Reasoning and Problem Solving Lecture 1 What is Critical Reasoning?

1. Reasoning and Problem SolvingLecture 1What is Critical Reasoning? By David Kelsey

2. Getting Started • The course syllabus. • Things to consider: • Contact information • Course requirements • The lecture schedule

3. Course Objectives • Thinking Rationally: We will learn how to think correctly or rationally or logically. • For someone to think rationally just means that she, from her set of beliefs, makes inferences that are justified given the laws of logic. • The laws of logic: And we will learn the laws of logic so that we know just which inferences are justified.

4. The Laws of Logic • The laws of logic: dictate just which inferences we can make. • They are rules for making good inferences. • 2 examples: • Modus Ponens: • Modus Tollens: • Sentence letters: We use Capitalized letters like ‘P’ and ‘Q’ to stand for sentences.

5. An inference: a statement that follows from one or more other statements. The Verb To infer something The noun The inference made Inferences

6. Statements • A statement is a proposition. • Sentences and Propositions: • Just like words have meanings, sentences have meanings.

7. Propositions • The form of a proposition: • ‘it is the case that…’. • Propositions are true or false.

8. Propositions & Sentences • A sentence does two different things: it both expresses a proposition and asserts a proposition. • The expressed proposition: • the literal meaning of the words of that sentence.

9. Expressing a proposition • For a sentence to express a proposition: • is for that sentence to toss the proposition up in the air, so to speak. • It is to put the proposition up for usage. • Knowing what proposition a sentence expresses is often quite easy.

10. The asserted Proposition • Making use of a proposition: • Just how a sentence makes use of the proposition a sentence expresses determines it’s actual or intended meaning. • The actual or intended meaning of a sentence: • What the speaker or writer of the sentence means when she writes or says it.

11. Asserting a proposition #2 • Assertion: • The actual or intended meaning of a sentence is what is asserted by the words of the sentence. • Declaration: • For a sentence to assert a proposition is simply for the sentence to declare of the proposition that it is the case.

12. Sarcasm • Other kinds of sentences: • Sarcasm: • The messy roomate: • “She always takes out the trash”. • This sentence expresses: • But the sentence asserts:

13. The laws of logic • The laws of logic: are rules for making a correct inference P given a certain set of propositions Q1-n. • Socrates example • Arguments: when one proposition is inferred from one or more other propositions • Other definitions of an Argument

14. Arguments • Argument: a position supported by reasons for its truth. • To take a position: • taking a side or stand on an issue. • An issue: what is raised when one considers whether or not a proposition is true. • There are always 2 sides to an issue

15. Issues • Issues: • we might go as far as to say that an issue just is a question. • Intelligent life: • Safety belt law: • Mac vs. Pc:

16. Arguments & Positions • Arguments & Positions: so when we take a position on an issue and support it with reasons we have given an argument. • Intelligent life: • Safety Belt law: • Mac vs. Pc:

17. Conclusions &Premises • Arguments: • The conclusion of an argument: • The premises of an argument: • Examples: • Socrates again • Raining and Pouring

18. What an argument isn’t • What an argument isn’t: Let us be a bit clearer about what an argument is by stating what it isn’t. • Not a Fight: • Not Persuasion: • Advertisement example:

19. Persuasion • Persuasion vs. Argument: • An argument offers support for some claim, its conclusion. • Persuasion needn’t offer any support for a point. • Not Logic: It merely attempts to get you to believe a point. • This attempt needn’t be one through logic though. • Persuasion through rhetoric: • Rhetoric: is “a broad category of linguistic techniques people use when their primary objective is to influence beliefs and attitudes and behavior”

20. Arguments vs.Explanations • Arguments vs. Explanations: • Explanation of X: If one gives an explanation about some thing X, one gives some details about X with the hope of coming to better understand X. • Example: fixing a flat tire

21. Recognizing Arguments • Conclusion Indicators: find the conclusion of an argument by looking for conclusion indicators. • Examples of Conclusion Indicators: therefore, hence, and others • Premise Indicators: find the premises of an argument by looking for premise indicators • Examples of Premise Indicators: because, since, and others

22. An introduction to formalizing an argument • Challenging an argument: • In challenging an argument you must first formalize it. • Formalizing an argument: • Is the reconstruction of that argument in its most simplified form. • Read the passage • Write down the argument’s propositions

23. Explicit Premises • Explicit premises: • asserted by the words of the text. • Simplifying the premises:

24. Implicit Premises • Implicit or unstated premises: entailed by the words of the text. • P entails Q: • PQ • Bloodhound example:

25. Factual claims • Arguments and Claims: • Factual Claims • Either true or false. • Established methods • Generally Established Criteria • Settling Disagreement • Example: Water is H2O

26. Non-factual claims • Non-factual claims: • No established methods • Can’t settle Disagreement • Some examples:

27. Value Claims • Value claims:non-factual claims that assert that some moral property is instantiated in some object or action or event. • Properties and Moral Properties • Why worry about factual & Non-factual claims: • Never Ought from Is: