Professor Douglas W. Portmore
Lecture 1 – Introduction to the Course
Copyright © 2012 by Douglas W. Portmore
Last Updated: 7/12/2012
1. About the PowerPoint Presentations
*Redacted versions of these presentations are available under “Lecture
Outlines” in Blackboard.
*Some key words and phrases have been redacted from these lecture
outlines. These are noted in the lecture outlines by “[Redacted]” and
in the [Redacted] by underlining.
*To get the redacted portions of the lecture outlines, you must come to class.
Or, if you’re absent, come see me or one of the TAs in office hours. Or
you may ask someone in the class for his or her notes. But I do not,
under any circumstances, distribute un-redacted versions of my
*You should do more than just fill in the redacted words and phrases. I
sometimes use ellipses (‘…’) to indicate something particularly crucial
that you’ll need to fill in. And I often ask questions without having the
answers in the Presentation. You should always write down answers to
questions posed in the PowerPoint Presentations.
*All the possible exam questions for all of the lectures are collected in the
“List of Possible Exam Questions,” which is available under
“Handouts” in Blackboard. Study these as we progress through the
course. Don’t wait until a week before the test.
*Always be prepared to start on the next lecture. I often switch to a new
lecture in the middle of a class session.
*See the syllabus for which assigned readings are relevant to which lectures.
*In this lecture, I explain the theme for the course, specify what I hope for
you to get out of the course, and give you a brief primer on logic and
3. The Theme for the Course
*Most of you, as well as common opinion, are/is mistaken about the answers
to the foregoing important questions.
*And even if you’re not mistaken, you’re at least not entitled to being
confident in your answers—at least, not before giving these issues a lot
4. What do you believe?
a. Does God exist?
b. Do we have free will?
c. Is each of us both a mind/soul and a body?
d. Do you have knowledge of an external world, a world that exists
independently of your perceiving it? Do you know, for instance, that
someone is up at the front of the room speaking?
e. Do you know that you exist? f. Is it possible (not just physically possible, but possible in the widest
sense of ‘possible’) for you to survive the death and cremation of
your physical body?
g. Assuming that it was reasonable for you to believe that you have an
immortal soul and that this soul is the subject of your
consciousness, could it, then, be reasonable for you to anticipate
having conscious experiences after the death and cremation of your
5. What I’ll be arguing…
*In this course, I’ll be arguing (1) that God does not exist, (2) that we do not
have free will, (3) that we are not both a mind/soul and a body, (4) that
we do not have knowledge of an external world, (5) that you do not
know that you exist, (6) that it is not possible for you to survive the
death and cremation of your body, and (7) that it could not be
reasonable for you to anticipate having conscious experiences after the
death instruction of your physical body, even if it were reasonable for
you to believe both that you have an immortal soul and that this soul is
the subject of your consciousness.
*The positions argued for in this course are not necessarily the views of your
professor or the TAs. Indeed, I won’t even be consistent in the positions
that I argue for in this course. For instance, I’ll presuppose that you have
knowledge of an external world in one lecture and then argue that you
don’t have such knowledge in another.
6. Why is this the theme?
What is the point?
*The point is to challenge you to think, and to think hard, about your most
fundamental beliefs. So I’m going to be provocative, because the whole
point is to provoke you to think.
*This is all just an exercise in critical thinking. The point is to foster the
students’ abilities to think critically, to argue cogently, to assess
arguments, to analyze complex issues, to understand abstract concepts,
to attend to important distinctions, and to articulate various positions in
clear, precise, and unambiguous prose. The point is also to instill in you
the disposition to question orthodox opinion and, thus, to think for
*We could perform this exercise by reading, writing, and thinking about other
more mundane topics. But my hope is that the topics that I’ve chosen
will be considerably more thought-provoking and are in fact some of the
most important questions that there are.
*I will try to explain why these questions are important and explain how we
can make progress in answering them. And the course will help you to
hone the skills that you need to be able to answer these questions.
