There is no one correct answer, but here is the one we will use, which is as good as any:
Logic is the study of arguments, in order to judge
or evaluate
them as good or bad or somewhere in between.
Sometimes it is said that logic is about how to think; but this is a misleading way to describe logic. Thinking is a process in your mind. The thinking process often leads to products. What you say, what you write, and how you act are products of your thinking. Other people do not have access to your private thought processes. They only have access to the products of your thinking. An argument is only one of many kinds of written or spoken thought-products, and logic focuses on evaluating arguments. Thus the connection between logic and thinking is rather indirect. Of course logic, like most subjects you study, will involve a good bit of thinking, but thinking is not the special subject matter of logic; cognitive psychology is the discipline whose subject matter includes thought processes.
Before long you will encounter some rules or guidelines for how to evaluate
arguments, but they will not be rules for what your inner thought
processes should be like. They will be rules for judging the quality of
certain thought-products: arguments (your own, or someone else's). Probably
studying logic will have some beneficial effect on your thought processes, but
that is not the major focus of logic. It's a fringe benefit.
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Here is our definition of an argument, which is a good bit more specialized then the everyday meaning of the word:
An argument is a group (a bunch, a set) of statements,
one of which
(the conclusion) is viewed by the speaker or
writer as following from
or being supported by the other(s) (the reason or
reasons).
Notice several things about the definition:
1. Every argument has a conclusion and it also has at least one reason, maybe more. So it takes a minimum of two statements to make an argument.
2. The definition implies that every argument is a group of statements, but it does not imply that every group of statements is an argument. Often people say or write things simply to give information (or misinformation), and they make no effort to prove that what they say is true. When this happens, which is very frequently, the result is a group of statements that is not an argument.
3. There is nothing in the definition about debating, disputing,
or disagreeing. An argument need not involve more than one person.
It is true that when people present arguments they very often are involved
in some sort of disagreement, but they don't have to be. An arguer
may try to prove something that no one on earth would doubt or disagree
with. And people may disagree without either of them presenting an
argument.
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Arguments, according to the definition, are made of statements. Statements (or, assertions) are rather special things. Here are two ways of explaining what a statement is. If you find one unclear, try the other!
1. A statement is a complete thought that can be expressed in a declarative sentence. It's the complete thought, not the sentence, that is a statement.
2. A statement is a thing that is capable of being true or false. In fact, every statement is either true or false (although you may not know which it is).
Here are some implications of these definitions of a statement: statements are not sentences, they are what (some) sentences express; different sentences can express the same statement; the same sentence can express different statements; one sentence can express several different statements.
Examples:
a) A mile is longer than a kilometer. A kilometer is not as long as a mile.
Example a) consists of two different sentences, but they say the same thing (in different words). That one thing that they both say is a statement. So these are two different sentences that express the same statement.
b) Suzie says: I'm hungry. Sam says: I'm hungry.
Suzie and Sam have uttered exactly the same sentence, but they haven't expressed the same statement. Suzie made a statement about Suzie, Sam made a statement about Sam. A re-expression of a given statement must be about the same person or thing. If Sam had said to Suzie, "You're hungry", then he would have been repeating (in different words) the same statement that she made.
c) Hard courses are better than easy courses, because you learn more in hard courses.
Example c) is just one sentence but it contains (or expresses) two statements that make an argument. The conclusion is first, the reason next.
d) What time is it?
Example d) is a sentence that does not express a statement at all, because a question isn't (normally) a thing that can be true or false.
Statements are sort of spooky, immaterial things. You can't see
or touch or hear them. You can only see or touch or hear the spoken
or written words that express them. The most important things about
statements are: 1) arguments are made of statements; and 2) different
sentences can express the same statement. If this statement business
seems complicated, there is really no need to be
overly concerned about it. It is complicated to explain, but
it's not hard to get the hang of it as we go along. Wait and see.
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4) HOW CAN YOU TELL THAT AN ARGUMENT IS BEING GIVEN?
There isn't any one simple answer to this question. A person presents an argument when she or he offers one or more reasons in an effort to support or prove a conclusion. Often you simply have to rely on your understanding of the context of the writing or speech or conversation to know whether an argument is present. Sometimes people just don't make it very clear whether they are giving an argument. Sometimes you will read a passage and you just won't be able to tell whether there is an argument present. Often that is not your fault; often it is due to lack of clarity on the part of the writer.
