An essential aspect of good
writing is good reasoning. When you present your position, you want to be
certain that the reader does not dismiss you because of obvious logical
inconsistencies. The following schemas of the reasoning process can help
you to analyze your own writing and the writing of others.
The reasoning process according to
Stephen Toulmin has developed a straightforward diagram
of the reasoning process that is easy to understand and apply.
The first part of the diagram is the "Claim."
The Claim is a debatable assertion about the nature of things, such as,
"Marty and Jane would not be splitting up if Marty had treated her with
more respect." This statement is an assertion or an opinion which can be
The second part of the diagram is the "Grounds."
Grounds ----------------------------> Claim
The Grounds is the body of evidence that a person can produce to
support the claim. For instance, in our example the Grounds might be, "He
never let her finish telling her side of the story without interrupting or
shutting her off." This statement is evidence [that Marty did not treat
Jane with respect.
The third part of the diagram is the "Warrant."
The warrant explains how the Grounds supports the Claim. For example,
we might say, "Cutting someone off is a sign of disrespect."
The fourth part of the diagram is the "Backing."
The Backing explains the "givens," i.e., the cultural assumptions or
the theoretical basis for the warrant, as in, "Given our tacit
understanding that holding the floor is a sign of authority." So far, we
have a string of reasoning that sounds like this: "Given our tacit
understanding that holding the floor is a sign of authority, cutting
someone off is a sign of disrespect. Therefore, when Marty repeatedly cut
off Jane, he was showing his disrespect for her. If he had shown her more
respect, they would not be splitting up now."
The fifth part of the diagram is the "Rebuttal."
The Rebuttal is an "unless" statement: it explains conditions under
which the string of reasoning to this point would NOT hold. For instance,
the rebuttal in our example might be, "Unless Jane grew up in a family in
which it was common for people to cut each other off without giving
The sixth, and final, part of the diagram is the "Modality."
The "Modality" is a word or phrase that indicates the level of belief
or certainty the speaker has in the claim, as in, "If Marty had shown Jane
more respect, they CERTAINLY would not be splitting up now." Other
"Modality" or "Qualifier" phrases include "in my opinion," "without a
doubt," "probably," and "perhaps."
The full argument developed in our example, therefore, would be:
||Given our tacit understanding that holding the floor is a sign
||cutting someone off is a sign of disrespect. Therefore, when
||Marty repeatedly cut off Jane, he was showing his disrespect for her.
||If he had shown her more respect, they [certainly] would not be splitting up now,
||unless, of course, Jane grew up in a family in which people cut each other off all the time without giving offense.
An hypothetical environmental example might be:
||Given that high levels of faecal pathogens are the primary cause of loss of water-based recreation, and that
||sewer overflows are the main source of human pathogens, therefore
||because there are up 25% fewer swimming days in Dirty Harbour compared to Beautiful Cove
||the known sewer overflows from the Dirty Water trunk mains in the Dirty Harbour catchment are [highly likely] to be the source of reduced amenity
||unless there are other significant, unidentified sources of pathogens.
Although Toulmin's model contains these six parts of the reasoning
process, this does not mean that all six parts will always be stated
explicitly in an argument. Nevertheless, to analyze your own arguments or
the arguments of others, you can try to diagram the argument using this
pattern. If the argument does not state all of the parts, then you should
figure out what those parts would be if they were stated. These unspoken
parts of the argument are often taken-for-granted assumptions which may or
may not be able to withstand scrutiny.
For a thorough presentation of Toulmin's model, see Stephen Toulmin,
Richard Rieke, and Allan Janik, An Introduction to Reasoning,
Authority, Testimony, and
Quoting an expert (Authority), lining up the
testimonies of people who have seen or experienced something, and quoting
statistics are all forms of argument which Aristotle called "Inartistic
Arguments." Unlike enthymemes and examples, which the writer or speaker
makes up for the specific argument out of her own head, these arguments
are not created; instead, they are simply used. (Artistic and inartistic,
in this context, mean made or unmade.)
When you read someone's argument, or hear it on
television, you should be careful to judge the authority of the experts
who are cited. Here are a few questions to consider:
- What are the expert's credential's?
- What is the expert's reputation among various groups?
- Is the expert partisan or biased on this issue?
- Is there reason to believe that his or her judgment is being
influenced by allegiances or payments?
- Is the expert an expert on this subject or on some other?
- Does the expert have up-to-date information?
- What kind of reasoning and evidence does the expert supply?
Testimony is a strong argument. People testify to
what they have seen, heard, and experienced. As with authorities,
witnesses may be biased because of payment or allegiance, but if you have
already considered that possibility, then you should also consider these
questions as well:
- Are there inconsistencies in the story?
- Does the person seem to have the mental capabilities to remember and
- What point of view is the person telling the story from?
- Does the point of view block out some information or color it?
- Is there some reason why the person would be testifying for reasons
other than to tell the truth? (for fame, for money, for personal favors,
- How does the story fit with things that are already known?
- Could the witness have gotten this information through some means
other than by direct observation?
- Were there distractions that might have skewed the witness's
Statistics carry a lot of weight in our society.
They seem to be incontrovertible evidence in support of a position because
they carry the aura of scientific accuracy. However, a healthy suspicion
of statistics is warranted because of the way some people have used them to
mislead the audience. Here are some questions to consider when faced with
- How much of the methodology is the person revealing?
