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Critical Thinking
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  1. Critical Thinking

  2. Critical thinkers use reasons to back up their claims. • What is a claim? • A claim is a statement that is either true or false. It must ALWAYS have a truth value (although we do not always have to know if it is true or false). Here are some examples of claims: • It is 5 p.m. • It ought to be easier to register for classes at this university. • 2 + 2 =4 • There is ice on the moon. • There isn’t ice on the moon.

  3. Truth or falsity do not apply to questions, commands, or exclamations. Hence, they are not claims. • Wow! • Will you please close the door? • Keep your eyes on your own paper. • These are not claims.

  4. Arguments • An argument =df. An attempt to support a claim representing a certain position on an issue by providing other claims that serve as a reason or reasons for believing it. • The conclusion (of an argument) = df. The claim (position on an issue) one is attempting to support, or the claim for which one is arguing. • The premises (of an argument) = df. The claims that serve as reasons for believing the conclusion.

  5. Arguments • Thus an argument is a set of claims that involves the relations of claims to one another. • The relations between an argument’s claims are that the premises support the conclusion or that the conclusion follows from the premises. • The recognition, construction, evaluation, and, where necessary, criticism of arguments is a crucial part of critical thinking.

  6. What arguments are not • In critical thinking, an argument is not about two people having a feud or disagreeing about something. Arguments, in the critical thinking sense, do not even need two people.

  7. Misconceptions about Arguments “Arguments are attempts to persuade” • While arguments may be used for this purpose not all arguments attempt to persuade and not all attempts to persuade are arguments. • The better view is that arguments are attempts to prove or establish or support some claim. • “Arguments are attempts to explain.” • Arguments and explanations do have a superficial resemblance but their purposes are different. • An argument attempts to establish that some claim is true whereas an explanation attempts to specify either how something works or what caused or brought it about.

  8. Two kinds of good arguments • Philosophers traditionally classify arguments as either deductive or inductive. • The difference between a deductive and an inductive argument is the difference in the sort of claim made for the argument. • If the arguer alleges that the premises are conclusive evidence for the conclusion, then the argument is deductive; if the assertion is that they support the conclusion but don’t guarantee it, then the argument is inductive. • Deductive arguments are either valid or invalid.

  9. Two kinds of good arguments • To say that a deductive argument is valid is to say that it is not possible for its conclusion to be false if its premises are true. Thus we define validity as follows: A deductive argument is valid when, if its premises are true, its conclusion must be true. • Every deductive argument makes the claim that its premises guarantee the truth of its conclusion, but not all deductive arguments live up to that claim. Deductive arguments that fail to do so are invalid. • An example of a valid argument: • P1:f you get 90% or above in this class, then you will get an A in the class. P2: You got 90% in this class. Conclusion: Therefore you will get an A in the class.

  10. Two kinds of good arguments • Inductive arguments are those in which the premises are intended to provide support, but not conclusive evidence, for the conclusion. • Inductive arguments are not valid or invalid. Inductive arguments are weak or strong. • An inductive argument is strong when its premises provide evidence that its conclusion is more likely true than false. An inductive argument is weak when its premises do not provide evidence that its conclusion is more likely true than false. • Paying off terrorists in exchange for hostages is not a wise policy, since such action will only lead them to take more hostages in the future. This is an inductive argument.

  11. Implied Premises and Conclusions • Page 50 of the text: • “The use of condoms is completely unnatural. They have been manufactured for the explicit purpose of interfering in the natural process of procreation. Therefore, the use of condoms should be banned.”

  12. Recognizing arguments • As we already said, an argument, whether deductive or inductive, has two parts, and one part is the reason for believing that the other part is true. Sometimes there are indicators to help us figure out which part is which. Unfortunately, indicators are not always used. However, it is very helpful to understand the language of arguments.

  13. Conclusion Indicators • A few examples of conclusion indicators: Therefore • Thus • Hence • So • Consequently

  14. Premise indicators • A few examples of premise: • Since • For • Because • Given

  15. Examples • Newton was an abstract thinker because all scientists are abstract thinkers and Newton certainly was a scientist • What is the conclusion? What are the premises? • Every officer on the force has been certified, and nobody can be certified without scoring above 70 percent on the firing range. Therefore every officer on the force must have scored above 70 percent on the firing range. • What is the conclusion what are the premises?

  16. Other terms and concepts • Truth – • What is truth? • In philosophy, there are very many theories of truth. If you take an introduction to philosophy course, for example, you will probably learn about coherence theories of truth, correspondence theories of truth, pragmatic theories of truth, and so on. • We are taking a basic approach to truth in this class. Truth and falsity are the properties of claims, and, generally speaking, a claim has whichever property it has, regardless of what we think about this. The claim is true if it corresponds with reality, basically.

  17. Other terms and concepts • What is knowledge? • David L. Fairchild said, ““This claim may be less extreme than it first appears, Part of what is at issue here involves a distinction between appropriate and inappropriate ways of using “know.” We sometimes claim to “know” things that we only believe, for example, or things that we wish we knew or that we would like someone else to stop talking about. Sometimes we use “know” deliberately, to preclude further discussion of a topic about which we are unsure of or with which we are uncomfortable. If becoming better reasoners entails becoming more precise in our epistemological vocabulary, we may well claim the result of “knowing” less after the experience than we did before. “

  18. Other Terms and Concepts • For the purpose of this class, we will say that you can have knowledge of the truth of a claim if (1) You have a belief (2) You have justification for this belief in the form of an argument beyond a reasonable doubt (3) You have no reason to expect that you are mistaken.

  19. Other Terms and Concepts • Value judgments – What are value judgments? • What is the difference between a difference in values and a difference between tastes or preferences? • How can critical thinking be related to value judgments?

  20. fallacies • Begging the question • Equivocation • Appeal to authority • Appeal to emotion • Slippery slope • Faulty analogy • Appeal to ignorance • Straw man • Ad hominem – personal, circumstantial, tu quoque