by Professor Keefer
First of all, we must be able to distinguish arguments/propositions/claims from other sentences such as questions (Are suicide bombers ever afraid to die?), proposals (Letıs kill them.), suggestions (We recommend that you workout every day.), commands (Donıt shop at Shoprite.), and exclamations (The Middle East is a bloodbath!) An argument is a group of statements, one or more of which (the premises) are claimed to provide support for, or reasons to believe, one of the others (the conclusion.) So warnings, statements of belief or opinion, loosely associated statements, reports, expository passages, illustrations, conditional statements and explanations are not arguments by themselves although they may lead to arguments. For example, a conditional statement can form the major premise of a conditional or hypothetical syllogism, but it is not an argument on its own. "If cigarette companies publish warning labels, then smokers assume the risk of smoking. Cigarette companies do publish warning labels. Therefore, smokers assume the risk of smoking. "To find out if we really have an argument we should 1) rule out typical kinds of non-arguments, 2) examine indicators such as therefore, it follows that, because, since etc. and 3) most importantly, the presence of an inferential relationship between the statements. The purpose of logic is to allow us to develop methods and techniques to distinguish good arguments from bad. Here is an example: All crimes are violations of the law. Rape is a crime. Therefore rape is a violation of the law. Symbolically, it is stated as A equals B. C equals A. Therefore C equals B. But the following is bad: Some crimes are misdemeanors. Rape is a crime. Therefore rape is a misdemeanor. This is a valid form: All A are B. All B are C. Therefore, all A are C. This is invalid: All A are B. All C are B. Therefore all A are C. For example: All cats are animals. All dogs are animals. Therefore, all cats are dogs. Remember this again when we go into testing soundness of deductive arguments.
You must be able to distinguish premises or claimed evidence (Toulminıs data or grounds) from conclusion or what is claimed to follow from the evidence. An inference is the reasoning expressed in an argument. Some arguments have more than one conclusion or more than two premises and can be described syllogistically, horizontally, vertically, in clusters, symbolically as alphabetical letters or Venn diagrams. Once we have clearly recognized the argument, it is then important to categorize it into induction or deduction. While some people often generalize and say deduction moves from general to specific, and induction from specific to general, this is not always true.
A deductive argument is one in which the premises are claimed to support the conclusion in such a way that if they are assumed true, it is impossible for the conclusion to be false, so that the conclusion follows by necessity. An inductive argument is an argument in which the premises are claimed to support the conclusion in such a way that if they are assumed true, it is improbable that the conclusion is false. Five examples of arguments that are typically deductive are arguments based on math, arguments from definition, and categorical, hypothetical or conditional, and disjunctive syllogisms. Pure math is deductive but statistics are inductive. Toulminıs method is largely inductive because his system is a rebellion against the rigors of formal logic and his 6 part chain includes a qualifier.
A categorical syllogism is a syllogism in which each statement begins with one of the wordsall, no, or some. "All cats are animals. Some cats are black and white. Therefore some animals are black and white." Or use the famous Socrates syllogism"All men are mortal. Socrates is a man. Therefore Socrates is mortal." Socrates falls into the "some" category. A categorical syllogism relates two classes or categories, denoted respectively by the subject term and predicate term, and the proposition asserts that either all or part of the class denoted by the subject term is included in or excluded from the class denoted by the predicate term. We have four forms: All S are P. No S are P. Some S are P. Some S are not P. A hypothetical or conditional syllogism is a syllogism having a conditional statement for one or both premises. A disjunctive syllogism is a syllogism having a disjunctive statement for one of its premises: "Either you are with the terrorists or you are with the US and its allies. You are not with the US and its allies. Therefore you must be with the terrorists." Then try to construct a conditional syllogism to determine how such rogue states might be punished. In everyday conversation it is hard to always detect the purity of syllogistic argument. An enthymeme is an argument missing a premise or conclusion, but usually the missing element is implied. "The corporate income tax should be abolished; it encourages waste and high prices." The missing element is whatever encourages waste and high prices.
In general, inductive arguments are such that the content of the conclusion is in some way intended to "go beyond" the content of the premises. Inductive arguments include predictions about the future, arguments from analogy, inductive generalizations, (because some beans from the bag are chocolate, it is likely they are all chocolate,) arguments from authority (he could be stupid or misinformed in spite of his rep!), argument based on signs (or coexistential as the CT text says), and causal inference which isnıt exactly the same as a conditional statement or hypothetical or conditional syllogism. In science, the discovery of a law of nature is generally considered to be inductive, while its application is deductive, proceeding from a true, valid premise.
Once we categorize arguments, we must then analyze them. We need to look at two things: the claim that evidence exists, and what kind of evidence that is, and the claim that the alleged evidence actually supports that claim. Deductive arguments are analyzed as valid or invalid, sound, or unsound. To test the validity of an argument, we must examine whether the premises support the conclusion in such away that if they are assumed true, it is impossible for the conclusion to be false. Here is an example of an invalid argument having true premises and a true conclusion: "All banks are financial organizations. Wells Fargo is a financial organization. Therefore, Wells Fargo is a bank." Any deductive argument having true premises and a false conclusion is obviously invalid. But you can have a valid argument that is unsound such as: "All wines are soft drinks. Ginger ale is a wine. Therefore ginger ale is a soft drink."
A sound argument is a deductive argument that is valid and has all true premises.
Inductive arguments are evaluated as weak/strong or cogent/uncogent. Thus, a strong inductive argument is: "This barrel contains one hundred apples. 80 apples selected at random were found to be ripe. Therefore, probably all one hundred apples are ripe." A weaker version is as follows: "This barrel contains one hundred apples. Three apples selected at random were found to be ripe. Therefore, probably all one hundred apples are ripe." Hence, strength and weakness, unlike validity and soundness, relate to degrees. A cogent argument is an inductive argument that is strong and has all true premises, the inductive analogue of a sound deductive argument. Classically it is without qualification, but Toulmin added a qualifier to his reasoning chain. However for classical cogency, the premises must not only be true but also not overlook some important factor that outweighs the given evidence and requires a different conclusion.
When you are debating in a rush, keep asking these two questions: Do the premises (data, grounds) support the conclusion (claim)? Are all the premises true? As you write research papers or debate you will develop extended arguments such as: "American Doctors who attend elderly people in nursing homes in NY State in 2002 often prescribe tranquilizers to keep these people immobile. This practice is often unwarranted, and it often impairs the health of the patients. These tranquilizers often have damaging side effects in that they accentuate the symptoms of senility, and they increase the likelihood of a dangerous fall because they produce unsteadiness in walking. Furthermore, since these medications produce immobility, they increase the risk of bedsores. Doctors at the Center for Aging and Health say that physicians who care for the elderly are simply prescribing too much medication."
Often we get snowed under in our evidence and we drown instead of resurfacing to test the premises or data and use it to back up our claim or proposition.
To review: The Toulmin modeldata, warrant, backing, qualifier, reservation and claimis more flexible and field dependent than formal logic but there are some similarities. The data function like evidence and premises on which the argument is based. The claim is the conclusion. The warrant states the reasoning used to move from the data to the claim, and it functions like an inference. The backing consists of facts or information used to support the inference made in the warrant. The qualifier modifies the claim and indicates the rational strength the arguer attributes to it. The reservation states circumstances or conditions in which the claim would not be true. The Toulmin model often presents difficulties such as misidentifying unstated warrants, confusing the data and the warrant, confusing data and backing, and applying incorrect standards to diagrams of complex and subtle arguments.