we typically make in reasoning

"To the person/man". Instead of attacking a person's position or argument, the arguer attacks the person on irrelevant grounds

Because something has not been proven true, it must be false (and vice versa)

The argue appeals to the popularity of an idea or of an attitude as a justification
The bandwagon effect

The premise, that somebody is powerful, does not warrant that the person/belief is correct

The arguer attacks a weaker argument/position (may be on purpose or because they misinterpreted the argument) that is not one their opponent is defending

Reaching conclusions based on small samples or stereotypes
One counter-example can serve as a refutation

Assuming that things will be the same or change because the future can be predicted from the past
"My number has got to come up soon!"
"If I bet more eventually I must win!"

Doing something that you won't enjoy because you already paid for it or put work into it, etc.

Asserting that two objects, situations, or events are similar in certain aspects so therefore they must share a further characteristic when in fact they are not alike in relevant ways or that their similarity does not mean that they share the further characteristic

Holding onto a premise or conclusion in one context that is incompatible with ones accepted in a different context
Mistaken premises

An argument depending on the author's equivocation between two different senses or meanings of a word or phrase which makes the key premise false

Circular reasoning
Instead of giving a reason that establishes the conclusion, the conclusion is simply assumed
The conclusion is also a premise and there is no good reason to accept the conclusion

If one takes a first step or two, then inevitably they will be led down a slippery slope to someplace they don't want to go, despite the lack of justification from the author

The arguer unreasonably reduces the alternatives by arguing that there are only two possibilities when there actually are others

The arguer diverts attention away from the real issues onto an irrelevant side issue, ignoring the opponent's argument altogether

It is often controversial whether or not a fallacy is really present

The correctness of formal fallacies is determined by the argument alone
Informal fallacies depend of specific content or meaning of premises and conclusion, etc.

The premises (if true) establish the conclusion with certainty
It is impossible for the premises to be true and the conclusion false

If the argument is valid and all of the premises are true
It is unsound if at least one premise is false

Express the relations among classes or groups of things
1. Form A: All As are Bs
2. Form E: No As are Bs
3. Form I: Some A is a B
4. Form O: Some A are not a B

Quality and Quantity
Quality asks whether or not the statement affirms or negates class membership
Quality asks whether or not the statement says something about every member of the subject class

A form is universal affirmative
E is universal negative
I is particular affirmative
O is particular negative

1. Contradiction
2. Contraries
3. Subcontraries
4. subalterns

If each of them have the opposite "truth value"

When both statements cannot be true but can be anything else

When both statements cannot both be false but can be anything else

When one statement being true requires that the second is true while the second's statement being false means the first must be false

The traditional square of opposition

"Non-A" refers to the complement fo the class of As

Switching the subject and predicate terms so the converse of "all A is B" is "All B is A"

Quality and Quantity
Quality asks whether or not the statement affirms or negates class membership
Quality asks whether or not the statement says something about every member of the subject class

A form is universal affirmative
E is universal negative
I is particular affirmative
O is particular negative

1. Contradiction
2. Contraries
3. Subcontraries
4. subalterns

If each of them have the opposite "truth value"

When both statements cannot be true but can be anything else

When both statements cannot both be false but can be anything else

When one statement being true requires that the second is true while the second's statement being false means the first must be false

The traditional square of opposition

"Non-A" refers to the complement fo the class of As

Switching the subject and predicate terms so the converse of "all A is B" is "All B is A"

Combining conversion and complements
"All A is B" has its contrapositive "All non-B is non-A"

Reverse the quality and substitute the compliment for the 2nd class
"All A is B" = "No A is non-B"

Does not assert either option but instead at least one or the other is true
Premise 1: Either P or Q
Premise 2: Not Q
Conclusion: P

If one thing happens or is, another thing will happen or is
"If P then Q"

Premise 1: If P than Q
Premise 2: P
Conclusion: Q

Premise 1: If P than Q
Premise 2: Not Q
Conclusion: Not P