Intro to Logic

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  Intro to Philosophy  

   - Syllabus

   - Homework

   - Study Guide

   - Links

  Intro to Humanities

   - Syllabus

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The unexamined life is not worth living.




Pythagoras defined philosophy as the love of wisdom. Philia is Greek for love, and sophia means wisdom.




Presentation PPT







Which of these questions do you think are philosophical questions?


What is the good-life?


What ideas did you acquire unconsciously?


What is the meaning of life?


Pablo Neruda asked, "Why don't yellow birds lay lemons?"


Why can't we tickle ourselves?


Why does cold water sink, but frozen water floats? What would happen if ice sank?


Do we have freewill, or is everything determined?


Is the death penalty just? Why do we prevent inmates on death row from committing suicide - or donating their organs? Savio DSilva asked, "Why do they use sterilized needles for death by lethal injection?" View more. Are victimless crimes Just?

What is Justice?


Is it sometimes moral to steal or lie? What would happen if everybody lied - what if nobody lied? Do people ever help other people for unselfish reasons? What is morality? Does morality change?

Are people who make 600,000 a year happier then people who make 60,000 a year?  What is happiness? What is the good-life?

Should we sensor the media?

Do we know anything for certain? What is knowledge?




There are three questions we can ask when determining the value of ideas. Is it clear, coherent, and confirmable?



An idea or belief cannot be ambiguous or vague. Ambiguous ideas have multiple meanings. When we refer to God we need to clarify if we are talking about Christ, The Holy Spirit, That which no greater can be thought to be, or some other concept.

Vague concepts don't have clear boundaries. Examples are: baldness, manhood, infant, big, and small.



Our beliefs must be consistent, and not contradict themselves. Are these beliefs consistent:

We have free will. Every event has a cause.

The world is physical. Perceptions are nonphysical and direct.

Consciousness results from neurons. God is conscious.

Incest is immoral. We are descendents of Adam and Eve.



Are our beliefs justified? Do they conflict with empirical facts? Which of these beliefs conflict with experience:

Socrates said that, "To know the good is to do the good."

People are basically good. People are basically bad.

No good deed goes unpunished.





Aristotle (384-322 B.C.) Created the first system of logic.
His system was concerned with classes and syllogisms.



Propositional or deductive logic is about propositions. Propositions are statements, or sentences, that are true or false.

Which of the following statements do you think are propositions:

Theaetetus was younger than Socrates.

Socrates was a philosopher.

Know thyself.

Socrates taught Plato.

Plato taught Aristotle.

What is beauty doing here?



In an argument there are one or more premise, and there is only one conclusion. The conclusion is said to follow from the premises. The premises support the conclusion. They offer proof or evidence that the conclusion is true. The premises and the conclusion are all propositions.

Here is an example of an argument advanced by Democritus (460 - 370 B.C.E.):

1). If motion exists, atoms exist in a void. (premise)
2). Motion exists. (premise)
------------------------------------------------------- (therefore)
3). Atoms exist in a void. (conclusion)



In a valid deductive argument it is impossible to have all true premises and a false conclusion.

All men are mortal.
Socrates was a man.
Therefore Socrates was mortal.


All pigs are mortal.
Socrates was a pig.
Therefore Socrates was mortal.

Sound Arguments:



A sound argument a valid deductive argument that has all true premises.


If Kant was a philosopher, then Plato was a philosopher.
Kant was a philosopher.
Therefore, Plato was a philosopher.

This is a sound argument. All the premises are true, and the conclusion follows necessarily from the premises.


Inductive Argument:

An inductive argument is an argument were if we assume that the premises are all true, then the conclusion is probably true.


Strong Arguments:

A strong argument is an inductive argument were the premises supply probable support for the conclusion. For example:

This barrel contains 100 apples.
80 apples selected at random were ripe.
Therefore, all 100 apples are ripe.

Weak Arguments:

A weak argument is an inductive argument were the premises do not provide probable support for the truth of the conclusion. For example:

This barrel contains 100 apples.
3 apples selected at random were ripe.
Therefore, all 100 apples are ripe.

Cogent Argument:


A cogent argument is an inductive argument that is strong, and all the premises are true. The conclusion of every cogent argument is probably true.



- Metaphysics is the study of the basic nature of reality.  Traditional branches are cosmology and ontology. Cosmology is the study of the universe. Ontology is the general study of reality, types of being, what can be said to exist, and how they should be categorized.

- Epistemology is the study of the nature and scope of knowledge. Skepticism is the belief that knowledge is impossible.

- Ethics is moral theory. The main branches are applied ethics, meta-ethics, and normative ethics. Meta-ethics asks whether absolute moral truths exist, and how we can know them. Normative ethics asks what act, or personality traits,  are good or bad.

- Political philosophy is the study of government. It includes justice, law, and property.

- Aesthetics is concerned with art and beauty.

- Logic is the study of proper reasoning.


- Philosophy of mind deals with theory of mind.  One of it's main concerns is the mind body problem.

- Philosophy of language

- Theology is theory of God.



The PhD is the highest degree. It stands for Doctor of Philosophy.


Did you know that lawyers have PhD degrees. In other countries they have the title of Doctor, but in this country they don't.




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