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Prof. Courtright
PHL 205 LECTURE:
Hurley’s A Concise Introduction to Logic (11th Ed.)
CHAPTER 1: BASIC CONCEPTS
Sections 1.1 – 1.4
Alright, now down to brass tacks. Normally, I will not be so long-winded. The lesson plan that
follows is basically a reiteration of Hurley’s text. The only significant change is that I offer
different examples in order to illustrate a point. Here are my Prof’s Notes.
SECTION 1.1. ARGUMENTS, PREMISES, AND CONCLUSIONS
Hurley defines logic as “the organized body of knowledge, or science, that evaluates arguments”
(1). Ok, so that might be a good definition, but so what? What does logic have to do with life?
Where do we encounter arguments and why does it matter that we evaluate them?
We find arguments everywhere. Arguments are presented on TV, on Facebook, in books, and in
everyday conversations. Fine. The natural follow-up to this claim about the prevalence of
arguments is: What is an argument? We all think we know what an argument is, but in actual
fact, the things that we often call “arguments” are not actually arguments, but are statements of
opinion, explanations, or factual statements. Here is how Hurley defines an argument: “a group
of statements, one or more of which (the premises) are claimed to provide support for, or reasons
to believe, one of the others” (1). Basically, an argument consists of at least one premise and a
conclusion. The conclusion is the claim that is being argued for; that is, the claim that is being
presented as true. A premise consists of a statement that is meant to support the truth of the
conclusion.
Now, logic, as the science concerned with evaluating arguments, seeks not only to correctly
identify arguments, but to evaluate those arguments in order to determine whether they are good
or bad arguments. More on this in a moment . . .
Let’s dissect arguments further into their most basic units: statements. A statement is either a full
sentence or a sentence component (as in the case of compound sentences) that is either true or
false—i.e., a statement is usually a declarative sentence.
Examples of statements:
a. It is raining outside.
b. The president of the United States is Barack Obama.
c. No dogs are cats.
d. A Big Mac has 550 calories.
e. Conscientious objectors are communists.
f. There are no atheists in a foxhole.
g. Mississippi has deciduous and coniferous trees.
,Courtright Logic Lecture: Hurley Chapter 1 2
The first statement (a) is either true at a given time and place or it is false. The next three
statements (b) – (d) are true. Statements (e) – (f) are both false. Sentence (g) is actually
composed of two statements (“Mississippi has deciduous trees” and “Mississippi has coniferous
trees”), both of which are true. Truth and falsity are the two truth values of a statement.
Though some sentences are statements (and thus could be said to have truth values), there are
many sentences that are not statements, but are questions, suggestions, commands, exclamations,
and so on.
a. Why are the lights off in this room? (question)
b. We could order BBQ for dinner tonight. (proposal)
c. You should probably go to the doctor to have that spot checked out. (suggestion)
d. Get in the car right now! (command)
e. Excellent! (exclamation)
Here is an example of an argument:
All cars have wheels.
My Nissan Versa is a car.
Therefore, my Nissan Versa has wheels.
In this argument, there are two premises and a conclusion. It is very important to be able to
identify a conclusion and to distinguish it from the premises. How do I determine what the
conclusion is? The most important way is to ask: What is the main claim that the arguer is
seeking to persuade me is true? A conclusion is the statement that the evidence (premises) is
claimed to support. A premise is a statement that is set forth as evidence or a reason for holding
the conclusion to be true.
In the argument above, I must ask what claim the argument is seeking to persuade me is true. It
is not “My Nissan Versa is a car,” for that is being asserted as factually true without offering any
support for that claim. The conclusion is “my Nissan Versa has wheels”. The other two
statements are being offered as support for the conclusion. When I evaluate this argument, I will
discover that it is a good (valid) argument in that the premises support the conclusion.
Another (easier, but less reliable) way to determine which statement is the conclusion is to look
for indicator words or phrases. These are words that typically indicate whether a statement is
operating as a conclusion or a premise in an argument.
Conclusion indicators include the following: therefore, thus, hence, consequently, accordingly,
and so on. [Refer to the list on p. 3 of Hurley.] Generally speaking, the presence of one of these
indicator words identifies a conclusion.
E.g. Duane did not eat any carbohydrates before the 5K race today. Thus, he will not finish
the race with a fast time.
