Revisiting the Toulmin Model and its Greek Predecessors Errors in Reasoning: Revisiting the Toulmin Model and its Greek Predecessors

The Core Concepts To detect errors in argumentation… Ask probing questions that politely but relentlessly demand… Logical Consistency Corroborated Evidence

A Corny Ode to Toulmin: “The Model Model” Deliberately designed With these core concepts in mind, To be as error free As any argument can be With data and warrants and qualifiers, too It seems the perfect argument For me and for you

Self-Checks in Picture Form

Self-Checks in Words The Data generates the Claim. The Backing justifies the Warrant, which justifies the Claim. The conditions of Rebuttal determine the Qualifier, realistically limiting the scope of the Claim.

However, one can still ask… Does the data prove the claim? Does the qualifier sufficiently limit the claim? Does the warrant justify the claim? Is there a better warrant to justify the claim? Does the backing justify the warrant?

And what about that data? Is it directly relevant to the claim? Is it sufficient to prove the claim? Are its sources trustworthy? Are its methodologies reliable? Is it up-to-date?

Any answer that is a no… does not necessarily invalidate the entire argument, though it may does indicate an error in reasoning, which may slightly, moderately, or severely weaken the argument, depending on the severity of the error

What about the Greeks? Deduction Induction Major Premise Minor Premise Conclusion Induction Generalization Cause-Effect Analogy

More Internal Self-Checks to Ward off Errors and Weaknesses Toulmin vs. Aristotle More Internal Self-Checks to Ward off Errors and Weaknesses More External Checks to Analyze Logic and Find Weaknesses

External Checks Deduction Induction Is the argument valid? Is the argument sound? Because deduction is a conclusive form of reasoning, the tests are likewise conclusive (i.e. either valid or invalid). Induction Is the argument strong? Is the argument cogent? Because induction is based on probable outcomes, the results of the tests are not absolute but differ in degree.

Evaluating Deductive Arguments I A deductive argument is valid if the conclusion follows from the premises regardless of the truth of the premises or conclusion. All cheetahs have purple eyes. Frita is a cheetah. Therefore, Frita has purple eyes.

Evaluating Deductive Arguments II A deductive argument is invalid if the conclusion does not follow from the premises regardless of the truth of the premises or conclusion. If Alexander Hamilton died of heart disease, then Hamilton is dead today. Hamilton is dead. Therefore, Hamilton died of heart disease.

Evaluating Deductive Arguments III A deductive argument is sound if it is valid and all of the premises are true. All men are mortal. Socrates was a man. Therefore, Socrates was mortal.

Evaluating Deductive Arguments IV A deductive argument is unsound if any part of it is false regardless of whether or not the argument is valid. The doctor is a groundhog. All groundhogs are mortal. Therefore, the doctor is mortal.

More Practice with Deduction All bears eat oysters. 2. All bears have fur. Julian is a bear. Julian is a bear. Therefore, Julian eats oysters. Therefore, Julian has fur. All people are mortal. 4. The fridge always cooks Julian (the bear) is mortal. meat. Therefore, Julian is a person. The chicken is in the fridge. Therefore, the chicken is cooking.

Answers 1. valid, unsound 2. valid, sound 3. invalid, unsound 4. valid, unsound

Evaluating Inductive Arguments I An inductive argument is strong if the conclusion is probably true (50% chance or higher) regardless of whether or not the premises are true . Most boys like to play sports. Britney Spears is a boy. Therefore, Britney probably likes to play sports. (Example from www.blinn.edu/brazos/.../Types%20of%20Arguments.ppt‎)

Evaluating Inductive Arguments II An inductive argument is weak if the conclusion is probably false (50% chance or higher) regardless of whether or not the premises are true. Grass is green. Spinach is green. Spinach and grass probably taste the same. (Example from Shabo, Magedah. Rhetoric, Logic, and Argumentation: A Guide for Student Writers. Prestwick, 2010.)

Evaluating Inductive Arguments III An inductive argument is cogent if the premises are true and the conclusion is probably true (50% chance or higher). Most recording artists have talent. Britney Spears is a recording artist. Therefore, Britney probably has talent. (Example from www.blinn.edu/brazos/.../Types%20of%20Arguments.ppt‎)

Evaluating Inductive Arguments IV An inductive argument cannot be cogent unless the premises are true and the conclusion is probably true (50% chance or higher); otherwise, it is uncogent (or not cogent). The average human body temp. is 55 deg. F. My current temperature is 102 deg. F. I probably have a fever. (Example from Shabo, Magedah. Rhetoric, Logic, and Argumentation: A Guide for Student Writers. Prestwick, 2010.)

More Practice with Induction This jar contains 30 pieces of candy. 25 randomly selected pieces are M&Ms. Probably, all the pieces are M&Ms. 3. The constellations are frozen humans and animals. The sun is hot. The sun could melt the constellations. 2. This jar contains 30 pieces of candy. 5 randomly selected pieces are M&Ms. Probably, all the pieces are M&Ms. Most pumpkins are orange. Most oranges are orange. Pumpkins taste like oranges.

Answers 1. strong, cogent 2. weak, uncogent 3. strong, uncogent 4. weak, uncogent

A Range of Imperfections As should be clear by now, arguments can be flawed or imperfect in a number of ways, depending on the type of argument: Toulmin Weak Links between Parts Weaknesses in the Data Deduction Invalidity, Unsoundness Induction Weakness, Un-cogency

Worse than Weak outrageous errors in argumentation Somewhat ironically, the most outrageous errors in argumentation (yet to be studied in this course) recur so frequently they have each been given their own name. Collectively, they are called the logical fallacies.

Not Every Weakness is a Fallacy For example, An analogy (the third type of induction) would be considered weak if less than 50% of the analogy applied to the argument. An analogy would have to be extremely weak to be classified as a fallacy of a false analogy.

On the Other Hand… Sometimes a mistake is almost always classified as a fallacy. For example, flaws in linking causes and effects (the second type of induction) would almost always be categorized as the fallacy of correlation versus causation. Most of the time, however, there is a wide range of imperfection, all the way from minor flaw to full- blown fallacy.

Much more to come on fallacies in Lesson 8! Preview Much more to come on fallacies in Lesson 8!

A Review of Ranges a range of intentionality, all the way from In addition to a range of errors, there is also a range of intentionality, all the way from absolutely unintentional to entirely deliberate. There are just so many ways for human beings to be imperfect.

A “Philosophy” of Flaws Thus, as the saying goes, “To err is human, to forgive divine.” Or should we say: as it is human to err, it is thus critical to critique—our entire focus in this unit!