But often there is little doubt that an argument is present: when certain special words are used. We call these words and phrases inference indicators, or clue-words, or cue-words. They are words or phrases (sometimes even whole sentences) that tell you that some statement is being offered as a reason for some other statement. They indicate that the speaker or writer has made an inference, has reached a conclusion based on some reason(s). "Therefore" is used to indicate that a statement after it is a conclusion (and that a statement before it is a reason). "Because" works in the reverse direction: it indicates that the first statement after it is a reason (and, often, that the statement before it is a conclusion).
It is useful to divide inference indicators into two kinds, based on the status of the statement that comes immediately after them. Conclusions come right after conclusion indicators, and reasons come right after reason indicators.
Some Inference Indicators
Reason indicators: Conclusion indicators:
because
therefore
due to the fact that
so
is based on
thus
is proved by
which proves that
is shown by
which shows that
which follows from
from which it follows that
is a consequence of
consequently
since
which leads to
for
which is why
Two words of warning about these examples. First, there are so many inference indicator words and phrases that it would be hopeless to try to list them all. Second, and more important, the very same words can sometimes be and sometimes not be inference indicators -- simply because most words have more than one meaning. Whether a word or phrase is an inference indicator is a matter of how it is used in a particular context. Consider the word "since":
a) Tom is around here somewhere, since Jill saw him just a minute ago.-
Here "since" tells you that the next statement -- that Jill saw Tom -- is offered as a reason for the previous statement, that Tom is around here. Thus "since" in this case is an inference indicator that tells you a reason comes next. It has the same meaning as "because."
b) It's been a long time since I've seen a good movie.
In this case, "I've seen a good movie" is not being offered as a reason why it's been a long time! The "since" is not being used as an inference indicator; it is instead being used to indicate a length of time.
The bottom line about recognizing inference indicators is that you simply have to know what those little words and phrases mean. You may find that this involves a bit of vocabulary-building.
A third and final word of warning. Inference indicators are words or phrases that typically connect statements together -- they come in between words (sentences, clauses, phrases) that express statements. But not all "connective" words and phrases are inference indicators. Example:
Joe went to the cafeteria looking for Suzie, but he didn't find her there.
The "but" is a connective word that is not an inference indicator. It does not serve to tell you that one statement is being given as a reason for another. The statement that Joe went to the cafeteria looking for Suzie is not being offered as a reason why he did not find her! And the statement that he didn't find her isn't being offered as a reason why he went looking for her! The "but" does have a purpose. It suggests or indicates that there is a sort of contrast between looking for Suzie and not finding her. Here are some connective words that are never inference indicators:
but, however, moreover, in addition, furthermore, nevertheless
In conclusion: very often inference indicator words and phrases connect (come between) statements, but many of the words and phrases that connect statements are not inference indicators. To tell the difference, you just have to think about what the words or phrases mean. An inference indicator means "Hey, look: here comes a conclusion!"; or else it means, "Hey, look: here comes a reason!". Connective words (such as "but") that do not have such meanings are not inference indicators.
The structure of an argument is just the business of how the statements in an argument are related to each other as reasons and conclusions. If you don't correctly identify which statement(s) are reasons and which statement(s) are conclusions, you have misunderstood the argument.
So before we look at how to evaluate reasoning (i.e., arguments), we will first concentrate on how to represent or depict the structure of an argument. It involves learning how to draw an argument diagram. Here are the rules -- the step-by-step procedures -- for argument diagramming:
1. Put brackets (or parentheses) around words that express statements. The inference indicators and other connectives words should be outside your brackets, because they aren't parts of statements.
2. Put a number above each statement. Use different numbers for different statements, and use the same number again for repeats of the same statement.
3. Draw circles around all inference indicator words, and nothing else.
4. Write out a skeleton of the passage. Here's how to do it:
Copy everything in the passage (including your brackets and numbers) except for the words inside your brackets. The result will be the skeleton, or pattern, or "stencil" of the passage.
