linesofreasoning.txt

Creating a Logical Line of Reasoning
To create a persuasive line of reasoning that readers can follow, we must understand the natural instincts of humanity. Aristotle
suggests we rely on prepared ways of thinking through argumentative topics to create recognizable lines of thought. This type of
preparation asks students to develop their argument in general, recognizable lines of thinking, which are often referred to by
rhetoricians as ​Aristotle’s Common Topics​: ​1. Definition 2. Comparison 3. Relationship 4. Circumstance 5. Testimony
1. ​Definition​—Lines of Reasoning
❏ Definitions can limit the subject argued to a certain class of things (genus). In other words, the subject is defined by the
limits fixed on the term. (Ex. Socrates uses this strategy to defend himself against the charge that he is an atheist. Socrates
questions what is meant by the term “divine” and then proposes a definition that supports his view).
❏ Definitions can divide the terms of the argument into parts to clarify the concepts. This strategy of division can also serve as
an organizing principle for the argument. (Ex. “There are four classes of idols which beset men’s minds. To these for
distinction’s sake I have assigned names, call the first class Idols of the Tribe; the second, Idols of the Cave; the third, Idols
of the Marketplace; the fourth, Idols of the Theatre.”—Francis Bacon ​Novum Organum,​ 1620).
2. ​Comparison​—Lines of Reasoning
❏ Similarity​ is a basic principle of many arguments because of the human tendency to measure one thing against another
and to rely on the familiar to better understand the unfamiliar. Therefore, analogical arguments argue that if two things are
alike in one or two characteristics, they are probably alike in another characteristic.
○ A 1 2 3 4→5
B 1 2 3 4 → (5)
A and B resemble one another in 4 known, confirmable respects. This logical line of reasoning can develop from
these knowable points of resemblance (similarities) creating the leap that 5 (being known in A) can probably be
true for B, achieving probability, even though it is not certain.
❏ Degrees​ of similarity or difference (more and less) helps to advance arguments for one thing as better than another or
worse. These arguments require a value judgment and are subjected to several human tendencies (see criteria below).
○ Criteria​: A greater number of things can be considered more desirable than a smaller number of the same things
(numerical superiority). Ex. A congressional legislator may argue that a tax bill which will bring in 4 billion dollars of
revenue is a better proposal than the tax bill that will bring in 3 billion dollars.
○ Criteria​: That which is an end is a greater good than that which is only a means. A means is desirable only for the
sake of something else, and an end is desirable for its own sake. Ex. Health is a greater good than exercise because
we indulge in exercise for the sake of acquiring or maintaining health.
○ Criteria​: What is scarce is greater than what is abundant. This principle is the basis of most monetary systems. Gold
is more valuable than silver because gold is more scarce.
○ Criteria​: What people of practical wisdom would choose is a greater good than what ignorant people would
choose. This type of argument relies on authority, experts, and informed opinion over that of lay people or the
masses.
○ Criteria​: What the majority of people would choose is better than what the minority would choose. This line of
thought is the opposite of the previous one for determining worth. Ex. Best Sellers lists and elections—the best
candidate is the one people elect. Advertisers also rely on this line of thinking. What all people desire must be
good. Advertisements often provide evidence that most people buy a product, which makes that product the best
product due to the popularity of the product.
○ Criteria​: What people would really like to possess is a greater good than what people would merely like to give the
impression of possessing. Ex. In ​The Prince​, Machiavelli said that a reputation for virtue was so important to the
image of a ruler that even if the ruler was not virtuous, the ruler must appear to be virtuous. This view suggests
that power is a greater good than virtue because power is what the ruler really wants and to get power, the ruler
must assume a mask of virtue.
○ Criteria​: If a thing does not exist where it is more likely to exist, it will not exist where it is less likely to exist. This
line of thinking creates force about what is probable, but does not create certainty. Ex. If a man would steal from a
friend, he would steal from a stranger.
Modified by Tara Seale from ​Classical Rhetoric for the Modern Student​ Edward P.J. Corbett

