Who Defined the Study of

Philosophy and Logic?

• Socrates, Plato and Aristotle

• These three philosophers form the basis of

what is known as Western Philosophy

• Every thinker and scientist that followed

used their methods

Socratesb. 470 BCE

• Developed the Socratic method:• A series of questions are used to

examine beliefs and develop ideas.

• “The unexamined life is not worth living.”

• “ There is only one good, knowledge, and oneevil, ignorance.”

• “Know thyself.”

• Was executed in Athens after being convicted ofcorrupting the youth with his ideas.

Platob. 428 BCE

• Was Socrates’ brilliant student

• Traveled extensively before returning to teach atThe Academy.

• Allegory of the Cave- the real world is only areflection of the truth, of a higher reality

• He believed that the perfect political system wouldfeature “philosopher kings” as it rulers, peopleversed in ethics and who truly loved only onething: truth and knowledge

Aristotleb. 384 BCE

• Plato’s student

• Aristotle studied almost every single topic from

anatomy to economics to geography, physics,

politics, psychology, religion, and even poetry.

• He founded his own school after leaving the

Academy, and his center of knowledge became

known as the Lyceum.

• Was Alexander the Great’s personal teacher.

Aristotle Part 2

• Developed a vast system of rules for logicalthinking to define the world.

• Much like a game has rules, so, too, must logic

• Syllogism def. If A=B and B=C, then A=C

• Causality: If I set fire to a piece of paper (cause)then it will burn (effect).

• Scientific Method:• 1. Observe and take notes

• 2. Make a theory

• 3. Test the theory

What is Logic?• Def. logic is the study of the rules for correct, or valid,

reasoning.

• Deduction: Reasoning that moves from the general to the specific. It is

a form of inference where if the premises are true, the conclusion must

also be true.

– All humans have two legs, the major premise,

– I am a human, the minor premise, therefore,

– I have two legs, the conclusion.

• Induction: Reasoning that typically moves from specific examples to a

larger, general observation. If the premises are true, it is improbable that

the conclusion is false.

– '95 households out of 100 have a TV. I am going to stay

with Fred, so I will probably be able to watch TV".

Quick check: Stop taking notes!

• I failed that course because the instructor didn’t like me.

Assumption: The instructor fails students he doesn’t like.

• I’m not surprised he made the team. After all, his father is thesuperintendent of schools.

Assumption: The superintendent gives special favors to his family

• If I’d only taken my boss to lunch more often, I could have gotten thatraise.

Assumption: The boss denies raises to people who don’t take him tolunch very often.

Analyze the assumptions behind every idea!!!

What are the unstated assumptions?What is a syllogism?

• a specific method of logical deduction(moving from the general to the particular)

every syllogism contains at least three parts:

– a major premise (global assumption)

– a minor premise (specific claim)

– a conclusion

• It’s kind of like simple math

If A = B and B = C, then A = C

A visual representation

all things with hairall mammals have hair

mammalsfish do not have hair

fish

Fish are not mammals

Not in your notes -- just think it through!

True vs. Valid Arguments

• True argument = an argument with a conclusion

that is considered factually correct.

• Valid argument = an argument with a

conclusion that makes sense logically, regardless

of whether it is true or not.

Recognizing Logical Fallacies

A logical fallacy is a mistake inreasoning; it is a MENTAL TRAP

Looking at the Negative Space

• We can learn much

about logic by studying

that which is not

logical—examples of

where logic breaks

down, logical fallacies.

1. Over-generalization

• Drawing too wide a conclusion from thegiven facts

• Example:– All kids cause trouble.– Timmy is a kid.– Therefore, Timmy causes trouble.

Fix this by recognizing qualifiers

(many, few, some, all, etc.)

2. Arguing in Circles• Def: Supporting an opinion not with evidence but with the same

opinion, slightly disguised (restating the argument in differentwords). Using the word you’re defining in the definition is a classicexample.

• Example:– Education is important for kids, so they should get an education.– Everybody likes ice cream because it is liked by all.– “Belligerently” means in a belligerent way.

Fix it by making sure you are giving support, not justrepeating the idea. Never use the word you’re

defining in the definition.

3. Black & White Thinking

• Def. An opinion that claims there are onlytwo alternatives (when there might be more)

• Examples:

– You’re either for it or against it.

– Are you a jock or a nerd?

Fix this by remembering that the world is acomplicated place and that on most issues

there are many alternatives.

4. Red Herring• Def. Presenting an irrelevant topic to divert

attention away from the original issue.

• Also known as Ad hominem: getting

personal as you discredit someone.

• Examples:

– What do you know? You’re just a kid.

– I got an F. Mr. X hates me.

Fix this by staying focused on the topic;

watch out for those who don’t.

5. Loaded Questions and

Statements

• Def. A question or a statement thatconceals an opinion or assumption.

• Examples:

– Do you still beat your dog?

– You don’t think that, do you?

– All intelligent people agree that …

Fix this by listening carefully andseparating fact from opinion.

6. Statistical Fallacies

& False Authority• Def. People usually believe in numbers and experts without

questioning them. Here statistics are used to misrepresent

rather than describe.• Examples:

– 3 out of 4 dentists prefer Crest. (Did Crest pick the dentists?)

– I surveyed 100 people and they all agreed with me. (I chose my friends).

– Dr. X says this is the fastest and safest way to lose weight. (Did he/she get paid?

Where do they practice?)

Fix this by analyzing the evidence. Where did the support come from? Is there

self interest involved? Did you get the whole picture?

7. Faulty Causal Relationship

(also called Post Hoc)

• Def. To excuse an action or belief by making it sound sensible.

Often this assumes that anything that came before an event caused

it to happen.

• Example:

– I stole the towel from the hotel. They expect people to take them.

– Eating 5 energy bars and drinking 2 Cokes helps me get better grades. I did

this and got an A on my history test.

Fix this by examining the relationship between ideas. Make sure the

facts precede the theory and the reasons precede and cause the

belief.

8. Misleading Comparison

• Def. Mistakenly believing that two

situations or people can be compared.

• Examples:

– Jill looks good in red. I’ll buy red pants, too.

– Forcing students to read books is like herding

cattle to slaughter.

– You gave him extra time on the test, so I should

get extra time too.

– Saddam Hussien is Hitler.

Fix this by remembering that every person

and situation has different circumstances.

9. Bandwagon

• Def. Lots of people do this, so you should,

too.

• Examples:

– Adults are smoking, so it is ok to do so.

– The American people do not stand for . . .

Fix this by making decisions based on facts,

not popularity.