5. If the passage does not contain an argument, then just write "No argument" and stop. If there is no argument, there is no diagram. Diagrams are only for arguments!
6. If the passage does contain an argument, then:
Make a diagram by drawing arrows that point from reason-numbers toward conclusion-numbers; always put points on your arrows, and put a point on only one end of each arrow! And don't use the same number twice in a diagram.
The purpose of diagramming an argument is to get you to think carefully
about the structure of the argument and the importance of inference indicators
in figuring out the structure -- to focus your attention on correctly identifying
reasons and conclusions. For very simple arguments like those above
you really don't need a diagram to find out what is the reason and what
is the conclusion. But for more complicated arguments diagrams are very
helpful. When three statements are involved there are about fifteen
different possible ways of drawing the diagram! Usually only one
of them is right.
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INTERPRETING UNCLEAR ARGUMENTS
When the inference indicators in an argument aren't enough for doing an argument diagram, you have to interpret the argument for yourself. When a passage simply is not written clearly enough, you just have to use educated guesswork. It's not your fault when writers or speakers do not make the structure of their reasoning sufficiently clear!
A good a rule of thumb is The Principle of Charity: if one way of doing the diagram makes more sense than another possible way, then assume that the more sensible way is what was intended. Give the arguer the benefit of a doubt!
Of course sometimes each of several ways of doing a diagram is as sensible as the others. But think about the passage very carefully before you conclude that there is no basis for preferring one way of doing a diagram over another.
So far we have not been judging how good arguments are.
We've just been doing the diagrams. Later on we'll focus on evaluating
how good a piece of reasoning is.
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There are "mini-arguments" and "maxi-arguments," or, microarguments and macroarguments. A mini-argument is typically contained in just one sentence or one paragraph. A maxi-argument may extend over several paragraphs, or a whole essay, or a whole book! But maxi-arguments are made up of interrelated or intertwined mini-arguments, and these may be separated by large chunks of non-argumentative prose. The only reliable way to adequately evaluate a maxi-argument is to evaluate its component mini-arguments. That's why we are focusing on mini-arguments!
Most of the exercises we'll use are fairly clear examples of arguments, but outside of logic classes things are less straightforward. The English language is very flexible, and it is constantly changing and developing. In the final analysis, the key to recognizing arguments in everyday language is to read (or listen) carefully. Here are some complicating factors to be aware of.
1. Statements can be expressed in "shorthand" ways. Suppose someone asks whether you have seen the morning paper and you answer "No". You answer is just one word, but it amounts to the statement "I have not seen the morning paper". So that single word could be bracketed and numbered as a statement. Usually an answer to a question amounts to a statement.
Another way to express a statement with a single word is by using a
pronoun. Example:
1
We know that [the predictions of economists
are unreliable]. We know
1
2
[this] because [they so often predict
the opposite of what really happens].
The the antecedent of the pronoun "this" is statement 1; so the single word "this" is essentially a repeat of statement 1. Whether you actually number "this" as a repeat of [ 1 ] isn't terribly important. It would do just as well to circle the whole phrase "We know this because" as an inference indicator. The important thing is that you understand that [ 1 ] is a conclusion and that [ 2 ] the reason given to support it.
A third shorthand way to express a statement is through a noun phrase:
1
2
[The high rate of serious injuries]
proves that [motorcycle racing is a
very dangerous sport].
Although the noun phrase bracketed as [ 1 ] does not include an explicit subject and predicate, it nonetheless expresses a statement, because its meaning could be re-expressed as a declarative sentence:
Motorcycle racing involves a high rate of serious injuries.
2. Questions (interrogative sentences) sometimes express statements. "Do you know that the President held an important news conference this afternoon?" is not really a serious request for information. It is a way of telling you (in case you haven't heard) that the President held a news conference this afternoon -- a way of using an interrogative sentence to make a statement. Such questions that really make statements are usually called "rhetorical" questions.
3. Often arguments have unstated reasons or conclusions.
A speaker or writer may think that a reason or conclusion is so obvious
or so well-known that it doesn't need to be spelled out. Arguments with
"missing parts" are often called enthymemes. When diagramming
an enthymeme you should write out the missing reasons or conclusions, give
them numbers, and then include them in your diagram.
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