- If the statistics come from a survey, do you have access to the
questions that were asked? If so, try to think of how the questions
might have skewed the responses. It is often the case that people who
conduct surveys in order to prove their own biases have crafted the
questions in a way that will produce misleading results.
- How large was the sample? The reliability of statistics increases
with the size of the sample. A survey of 500 or 1,000 is more reliable
than a survey of 50 or 70.
- How was the sample selected? If the population surveyed was not
selected according to rigorous rules of sampling, the results can be
- What percentage of the people surveyed responded? If the survey
was mailed out, only a small portion of the recipients will respond,
and they often do so because they are in some way not representative
of the larger population.
- What was the level of significance of correlation? Statistics get
complicated when we start talking about numbers and specific
statistical methods, so it is best to take a course on the subject,
but even if you don't understand what the numbers mean, it is
important to see if the level of significance is reported. If it
isn't, the writer or speaker is asking you to place your faith in him
or her without giving you access to important information.
- How recent is the study?
- Who conducted the study?
- Is there reason to believe that whoever conducted the study was
trying to produce evidence for a position to which he pays allegiance?
- Are there other statistics which contradict the ones being reported?
The Syllogism and
In classical rhetoric, the "Enthymeme" is
considered a rhetorical syllogism. These terms are very old, coming down
to us from the ancient Greeks. To understand how we use enthymemes to
argue our case, we have to understand the basic syllogism.
To do justice to the syllogism, we would have
to take a course in logic. We can't do that here, so let's just look at
the basic syllogism. A syllogism is a deductive argument composed of three
statements. Deductive (the adjectival form of "deduction") means that the
argument starts from a general principle and reasons to the specific
instance. (Inductive would mean reasoning from the specific instance to
the general principle - as in "inductive" statistics.)
The first statement of a syllogism is called the Major Premise. It is a
broad generalization that associates two categories. The classical example
is "All men are mortal." Here the category of men and women is associated
with the category of things that die.
The second statement of a syllogism is called the Minor Premise. It
associates a single instance with the first of the two categories in the
Major Premise: "Socrates is a man." In this statement, a single instance
(Socrates) is associated with the first category (men) in the Major
The third statement of the syllogism is called the Conclusion. It
associates the single instance in the Minor Premise with the second
category in the Major premise, as in "Therefore, Socrates will die."
Here's the whole thing:
All men are mortal.There are many variations of
the basic syllogism, and there are many principles in logic that help you
analyze the truth value and validity of syllogisms. It's a good idea to
take a course in logic or practical reasoning if you have a chance.
Socrates is a man.
Socrates will die (or is mortal).
Aristotle said that the Enthymeme is a
rhetorical syllogism. A lot of ink has been spilled over the past 2300
years trying to explain exactly what that means. As with the syllogism, we
can't do full justice to the concept in this context, but we can describe
Most scholars of rhetoric now agree that an enthymeme is a syllogism
that leaves out one of the premises. For instance, instead of the full
syllogism stated above, an enthymeme would be:
Because Socrates is a man, he will die.In this
instance, the Major Premise of the syllogism is left out, and the Minor
premise is put in the form of a subordinate clause. The Conclusion of the
syllogism appears as the main clause of this sentence. Enthymemes will not
always follow this pattern, but they often do.
Rhetoricians point out that the enthymeme is a powerful form of
argument because of the missing premise. Sometimes, an audience will not
even notice that the premise is missing and they will give assent to the
enthymeme even though they would reject it in its full syllogistic
formation (because they would reject the missing premise). In other cases,
they subconsciously supply the missing premise from their fund of
taken-for-granted truths. When they do that, they are helping to make the
argument themselves because they are supplying part of it. As a result,
they tend to believe the enthymeme even more fervently because their own
assumptions have been woven into it.
A good thing to do with your own writing and the writing of others is
to look for enthymemes and then attempt to reconstruct the syllogism on
which it is based. We all rely on enthymemes to make arguments: it seems
to be part of human nature. It is, therefore, important to scrutinize them
carefully in order to avoid making unsubstantiated claims.
that we argue either by using enthymemes or by using examples. Whereas
enthymemes are deductive forms of argument, examples are inductive; that
is, they are based on particular instances. If someone says, "That small,
green apple is likely to taste sour," she is probably basing the claim on
inductive reasoning which relies on several instances of having tasted
green apples. In the same way, if you claim the sun will come up tomorrow,
your argument is based on many instances in which you have observed the
Examples are especially useful in arguments that attempt to establish
something about the future. We know what is likely to happen in the future
because we compare it with the past. When we draw an example from the
past, we often call it a precedent, an instance from the past which is
very similar to the one being considered.
If a king wants permission to hire a body guard (an example used by
Aristotle), someone might argue that he is trying to become a tyrant in
King James is trying to become a tyrant because he wants
permission to hire a body guard. We know that when Alfred hired a body
guard, he was preparing to take more power to himself. This is the same
situation. Therefore, we should not allow King James to hire a body
guard.We use examples all the time to argue about the future.
Should we allow a mall to be built in town? Some would say no because in
other towns, malls have caused the down town area to fold up. Should we
get involved in an internal conflict in another nation? Some would argue
no and liken the situation to Vietnam; others would argue yes by comparing
the situation to the 1930s when Hitler was allowed to rise to power
because of policies of non-involvement.
You have to be careful when you use examples as arguments because they
are easily rebutted. Someone can always claim that the present situation
is not like the one you have invoked. You need to be ready to show
specific lines of comparison and to show that they are significant.