Dr. P.J. Boulos
Reasoning:
Reasoning is basically the process of "drawing" conclusions. We can either (1)
investigate or inquire or (2) deliberate. (1) is problem solving and (2) is
decision making. To inquire is in some sense to determine what is "true" or
worthy of belief. To deliberate is to decide what to do. As we progress we
will see what are some good techniques to use so that our reasoning is good.
I would like you to keep in mind, though, that an open mind and a
willingness to reflect and critique yourself and others are good tools to have.
Since reasoning is, for the most part, the art of drawing conclusions (which
are themselves statements) from some information (which is provided in
statements) we will spend some time learning how to "compartmentalize" the
information we can gather from the passages presented to us. You should
realize that this is by no means the only to communicate -- it is just one way
among many. We saw (last class) that, unlike interrogations, exclamations,
or commands (imperatives), the most direct way to convey information
through language is to make statements. Consider the following:
Statement: Pat loves Star Trek.
Interrogation: Does Pat love Star Trek.
Command: Pat, love Star Trek!
Now, aside form the grammar of the sentences above, what we will call
statements are the types of utterances or sentences which "say" something
about the way things or the world is. That is, statements purport to present
an idea as true or as correctly depicting the way the world is. When you
assert the statement "Pat loves Star Trek" you are asserting the proposition
that he or she odes indeed love Star Trek. In other words, you are proposing
the "fact" Pat loves Star Trek as actually being the case.
A related topic to asserting is the act of implying. What we are asserting in a
claim is essentially the fact that a proposition is true simply by uttering or
writing words which express that proposition. For example, in a discussion
about the relative merits of two different cars you may state: The Diamond is
a fine handling car, but the Neptune has a high performance balancing
system." You would be, in this statement, implying something you haven't
explicitly claimed, namely that the Diamond does not have a high
performance balancing system.
Notice that implying is a method of conveying information without asserting
it explicitly. There are other methods of conveying information indirectly --
innuendo and irony (sarcasm). Again in innuendo and irony, it is intended
that the audience draw the appropriate conclusion. The backdrop to all of
this is composed of the words used along with the context under which they
were used. In innuendo, the speaker or writer hints at a proposition rather
than stating it explicitly, whereas in the case of irony the speaker or writer
employs a figure of speech in which the intended meaning is the opposite of
what is expressed by the chosen words.
Finally, another way of conveying information is the attribution of a claim to
someone else. We frequently do this by directly quoting someone, indirectly
quoting (paraphrasing), or ascribing a belief to that person. To directly quote
is to report the exact words a person used. You would be indirectly quoting
them if you conveyed their asserted ideas without repeating the exact words
they used. Related to indirect quoting is the ascription of belief : this is the
process of reporting what another person thinks, supports, concludes,
believes, and so on.
Inference
Sometimes it is not obvious that a conclusion is missing. Recasting the
argument will be beneficial in such situations.
Example:
If most Canadians recognize the energy problem, the prime minister will be
able to take strong action. But everyone who watches the news recognizes the
energy problem. And most Canadians watch the news.
We begin by treating each of the three statements in the passage as the
conclusion of the argument.
a)
1. If most Canadians recognize the energy problem, the prime minister
will be able to take strong action.
2. Everyone who watches the news recognizes the energy
problem.
So,
3. Most Canadians watch the news.
b)
1. If most Canadians recognize the energy problem, the prime minister
will be able to take strong action.
3. Most Canadians watch the news.
So,
2. Everyone who watches the news recognizes the energy problem.
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c)
2. Everyone who watches the news recognizes the energy problem.
3. Most Canadians watch the news.
So,
1. If most Canadians recognize the energy problem, the prime minister
will be able to take strong action.
None of these readings seem to adequately convey that the intended
conclusion is supported by the premises. Perhaps the conclusion is only
implicitly stated:
1. If most Canadians recognize the energy problem, the prime minister
will be able to take strong action.
2. Everyone who watches the news recognizes the energy problem.
3. Most Canadians watch the news.
So,
????
2. and 3. together seem to imply that most Canadians recognize the energy
problem. This taken with the first premise would entail the implicit
conclusion: The prime minister will be able to take strong action. The full
argument, then, will look something like the following:
1. If most Canadians recognize the energy problem, the prime minister
will be able to take strong action.
2. Everyone who watches the news recognizes the energy problem.
3. Most Canadians watch the news.
So,
4. The prime minister will be able to take strong action.
Problem of Missing Premises
This is, perhaps, more common than implicit conclusions. There are
situations where both occur.
The Surgeon General has determined that smoking is dangerous
to your health. Therefore, you should avoid smoking.
Recasting the argument entails:
1. The Surgeon General has determined that smoking is dangerous to
your health.
Therefore,
2. You should avoid smoking.
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Here there seems to be a logical gap between the premise and the conclusion
that could be closed with the following statement;
Health is valuable and should not be sacrificed.
Perhaps the person advancing the argument did not explicitly state this
statement. This missing premise or presupposition is something everyone
would probably maintain (i.e., it is commonly accepted) and seems to be
something the arguer would maintain. Recasting this argument we get:
1. The Surgeon General has determined that smoking is dangerous to
your health.
