| I. We said last period that every argument in logic has a structure--every
argument in logic can be described in terms of this structure. |
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A. Premisses: statements which give
evidence for, or reasons for, accepting the conclusion. |
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B. Conclusion: statement which is
purported to be established or affirmed on the basis of other statements (the premisses). |
| II. Recognizing Arguments: Given these
characterizations, then, how do we sort out arguments from the rest of the kinds of
linguistic behavior? |
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In effect, what we are doing is separating the
territory of logic from the rest of the world. |
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In order to know to what we can apply our
powerful methods of analysis, we need to learn how to separate argumentative discourse
from non-argumentative discourse. |
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A. Typical argumentative "look-a-likes"
fall into four main categories. |
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1. Fiction, poetry, emotional discourse:
the purpose is not factual truth. |
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2. Commands: they are not statements
because they have no truth value. (However, they can be subjected to a "logic of
commands" as noted later.) |
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3. Conditional statements (by themselves)
are not arguments.: "If ... then ..." statements, sometimes called
"hypotheticals," although many logicians distinguish different various forms of
conditionals. |
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4. Explanations: their purpose is not to
prove, but to explain. In general explanations are not arguments. (Some good explanations
have a deductive character, as discussed below.) |
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B. Fiction, poetry, emotional discourse
are to be distinguished as well.. |
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1. Even though good fiction has a good internal
logic, there is usually no proof involved. |
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a. The truth in a story is like the
"ah-ha" experience of an explanation. |
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b. Our learning is indirect--i.e., we
perceive or understand the truth. |
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c. The investigation of the status of fictional
statements is an area in present inquiry. |
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d. The work of fiction, as a whole, can be
thought of as a very large conditional statement: |
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If {we assume characters, plot, etc.) then
{such and such statements logically follow}. |
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e. This proceeding is the sort of thing that is
done in thought-experiments. E.g., consider the main point of W.
Somerset
Maugham's Of Human Bondage: The Persian rug with its intricate design has no
purpose other than itself and is the metaphor of life itself. |
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2. Poetry's purpose is not to prove or
demonstrate, but to appeal to our emotions or insight. |
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a. Often these insights are alogical--hyperbole,
contrast, contradiction, analogy, etc., give us insight. |
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b. E.g., consider
Stephen Vincent Benét's "The Ballad of William Sycamore": |
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"So I saddled a red unbroken colt
And I rode him into the day there,
And he threw me down like a thunderbolt
And rolled on me as I lay there. |
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The hunter's whistle hummed in my ear
As the city men tried to move me,
But I died in my boots like a pioneer
With the whole wide sky above me." |
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To raise the question of how a dead man can write
a poem is to miss the point. |
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3. Emotional Discourse: in common
parlance, these "heated arguments" are alogical--the standards of logic are not
meant to apply. |
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a. E.g., "one man was shot, one man
was injured after a heated argument in a bar." |
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b. From a logical point of view, the heated
exchange is views is often settled by the doctrine that "might makes right." |
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C. Commands, especially those put as
imperative statements are not arguments. |
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1. Again, we could evaluate a series of commands
for logical consistency (as when we are told to do different things by the same
authority), but commands, strictly speaking, are neither true nor false, so they are not
normally part of arguments. |
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2. As we will see later, imperatives can function
as directive (e.g., "Study hard"), expressive (e.g., "Have a
nice day), or informative (e.g., "Study pages 25-140 for the test"). |
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3. Sometimes you should look at the
context—although imperatives are used, the passage might be meant to be an argument. |
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4. Consider the following quotation from Kurt
Vonnegut, Jr.: "Be careful who you pretend to be, for that you will surely
become." Is he explaining how pretense can be harmful, is he trying to prove it, or
is he warning us not to pretend? One could only tell by looking at the context in which
this sentence was used. |
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D. Conditionals look very much like arguments and
intuitively "feel" very much like arguments, but their antecedents are not
asserted to be true. They are no more than complex statements. (Often, we will analyze an
argument with conditional statements--e.g., as in the statement, "If the
premisses are true, then the conclusions will follow.") |
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1. The parts of a conditional: If {antecedent}
then {consequent} |
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2. If I say, "If someone fails this class,
then I will eat the textbook," I haven't proved anything. |
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3. A conditional can be thought of as
conditionally being an argument if the antecedent is true, but this is not at all what is
being asserted. However, in an argument the premisses are asserted as true. |
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4. Since conditionals are statements, then, of
course, they can be part of arguments: |
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Consider, the hypothetical syllogism |
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If I drop this book, then it will fall to the
floor. |
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If it falls to the floor, then it is heavier
than air. |
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Therefore, if I drop this book, then it is
heavier than air. |
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Or an argument form called modus ponens |
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If you study hard, then you make an A in
logic. |
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You study hard. |
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Therefore, you make an A. |
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D. How to distinguish arguments from explanations. |
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1. By carefully reading the text, you can discern
several important differences between an argument and an explanation. |
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a. Do a group of statements give evidence,
grounds, or reasons for some other statement? |
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b. Is the purported conclusion better known than
the purported premisses? |
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c. Is a causal connection asserted or implied? |
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d. What is the author's purpose in offering the
passage? |
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e. What is the context of the passage? |
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2. In general, these questions point to the
difference between arguments and explanations. (Nevertheless, arguments and explanations
do, on occasion, overlap.) |
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Argument |
Explanation |
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(1) expresses an inference |
does not usually express an inference |
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(2) offers evidence, grounds or
reasons |
offers an account why |
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(3) goes from well known
statements to statements less well known |
gives less well known statements why a
better known statement is true |
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(4) draws a logical connection
between statements |
describes a causal connection |
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(5) has the purpose to
establish the truth of a statement |
has the purpose to give an account of
something |
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3. Consider the following passage given in an
edition of Copi's Introduction to Logic: |
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(1) The Roman Empire collapsed because (2) it
lacked the spirit of liberalism and free enterprise. |
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a. Which statement is better known (1) or (2)?
Since the first statement is better known, we would say that this is an explanation which
shows a causal connection rather than an argument with a logical implication. |
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b. If the author were advancing the general
thesis "All countries that lack these attributes crumble to dust," therefore the
Roman Empire did, then a Deductive Nomological Explanation is being given.
In point of fact, this is precisely the argument which von Mises gives
in the original passage from which this passage was excerpted:
"The Roman Empire crumbled to dust because it
lacked the spirit of liberalism and free enterprise. The policy of
interventionism and its political corollary, the Fuhrer principle,
decomposed the mighty empire as they will by necessity always
disintegrate and destroy any social entity." Ludwig von
Mises, Human Action (Auburn: Mises,1949), 763.
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[All countries that lack the spirit of liberalism
and free enterprise crumble to dust.] I.e., contraposition
of the last sentence of the passage above. |
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The Roman Empire lacked the spirit of
liberalism and free enterprise. |
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Therefore, the Roman Empire crumbled to dust. |
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c. Very often, the Deductive Nomological Method
of Explanation is given as a method of ordering science into a deductive system. |
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Explanans |
L1, L2, ... ,
Lk General Laws |
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Logical Deduction |
C1, C2, ... ,
Ck Statements of Antecedent Conditions |
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Explanandum |
Description of the empirical
phenomenon to be explained. |
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D. The answer to why rainbows form on
gasoline-station driveways is expressed in terms of layers of different density fluids
with different optical properties. The index of refraction, reflection, wavelengths of
light, and the electromagnetic spectrum are all mentioned. Hence, the statements in
an explanation "move" from well known to less well known statements.
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Philosophy 103: Introduction to Logic