7. What’s an argument?
8. Continued… *An argument doesn’t have to be a good one.
*An argument isn’t the same as contradiction.
*“Argument is an intellectual process. Contradiction is just the automatic
gainsaying of anything the other person says.”
*“An argument [Redacted].”
*Note the use of the word ‘intended’. What’s its purpose?
9. A little bit of logic: Arguments
*Which, if any, of the following are true?
*An argument is just the automatic gainsaying of anything the other
*In order to argue with someone, one must adopt the contrary position.
*An argument is a set of two or more statements, one of which follows
from the others.
*An argument is a set of two or more statements, one of which purports
to follow from the others.
*Answer: B and D.
*Our official definition: X is an argument if and only if X consists in
contradiction, relating to one another’s point.
*The one that supposedly follows from the others is called the conclusion,
and the statements that supposedly support for the conclusion are
10. Some Examples
*Consider the following dialogue. Smith: “You’re an idiot.” Jones: “No, I am
not. Besides, you’re an ass.” Smith: “Well, at least, I don’t smell like
*Is this an argument?
*What about the following? “Since all dogs are mammals and all mammals
are animals, all dogs must be animals.”
*And what about this? “I’ve had two philosophy professors and they’ve both
been male. Therefore, all philosophy professors are male.”
*Yes. It’s an argument, but it’s a bad one.
*And this? “There’s no good reason to believe that God exists. So one
shouldn’t believe that God exists.”
*A statement is a sentence or independent clause that has a truth-value, that
is, a sentence or independent clause that is either true or false.
*X is a statement if and only if X is a sentence or independent clause that has
a truth value.
*X has a truth value if and only if X is either true or false.
*Give me an example of a statement.
*Give me an example of a sentence in English that isn’t a statement.
12. Continued… *Which are, and which are not, statements?
*What time is it?
*Sit up straight.
*Squares have three sides.
*A proposition is a truth or a falsehood that can often be expressed by a
number of different, but logically equivalent, statements. Two
statements express the same proposition if and only if they have
exactly the same meaning and, thus, always have the same truth
value. (Note that a statement is not a proposition. A statement
expresses a proposition.)
*Do the following pairs express the same proposition?
*(a) Smith is fallible. Smith is not infallible.
*(b) Bill is married. Bill has a wife.
*(c) Fred is unhappy. Fred is not happy.
*(d) Today is Sunday. Today is the day after Saturday.
*(e) Chris is a brother. Chris is a male sibling.
*(f) Chris is an uncle. Chris has a nephew or a niece.
*(g) Bill is a bachelor. Bill is single.
*A valid argument is one in which the truth of the premises entails (i.e.,
necessitates or guarantees) the truth of the conclusion. An argument is
valid if and only if, in no possible world, are all its premises true and its
conclusion false. Arguments that are not valid are invalid. (Note that
only arguments, and not statements or propositions, can be properly
called valid or invalid. By contrast, only statements and propositions, not
arguments, can be properly called true or false.)
*Does a valid argument have to have true premises? No *Does a valid argument have to have a true conclusion? No
*X is a valid argument if and only if it is logically impossible for all its
premises to be true while its conclusion is false.
*Is the following a valid argument:
*P1) If Bob studies hard, he will get an A.
*P2) Bob will get an A.
*C) Therefore, Bob studies hard.
*Is the following a valid argument?
*P1) All professional body builders are smart.
*P2) DWP is a professional body builder.
*C) Therefore, DWP is smart.
*Is the following a valid argument?
*P1) All dogs are mammals.
*P2) Some mammals are heavier than a ten ton truck.
*C) Therefore, some dogs are heavier than a ten ton truck.
*Is the following a valid argument?
*P1) If today is Monday, then Bill is not where he’s supposed to be.
*P2) Yesterday was Sunday.
*C) So Bill is not where he’s supposed to be