Premise indicators include: since, because, for, may be inferred from, seeing that, etc. [Refer to
, Courtright Logic Lecture: Hurley Chapter 1 3
list on p. 3 of Hurley text.] Generally speaking, the presence of one of these indicators signals a
premise.
E.g., Duane will not finish the race with a fast time because he didn’t eat any carbohydrates
before the race.
Sometimes one indicator can signal the presence of more than one premise.
E.g., Duane will not finish the race with a fast time today since he didn’t eat carbohydrates
before the race and he hasn’t been training regularly.
In the example above, the premise indicator “since” operates as an indicator for two premises:
(P1) Duane did not eat carbohydrates before the race and (P2) Duane has not being training
regularly for the race. These two premises provide evidence that supports the conclusion (C)
Duane will not finish the race with a fast time today.
NOTE: It is frequently the case that an argument will contain no indicator words at all. This is
why identifying the components of an argument using indicator words is ultimately not a failsafe
way to break down an argument. Instead, always seek to identify the conclusion first by asking:
What is the main claim that is being made in this passage? What is the main point that the
author/speaker/passage is trying to make? What claim is the author ultimately trying to
persuade me is true?
Example:
The quality of higher education depends upon proper funding. Without competitive salaries,
a university cannot hire the best professors. Further, if there is no money for student
scholarships, then the best students will not be attracted to that university. Finally, a properly
funded university will possess the technology necessary for success in training the leaders of
tomorrow.
The argument above contains no indicator words, but we can ask what is the main point that the
author is making here and does he or she offer any reasons to support that main point.
P1: Without competitive salaries, a university cannot attract the best professors.
P2: Without funding for student scholarships, the best students will not be attracted to that
university.
P3: A properly funded university will possess the technology necessary in order to
successfully train our future leaders.
C: The quality of higher education depends upon proper funding of the university.
NOTE ON ORDERING AND REPHRASING: When you are identifying the parts of an
argument and putting it back together, you must (i) put the argument into the proper order with
premises first (in the order in which they occur in the passage) with the conclusion following the
premises (even if the conclusion was stated before the premises in the passage). Also, (ii) you
must reformulate or rephrase the statements into complete and meaningful sentences if they do
Prof. Courtright
PHL 205 LECTURE:
Hurley’s A Concise Introduction to Logic (11th Ed.)
CHAPTER 1: BASIC CONCEPTS
Sections 1.1 – 1.4
Alright, now down to brass tacks. Normally, I will not be so long-winded. The lesson plan that
follows is basically a reiteration of Hurley’s text. The only significant change is that I offer
different examples in order to illustrate a point. Here are my Prof’s Notes.
SECTION 1.1. ARGUMENTS, PREMISES, AND CONCLUSIONS
Hurley defines logic as “the organized body of knowledge, or science, that evaluates arguments”
(1). Ok, so that might be a good definition, but so what? What does logic have to do with life?
Where do we encounter arguments and why does it matter that we evaluate them?
We find arguments everywhere. Arguments are presented on TV, on Facebook, in books, and in
everyday conversations. Fine. The natural follow-up to this claim about the prevalence of
arguments is: What is an argument? We all think we know what an argument is, but in actual
fact, the things that we often call “arguments” are not actually arguments, but are statements of
opinion, explanations, or factual statements. Here is how Hurley defines an argument: “a group
of statements, one or more of which (the premises) are claimed to provide support for, or reasons
to believe, one of the others” (1). Basically, an argument consists of at least one premise and a
conclusion. The conclusion is the claim that is being argued for; that is, the claim that is being
presented as true. A premise consists of a statement that is meant to support the truth of the
conclusion.
Now, logic, as the science concerned with evaluating arguments, seeks not only to correctly
identify arguments, but to evaluate those arguments in order to determine whether they are good
or bad arguments. More on this in a moment . . .
Let’s dissect arguments further into their most basic units: statements. A statement is either a full
sentence or a sentence component (as in the case of compound sentences) that is either true or
false—i.e., a statement is usually a declarative sentence.
Examples of statements:
a. It is raining outside.
b. The president of the United States is Barack Obama.
c. No dogs are cats.
d. A Big Mac has 550 calories.
e. Conscientious objectors are communists.
f. There are no atheists in a foxhole.
g. Mississippi has deciduous and coniferous trees.
