Socrates, Plato, and Aristotle are considered the founders of Western philosophy. Socrates developed the Socratic method of questioning beliefs and examining ideas. Plato was Socrates' student and founded The Academy. Aristotle was both Plato's student and the tutor of Alexander the Great. He made significant contributions to logic and established the basis of scientific reasoning. Aristotle defined logic as the study of correct reasoning and developed formal rules for deduction and induction. Syllogisms and the scientific method are two logical systems developed by Aristotle.

1. Who Defined the Study of Socrates
Philosophy and Logic? b. 470 BCE
• Socrates, Plato and Aristotle • Developed the Socratic method:
• A series of questions are used to
• These three philosophers form the basis of examine beliefs and develop ideas.
what is known as Western Philosophy • “The unexamined life is not worth living.”
• Every thinker and scientist that followed • “ There is only one good, knowledge, and one
evil, ignorance.”
used their methods
• “Know thyself.”
• Was executed in Athens after being convicted of
corrupting the youth with his ideas.
Plato Aristotle
b. 428 BCE b. 384 BCE
• Was Socrates’ brilliant student • Plato’s student
• Traveled extensively before returning to teach at • Aristotle studied almost every single topic from
The Academy. anatomy to economics to geography, physics,
• Allegory of the Cave- the real world is only a politics, psychology, religion, and even poetry.
reflection of the truth, of a higher reality
• He founded his own school after leaving the
• He believed that the perfect political system would Academy, and his center of knowledge became
feature “philosopher kings” as it rulers, people
known as the Lyceum.
versed in ethics and who truly loved only one
thing: truth and knowledge • Was Alexander the Great’s personal teacher.

2. What is Logic?
Aristotle Part 2 • Def. logic is the study of the rules for correct, or valid,
reasoning.
• Developed a vast system of rules for logical
• Deduction: Reasoning that moves from the general to the specific. It is
thinking to define the world. a form of inference where if the premises are true, the conclusion must
• Much like a game has rules, so, too, must logic also be true.
– All humans have two legs, the major premise,
• Syllogism def. If A=B and B=C, then A=C
– I am a human, the minor premise, therefore,
• Causality: If I set fire to a piece of paper (cause) – I have two legs, the conclusion.
then it will burn (effect).
• Scientific Method: • Induction: Reasoning that typically moves from specific examples to a
• 1. Observe and take notes larger, general observation. If the premises are true, it is improbable that
the conclusion is false.
• 2. Make a theory
• 3. Test the theory – '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!
What are the unstated assumptions?
What is a syllogism?
• I failed that course because the instructor didn’t like me. • a specific method of logical deduction
Assumption: The instructor fails students he doesn’t like.
(moving from the general to the particular)
• I’m not surprised he made the team. After all, his father is the
superintendent of schools.
Assumption: The superintendent gives special favors to his family every syllogism contains at least three parts:
• If I’d only taken my boss to lunch more often, I could have gotten that
raise. – a major premise (global assumption)
Assumption: The boss denies raises to people who don’t take him to – a minor premise (specific claim)
lunch very often.
– a conclusion
Analyze the assumptions behind every idea!!!
• It’s kind of like simple math
If A = B and B = C, then A = C

3. Not in your notes -- just think it through!
A visual representation True vs. Valid Arguments
all things with hair
all mammals have hair
• True argument = an argument with a conclusion
that is considered factually correct.
mammals
fish do not have hair
• Valid argument = an argument with a
conclusion that makes sense logically, regardless
of whether it is true or not.
fish
Fish are not mammals
Looking at the Negative Space
Recognizing Logical Fallacies
• We can learn much
about logic by studying
that which is not
A logical fallacy is a mistake in logical—examples of
reasoning; it is a MENTAL TRAP where logic breaks
down, logical fallacies.

4. 1. Over-generalization 2. Arguing in Circles
• Def: Supporting an opinion not with evidence but with the same
• Drawing too wide a conclusion from the opinion, slightly disguised (restating the argument in different
words). Using the word you’re defining in the definition is a classic
given facts example.
• Example: • Example:
– Education is important for kids, so they should get an education.
– All kids cause trouble.
– Everybody likes ice cream because it is liked by all.
– Timmy is a kid. – “Belligerently” means in a belligerent way.
– Therefore, Timmy causes trouble.
Fix it by making sure you are giving support, not just
Fix this by recognizing qualifiers repeating the idea. Never use the word you’re
defining in the definition.
(many, few, some, all, etc.)
3. Black & White Thinking 4. Red Herring
• Def. Presenting an irrelevant topic to divert
• Def. An opinion that claims there are only attention away from the original issue.
two alternatives (when there might be more)
• Also known as Ad hominem: getting
• Examples: personal as you discredit someone.
– You’re either for it or against it.
• Examples:
– Are you a jock or a nerd?
– What do you know? You’re just a kid.
Fix this by remembering that the world is a
complicated place and that on most issues – I got an F. Mr. X hates me.
there are many alternatives.
Fix this by staying focused on the topic;
watch out for those who don’t.

5. 5. Loaded Questions and 6. Statistical Fallacies
Statements & False Authority
• Def. People usually believe in numbers and experts without
• Def. A question or a statement that questioning them. Here statistics are used to misrepresent
conceals an opinion or assumption. rather than describe.
• Examples: • Examples:
– 3 out of 4 dentists prefer Crest. (Did Crest pick the dentists?)
– Do you still beat your dog?
– I surveyed 100 people and they all agreed with me. (I chose my friends).
– You don’t think that, do you? – Dr. X says this is the fastest and safest way to lose weight. (Did he/she get paid?
– All intelligent people agree that … 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?
Fix this by listening carefully and
separating fact from opinion.
7. Faulty Causal Relationship 8. Misleading Comparison
• Def. Mistakenly believing that two
(also called Post Hoc)
situations or people can be compared.
• Def. To excuse an action or belief by making it sound sensible.
Often this assumes that anything that came before an event caused • Examples:
it to happen. – Jill looks good in red. I’ll buy red pants, too.
• Example: – Forcing students to read books is like herding
– I stole the towel from the hotel. They expect people to take them.
cattle to slaughter.
– Eating 5 energy bars and drinking 2 Cokes helps me get better grades. I did
this and got an A on my history test. – You gave him extra time on the test, so I should
Fix this by examining the relationship between ideas. Make sure the get extra time too.
facts precede the theory and the reasons precede and cause the
– Saddam Hussien is Hitler.
belief.
Fix this by remembering that every person
and situation has different circumstances.

6. 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.