3. ​Relationship​—Lines of Reasoning
❏ Cause and Effect​ speaks to the curiosity of human nature to discover the “why” of something. In this case, arguments
recognize an effect and then consider the causes. It is important that these lines of thinking do not presume a relationship
and instead provide evidence of a relationship. Ex. Before Jonas Salk won approval to put his polio vaccine on the market,
he had to present ample and sufficient evidence that the vaccine would prevent polio and contribute to the public welfare.
This example would need a high degree of certainty because of the scientific nature. Yet, we often argue causally tracing an
effect to a probable cause to create a high degree of probability, which is not the same as a high degree of certainty.
❏ Antecedent and Consequence​ pursues a line of thinking that claims when given a certain situation what will follow is a
particular consequence. Ex. If this person is a citizen (situation/antecedent), then this person has the right to vote
(consequence).
❏ Contraries​ involve opposite or incompatible things of the same kind (Ex. Liberty and Slavery). To create a line of reasoning
for these types of arguments, Aristotle provides this example: “Self-control is beneficial because licentiousness is harmful.”
The subject terms “self-control” and “licentiousness” are contraries and the descriptors “beneficial” and “harmful” are
contraries. The argument advances when we describe the relationship in terms of a contrary relationship.
❏ Contradictions​ are built on the principle that a thing cannot at the same time and in the same respect be and not be. Ex. If
one group of experts claims that climate change is damaging to the environment and another group of experts claims that
climate change is not damaging, we can see that these claims contradict and cannot both be correct. Student writers can
benefit by recognizing contradictions to situate the argument in terms of the contradictory propositions. “Some say…
others say... “ can set up an either/or alternative to clarify two incompatible positions, but this line of thinking often leads
to false dichotomies that too narrowly limit the viewpoints.
4. ​Circumstances​—Lines of Reasoning
❏ Possible and Impossible ​involves proposing that a course of action is possible and/or discouraging another course of
action as impossible.
○ Criteria​: If one pair of contraries is possible, then the other is possible too. Ex. If you fall sick, you can get well.
○ Criteria​: If one of a pair of similar things is possible, the other thing is possible too. Ex. If a person can play a piano,
it is possible they can play an organ.
○ Criteria​: If the more difficult of two things is possible, then the easier is possible too.
○ Criteria​: If something can have a beginning it can have an end, and inversely, if something can have an end, it can
have a beginning.
○ Criteria​: If the parts of a thing are possible, then the whole is possible, and conversely, if the whole is possible, the
parts are possible.
○ Criteria​: If a thing can be produced without art or preparation, it certainly can be done with the help of art or
planning.
❏ Past fact and future fact​ ​often requires support, evidence, or argument to establish a past fact.
○ Criteria​: If the less probable of two events has occurred, the more probable event is likely to have occurred too. Ex.
If, as has been admitted, this man has been guilty of stealing from his father, do you find it too far-fetched to
believe he was capable of embezzling from his employer?”
○ Criteria​: If something that naturally follows something else has occurred, then that something else has happened
too, and conversely, if the antecedents were present then the natural consequences occurred too. Ex. If we hear
thunder, we presume lightning flashed, even if we did not see it.
○ Criteria​: If someone had the power and the desire and the opportunity to do something, then he or she has done
it. This argument assumes people will gratify their desires when they have the chance.
○ Criteria​: If the power and the desire to do something are present, then that something will be done. Ex. Pacificists
argue that the mere possession of atomic weapons poses a constant temptation to use those weapons.
○ Criteria​: If the antecedents of something are present, then the natural consequences will occur. Ex. If a raging mob
gathers, violence will follow.
○ Criteria​: If the means are available, the end will be accomplished. Ex. The team with the best players will win.

Modified by Tara Seale from ​Classical Rhetoric for the Modern Student​ Edward P.J. Corbett

5. ​Testimony​—Lines of Reasoning
❏ Authority​ carries less weight than it once did because we live in an Information Age and people are not as disposed to be
swayed by the voice of authority and are less likely to accept something as true merely because someone claims it is true.
Yet, informed opinion is still a persuasive force. No one person can claim knowledge on all things, so we often rely on the
studies and research of specialized experts.
❏ Testimonials​ often take the form of letters of recommendations, character witnesses, opinion polls, audience ratings, and
best seller lists. Supporting an argument with this strategy can be successful in certain circumstances, but could also be
viewed as vulnerable to counterarguments.
❏ Statistics​ provides persuasive support for arguments, but statistics have limitations and should not always be accepted
uncritically. Pollsters, for example, often assume that people always know their own mind on questions put to them and
that people will give truthful answers.
❏ Maxims​ are precepts, proverbs, famous sayings, self-evident truths, and other charismatic statements that are helpful in
creating persuasive arguments. Yet, relying too much on maxims or repeating maxims without forethought or additional
commentary can be viewed as lazy and simplistic.
❏ Laws​, statutes, contracts, testaments, records, and primary documents (recorded evidence) is a compelling force in
arguments. But we must also realize that recorded words are also open to challenge and interpretation.
❏ Precedent​ (Examples) refers to what has happened before. Examples that came before often set precedents that guide the
present, like judicial decisions.

Modified by Tara Seale from ​Classical Rhetoric for the Modern Student​ Edward P.J. Corbett