Writing Analytically, 6th Edition - Rosenwasser, David & Stephen, Jill [128]
Probably the most common way of talking about logical argumentation goes back to Aristotle. This approach doesn’t always have direct applications in the kinds of analytical writing described in this book, but knowing the ways that philosophers have devised for evaluating arguments can expand your ability to assess your own and others’ reasoning about claims and evidence.
There are a number of rules for evaluating the validity of a syllogism’s conclusion. In this short section, we cannot offer enough of the details about argument analysis to equip you with the necessary skills. But we will give you enough detail so that you can understand the basic principles and methods of this way of thinking about argument.
At the heart of the Aristotelian model is the syllogism, which consists of three parts:
Major premise: a general proposition presumed to be true;
Minor premise: a subordinate proposition also presumed to be true; and
Conclusion: a claim that follows logically from the two premises, if the argument has been properly framed.
Here is a frequently cited example of a syllogism:
All men are mortal (major premise).
Socrates is a man (minor premise).
Therefore, Socrates is mortal (conclusion).
A premise is a proposition (assumption) upon which an argument is based and from which a conclusion is drawn. In the syllogism, if both of the premises have been stated in the proper form (both containing a shared term), then the conclusion must be valid.
An important thing to know about syllogisms is that they are only as true as the premises they are made of. It is not, however, the business of the syllogism to test the truth of the premises. Syllogisms can only demonstrate that the form of the argument is valid. As you will see, this word “valid” is a key term in argument evaluation, a term that does not mean the same thing as right or true.
If a writer follows the prescribed steps of the syllogism without violating any of the rules on proper wording and on the way the steps may be put together, then the conclusion arrived at in step 3 is valid. An argument evaluated in this way can be valid and still be false. For example:
All politicians are corrupt.
The mayor of Chicago is a politician.
Therefore, the mayor of Chicago is corrupt.
The problem here is not with the form of the syllogism but with the fact that the major premise is untrue.
To make good use of syllogistic reasoning, you need to get into the habit of recasting arguments that you write or read or hear into the proper syllogistic form. The way most people articulate claims—often without even recognizing that they are making claims—is rarely if ever syllogistic. Claims, for example, if they are to be most easily assessed for validity, usually need to be recast using forms of “to be” rather than other kinds of verbs (as in the Chicago example above).
While arguments as formulated in formal logic are grounded in abstract, universal terms, most arguments as we encounter them in daily life involve statements about values and beliefs. These real-life arguments typically appear in a form that philosophers call the “enthymeme.” An enthymeme is an incomplete syllogism. One of its premises has been left unstated, usually because the person offering the argument takes the unstated assumption to be a given, something so obviously true that it doesn’t even need to be made explicit.
Sample Enthymeme: Cats make better pets than dogs because cats are more independent.
Unstated Assumption: Independent animals make better pets.
Sample Enthymeme: Charter schools will improve the quality of education because they encourage competition.
Unstated Assumption: Competition improves the quality of education.
TOULMIN’S ALTERNATIVE MODEL OF THE SYLLOGISM
British philosopher Steven Toulmin offered a competing