PHIL2642 CRITICAL THINKING USYD NOTES PART 1: LECTURE NOTES LECTURE CONTENTS LECTURE 1: CLAIMS, EXPLAINATIONS AND ARGUMENTS LECTURE 2: CONDITIONS AND DEDUCTION LECTURE 3: MORE DEDUCTION LECTURE 4: MEANING AND DEFINITION LECTURE 5: BEGGING THE QUESTION LECTURE 6: GENERALISATIONS, SAMPLES & SURVEYING LECTURE 7: ABDUCTION AND EXPLAINATIONS LECTURE 8: CAUSAL ARGUMENTS WEEK 9: SCIENCE, PSEUDO-SCIENCE AND NON-SCIENCE WEEK 10: PROBLEMS WITH STATISTICS LECTURE 11: ANALOGIES AND FALLACIES LECTURE 12: FALLACIES CONT. PART 2: TUTORIAL NOTES
PHIL Critical Thinking Page 2 Lecture 1 - Part 2 Wednesday, 1 August 2012 9:43 AM Claims, Explanations and Arguments Explanations Consist of the thing or things that need explaining (the explanandum or (plural) explananda) and the thing that does the explaining (the explanans) (Mnemonic ANSWER) The explanans makes sense of the explanandum. Not an argument because the claims are not rationally connected in the way that characterises arguments. Neither claim is supposed to give us a reason to believe that the other claim is true. Connects two things that you make already believe. Example Athens hosted the first Modern Olympics in 1896, because it was the capital of the nation that hosed the Ancient Olympics; Namely Greece. --> Explanation Athens hosted the first Modern Olympics in 1986. I read a book about the Olympics which said that Athens was the host city --> Argument What happens when someone doesn't accept the explanandum? - You have to provide an argument to convince them. Could be in the test Give a brief argument for the conclusion that the earth's atmosphere is warming. Give a brief explanation for the fact that earth's atmosphere is warming. Give a brief argument for the conclusion that exposer to radiation causes cancer. - Past nuclear incidents lead to much higher incidents of cancer than in normal populations Chernobyl, Hiroshima Radio isotope poisoning Australia has the highest prevalence of melanoma --> high exposure to solar radiation Gives a brief explanation of the fact that radiation causes cancer. - Radiation damages cells leading to errors in replications which leads to cancer. Give a brief argument that Australia is currently experiencing the 'la nina' weather pattern - Rainfall - Previous record - inductive - Other side of the pacific is experiencing el nino --> we're in la nina Give a brief explanation of the fact that Australia is currently experiencing the 'la nina' weather pattern - Change in pressure - Change in circulation cell in the Pacific Ocean Linked v. Convergent Premises Arguments have one or more premises that support a conclusion Linked premises - Are interdependent, and support the conclusion only if taken together. Convergent premises - Are independent, each on its own provides some support for the conclusion. (If you discard a premise, and other premises still hold the conclusion may still be true)
PHIL Critical Thinking Page 4 Lecture 2 - Part 1 Sunday, 12 August 2012 9:58 AM Conditionals and Deduction Indicative sentences express propositions. The proposition expressed by an indicative sentence is what that sentence says. When someone makes a claim, they assert an indicative sentence. Sometimes there can be some confusion between conditional and causal statements. Eg. Why is Trev drunk. Because if Trev drinks too much beer, then Trev gets drunk. Probably what is meant in this case is that Trev's drinking too much causes him to be drunk. If p then q (conditional) doesn t mean p makes q happen (causal) Sufficient Condition For the standard form of the conditional "If p then q" the sufficient condition is p. The truth of p is sufficient for the truth of q. Necessary Condition For the standard form of the conditional the necessary condition is q. The truth of q is necessary for the truth of p. Equivalent forms of the conditions - p is sufficient for q - q is necessary for p - q if p - p only if q - Only if q, then p "All", "Every" and "Only" generalisations If, all, every, people, nobody - all followed by sufficient Recall objects or events are denoted by lower case letters 'a' 'b' etc. While capitol letters 'F', 'G' etc denote properties This terminology allows us to translate some conditional claims into equivalent generalisations. All Fs are Gs If I am a father than I am a parent means 'All fathers are parents' No Fs are non-g No fathers are non-parents Only Gs are Fs Only parents are fathers The only Fs are Gs The only fathers are parents The only suburbs that are more expensive than Paddington are more expensive than
PHIL Critical Thinking Page 6 Lecture 2 - Part 2 Wednesday, 8 August 2012 11:06 AM Claims, Explanations and Arguments - premise Socrates is human - premise Therefore, Socrates is mortal - conclusion Affirms the necessary condition -- Valid Socrates is mortal Therefore, Socrates is human - invalid Validity - Good form as a deductive argument - Does not say anything about the truth or falsity of its conclusion - An argument is valid when it must be the case it the premises are true the conclusion is also true - If an argument is valid then you either accept the conclusion ro reject at lease one of the premises - Valid arguments can have false premises and false conclusions Socrates is not human -- Denies the sufficient INVALID Socrates is not mortal -- Denies the necessary VALID Condition arduments - Affirm a condition to say it is true - Deny a condition to say it is false - The names we give to these four forms of conditional argument refers to what happens in the NON-CONDITIONAL premise of the argument not the concultion Four forms - Affirm the sufficient condition -- VALID - Deny the sufficient condition -- INVALID - Affirm the necessary condition -- INVALID - Deny the necessary condition -- VALID Aff suff den nec both repeat a letter in the first and second words -- VALID Only is followed b the necessary condition Only those who practice will pass the exam You practice Therefore you will pass the exam -- INVALID Only those who practice will pass the exam You will not pass the exam Therefore you do not practice -- invalid
PHIL Critical Thinking Page 8 Lecture 3 Tuesday, 6 November 2012 10:31 PM More Deduction Invalid Conditional Arguments - Affirm the necessary The non-conditional premise affirms the necessary condition of the conditional statement - Deny the sufficient The non-conditional premise denies the sufficient condition of the conditional statement Asking an argument is valid is not the same as asking if the premises and conclusion are true. Rather it is asking if it could be the case that the premises are true and the conclusion false, or if the truth of the premises guarantee the truth of the conclusion. Soundness = Validity + Only true premises Applications If we return to overseas processing the boats will stop We are returning to overseas processing Therefore, the boats will stop Modus ponens is another name for the valid form of argument that --> affirming the sufficient Modus tollens is another name for --> denying the necessary One person's modus ponens is another person's modus tollens If a foetus is a person, then abortion is impermissible Abortion is permissible Therefore, a foetus is not a person VALID -- MODUS TOLLENS If a foetus is a person, then abortion is impermissible A foetus is a person Therefore, abortion is impermissible VALID -- MODUS PONENS Disjunctive Deductive Arguments Another common form of deductive argument is a disjunctive argument. A disjunction is a claim of the form "p or q". Each part of a disjunction is called a "disjunct". In this case, one disjunct is p and he other disjunct is q. Inclusive disjunctions = 'p or q' and 'possibly both p and q' You can be an Australian citizen or the citizen of another country You are an Australian Citizen Therefore you are not the citizen of another country Exclusive Disjunctions = "p or q but not both p and q" You can be born in Australia or born in another country