,Courtright Logic Lecture: Hurley Chapter 1 2
The first statement (a) is either true at a given time and place or it is false. The next three
statements (b) – (d) are true. Statements (e) – (f) are both false. Sentence (g) is actually
composed of two statements (“Mississippi has deciduous trees” and “Mississippi has coniferous
trees”), both of which are true. Truth and falsity are the two truth values of a statement.
Though some sentences are statements (and thus could be said to have truth values), there are
many sentences that are not statements, but are questions, suggestions, commands, exclamations,
and so on.
a. Why are the lights off in this room? (question)
b. We could order BBQ for dinner tonight. (proposal)
c. You should probably go to the doctor to have that spot checked out. (suggestion)
d. Get in the car right now! (command)
e. Excellent! (exclamation)
Here is an example of an argument:
All cars have wheels.
My Nissan Versa is a car.
Therefore, my Nissan Versa has wheels.
In this argument, there are two premises and a conclusion. It is very important to be able to
identify a conclusion and to distinguish it from the premises. How do I determine what the
conclusion is? The most important way is to ask: What is the main claim that the arguer is
seeking to persuade me is true? A conclusion is the statement that the evidence (premises) is
claimed to support. A premise is a statement that is set forth as evidence or a reason for holding
the conclusion to be true.
In the argument above, I must ask what claim the argument is seeking to persuade me is true. It
is not “My Nissan Versa is a car,” for that is being asserted as factually true without offering any
support for that claim. The conclusion is “my Nissan Versa has wheels”. The other two
statements are being offered as support for the conclusion. When I evaluate this argument, I will
discover that it is a good (valid) argument in that the premises support the conclusion.
Another (easier, but less reliable) way to determine which statement is the conclusion is to look
for indicator words or phrases. These are words that typically indicate whether a statement is
operating as a conclusion or a premise in an argument.
Conclusion indicators include the following: therefore, thus, hence, consequently, accordingly,
and so on. [Refer to the list on p. 3 of Hurley.] Generally speaking, the presence of one of these
indicator words identifies a conclusion.
E.g. Duane did not eat any carbohydrates before the 5K race today. Thus, he will not finish
the race with a fast time.
Premise indicators include: since, because, for, may be inferred from, seeing that, etc. [Refer to
, Courtright Logic Lecture: Hurley Chapter 1 3
list on p. 3 of Hurley text.] Generally speaking, the presence of one of these indicators signals a
premise.
E.g., Duane will not finish the race with a fast time because he didn’t eat any carbohydrates
before the race.
Sometimes one indicator can signal the presence of more than one premise.
E.g., Duane will not finish the race with a fast time today since he didn’t eat carbohydrates
before the race and he hasn’t been training regularly.
In the example above, the premise indicator “since” operates as an indicator for two premises:
(P1) Duane did not eat carbohydrates before the race and (P2) Duane has not being training
regularly for the race. These two premises provide evidence that supports the conclusion (C)
Duane will not finish the race with a fast time today.
NOTE: It is frequently the case that an argument will contain no indicator words at all. This is
why identifying the components of an argument using indicator words is ultimately not a failsafe
way to break down an argument. Instead, always seek to identify the conclusion first by asking:
What is the main claim that is being made in this passage? What is the main point that the
author/speaker/passage is trying to make? What claim is the author ultimately trying to
persuade me is true?
Example:
The quality of higher education depends upon proper funding. Without competitive salaries,
a university cannot hire the best professors. Further, if there is no money for student
scholarships, then the best students will not be attracted to that university. Finally, a properly
funded university will possess the technology necessary for success in training the leaders of
tomorrow.
The argument above contains no indicator words, but we can ask what is the main point that the
author is making here and does he or she offer any reasons to support that main point.
P1: Without competitive salaries, a university cannot attract the best professors.
P2: Without funding for student scholarships, the best students will not be attracted to that
university.
P3: A properly funded university will possess the technology necessary in order to
successfully train our future leaders.
C: The quality of higher education depends upon proper funding of the university.
NOTE ON ORDERING AND REPHRASING: When you are identifying the parts of an
argument and putting it back together, you must (i) put the argument into the proper order with
premises first (in the order in which they occur in the passage) with the conclusion following the
premises (even if the conclusion was stated before the premises in the passage). Also, (ii) you
must reformulate or rephrase the statements into complete and meaningful sentences if they do
