Philosophy 101 – Epistemology and other topics
Epistemology: What is truth?
How does knowledge differ from mere opinion?
Mind-Body Problem: What is mind?
Is mind brain/matter or is it soul/immaterial?
Could computers have minds?
Free Will: Is determinism true? Or indeterminism?
What would constitute freedom? Do we have it?
Philosophy is a systematic examination of the rational grounds for our beliefs.
Philosophers question common sense and axioms.
What is truth?
Knowledge vs. mere belief: Knowledge requires truth and evidence, belief is either true or false.
Theory of truth:Aproposition is true if and only if the World is as the proposition describes it as being.
Fallacy of equivocation: using same word or phrase in 2 or more distinct ways.
Ex. Ray Charles is blind, love is blind, God is love.
Therefore, Ray Charles is God.
Two ways an argument can go wrong: 1) It may have false premises
2) Reasoning is poor
More than one sentence can express the same proposition. One sentence can express more than one
Adeclarative sentence is a string of grammatical words.Aproposition is what the sentence
What is truth?
Two important consequences of the correspondence theory of truth
1. Aproposition is either true or false and it is not necessary that anyone know its truth or falsehood. Nor is it
necessary that it be possible for anyone to know its truth.
2. Aproposition is true or false independently of these beliefs of the people who contemplate it (except
Adinosaur stood here 100 million years ago.
There are an even number of stars in our galaxy.
2 + 2 = 4
We cannot confuse what is true or false with whether we can know what is true or false. *Aclaim on someone’s belief or knowledge: ie. Chris believes 2 + 2 = 4 (exception of #2), Chris knows 2 + 2 = 4 (
The exception is when the claims themselves are about belief or knowledge
Knowledge is a success term. We restrict its use for what is true.
Truth is a part of knowledge. It’s one condition of knowledge.
X is a necessary condition for Y. If you have Y, then you have X.
X is a sufficient condition for Y. If X, then Y.
Truth is necessary for knowledge, but not sufficient. If you have knowledge, that’s sufficient to have truth.
If getting run over is sufficient for death.
If run over steam roller, then dead.
Being male is sufficient for being a bachelor.
If bachelor, then male.
If someone knows something, then it’s true. But maybe no one knows anything. What the fuck.
What is an argument?
An argument is a set of statements including premises and conclusions.
The premises are the reasons for thinking the conclusion is true.
Two basic kinds of arguments: deductive and non-deductive.
If all the premises are true, then the conclusion must be true.An argument that has this property is known as
Ex. Math. Think of the axioms as premises and theorems as conclusion.
Ex. Either p or q or r must be truth
But you also know NOT Q, NOT R, so P.
Consider the following: If Chris lives in BC, then Chris lives in Canada. Chris lives in BC/ Chris lives in Canada.
This sort of argument is known as modus ponens. It’s not a matter of what the claims are about, it’s about its logical
The nice thing about deductive arguments is that if you know that your premises are true, then so is your
Consider the following: Chris lives in Canada, so Chris lives in BC. This is deductively invalid as the reasoning is
bad. An argument may also be deductively invalid if the premises are false.
Logic is about the special kind of relationship between the premises and conclusion.
Consider the following: If the moon is made out of cheese, then I can eat it. The moon IS made out if cheese, so I
can eat. This is another example of modus ponens. It is deductively valid but the premises are false, so the
argument is false.
Deductive arguments can be flawed in two basic ways.
(1) One or more of the premises may be false
(2) The argument is invalid. An argument that goes wrong is either way is called unsound.Asound argument is one in which both its premises
are true and the conclusion follows from the premises (valid).
Fallacy of affirming the consequence. If P, then Q. Q, therefore P. This form deductively invalid.
If P, then Q. P, so Q. This is the deductively valid form, regardless of whether the premise is true or false.
Deductively valid arguments
Conclusion\Premises All true Not all true
True Possible Possible*
False Impossible Possible
*all cars have four wheels.
I own a car, it has four wheels.
If you are a pig, then you can fly.
Porky is a pig, so Porky can fly.
Monday, September 9, 2013. Lecture 3
Deductively valid arguments.
- Likelihood principle
- Only game in town fallacy
Intro to Philosophy of Religion
Asound argument is one where all the premises are true and it is deductively valid. Asound argument by definition
has a TRUE conclusion.
The truth of the conclusion has to logically follow.
1) If some guy texts my girlfriend to “come over,” then he is having sex with her.
2) Some guy did text her “to come over”
C) He is having sex with her
This is deductively valid (If P, then Q. P, therefore Q, modus ponens). The problem with this argument is not the
logic, it is the premises. The first premise is false. However, depending on who you fill in the place of “some guy”
and “girlfriend”, the premise may be true and thus the conclusion will be true.
These are either stronger or weaker, their strength is a matter of degree. Non-deductive arguments are used in
science and in ever