3. Health is valuable and should not be sacrificed.
Therefore,
2. You should avoid smoking.
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Inference (Continued)
• In presenting arguments people often: repeat themselves, digress, add
rhetorical flourishes such as "Of
course, everybody knows that
...,"
supply
premise
and
conclusion indicators along the
way, and use language in other
ways not pertinent to the
argument itself.
• Many argumentative passages do not fit neatly into the general schema of
arguments, namely:
P1
·
·
·
PN
—C
• Re-constructing arguments to fit this form: standardization
• This process is often done naturally or in "psychological" reconstructions
• For example:
Drinking alcohol should be made illegal,1 because it greatly increases
the likelihood of fatal car accidents,2 and shortens the imbiber's life
expectancy drastically.3
can be recast as follows:
(2) Drinking alcohol increases the likelihood of fatal car accidents.
(3) Drinking alcohol shortens life expectancy drastically.
Therefore,
(1) Drinking alcohol should be made illegal.
Standardize the following arguments:
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#1.
#2.
The use of aerosols disrupts the ozone layer of the atmosphere. This
poses a serious threat to health because it subjects humans to deadly
radiation. The use of aerosols ought to be banned.
Consider that we would not call something an explanation unless we
could completely express it because the function of an explanation is to
make what it explains intelligible and something is intelligible only if
it can be expressed. But a statement that is infinitely long is one that
cannot ever be fully stated or expressed.
Thus, no complete
explanation can be infinitely long. (Philosophical Problems and
Arguments: An Introduction, James W. Corman and Keith Lehrer)
Solutions:
#1. (1) The use of aerosols disrupts the ozone layer of the atmosphere.
(2) Disruption in the ozone layer poses a serious threat to health.
Therefore,
(3) The use of aerosols ought to be banned.
#2.
(1) The function of an explanation is to make what it explains
intelligible.
(2) Something is intelligible only if it can be expressed.
Therefore,
(3) Something is not an explanation unless it could be completely
expressed.
(4) An infinitely long statement is one that cannot ever be fully
expressed.
Therefore,
(5) No complete explanation can be infinitely long.
STRATEGIES FOR STANDARDIZING ARGUMENTS:
1. Determine whether passage is an argument.
2. Identify conclusion(s).
3. Identify premise(s).
4. Omit background or aside information.
5. Omit repeated information.
6. Omit personalized phrases.
7. Number premises and conclusion.
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8. Turn each premise and the conclusion into a stand-alone statement.
9. Check that all of the argument is portrayed.
Examples:
#1.
If a car has reliable brakes, it has brakes that work in wet weather.
The brakes on my car don't work very well in wet weather. You can
see that my car does not have reliable brakes.
Standardization:
(1) If a car has reliable brakes then its brakes work well in wet
weather.
(2) My car does not have brakes that work well in wet weather.
Therefore,
(3) My car does not have reliable brakes.
#2.
Weapons tend to make people fearful and distrustful. Fear and
distrust often lead to hostility. Therefore, building up weapons is
likely to cause hostility between nations.
Standardization:
(1) Weapons tend to make people fearful and distrustful.
(2) Fear and distrust often lead to hostility.
Therefore,
(3) Building up weapons is likely to cause hostility between nations.
#3.
Either the butler committed the murder or the judge committed the
murder. Since the butler was passionately in love with the victim, it
was not he who committed the murder.
Therefore, the judge
committed the murder.
Standardization:
(1) The butler was passionately in love with the victim.
Thus,
(2) It was not the butler who committed the murder.
(3) Either the butler committed the murder or the judge committed the
murder.
Therefore,
(4) The judge committed the murder.
Evaluating Inferences
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For each of the following inferences, evaluate the (i) the acceptability of the
premises and (ii) evaluate the strength of the inference using the criteria in
your book and what has been taught in class.
1. The History Instructor Case
(1) The textbooks selected for the history course were hard to read.
(2) The assignments for the history course were difficult to complete.
(3) Many students do not enjoy studying history.
Therefore,
(4) The instructor in the history course was not competent in her knowledge
of history.
2. The Recycling Case
(1) Recycling of newspapers and bottles will not alter the basic facts of over
consumption and overpopulation.
(2) The basic facts of over consumption and overpopulation are fundamental
causes of the global environmental crisis.
Therefore,
(3) Recycling of newspapers and bottles, though valuable in its own right, will
not suffice to solve the global environmental crisis.
3. The Academic Cheating Case
(1) Plagiarism is the representation of another person's work as one's own
and cheating is not.
So,
(2) Cheating on an examination is a lesser offense than plagiarism.
And,
(3) The penalty for plagiarism is failure in the course.
(4) There is no suitable penalty for cheating on an examination that is both
less than failure in a course and enough to mean something to the student
penalized.
Therefore,
(5) There should be no penalty imposed on students for cheating in an
examination.
4. A Professor Generalizes about Logic Students
(1) Students in my present logic class do not work as hard as students in my
logic class last year.
Therefore,
(2) Students at the university in general are not working as hard this year as
they did last year.
And,
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(3) Affluence and low standards in the high schools produce poor work habits
in students.
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