PHI2100 01 Midterm Review Part One Arguments Fallacies V 1 Argument set of premises that give us reason to believe that a conclusion is true Explanations arguments attempt to show that something is true v Explanations attempt to show how something is true Threats bribes arguments aim to give you reason to believe something is true v Threats and bribes give you a reason in the sense of a motive to believe something 2 How to identify arguments look for conclusion and PREMISES 3 Requirements for a good argument in general 1 A good argument must have all true or at least plausible premises 2 Premises must support conclusion that gives us some reason to believe that the conclusion A list of premises separated from the conclusion by a horizontal line the support of the premises is measured through validity and soundness Forms of valid arguments is true standard 4 Argument in form Ex 1 All men are mortal 2 Socrates is a man 3 Therefore Socrates is mortal 5 Deductive Argument Modus Ponens 1 If P then Q 2 P 3 Therefore Q Modus Tollens 1 If P then Q 2 Not Q 3 Therefore not P Hypothetical Syllogism 1 If P then Q 2 If Q then R 3 Therefore if P then R Disjunctive Syllogism 1 P or Q 2 Not Q 3 Therefore P Or 1 P or Q 2 Not P 3 Therefore Q 6 Validity and soundness truth preserving conclusion can be false 1 A valid deductive argument if the premises are true then the conclusion has to be true 2 An invalid deductive argument is an argument that can have premises that are true but the 3 Deductively sound means if a deductive argument is valid AND the premises are true 4 Unsound deductive argument is an argument that is either invalid or the premises are not true or both 7 Antecedent and consequent of conditional if then statements If x antecedent then y consequent 8 Inclusive v Exclusive Disjunctive statements Inclusive the sense of or here does not rule out both parts disjunct of the argument the statement can be true if they are both true in logic this is used ex If you want to go snorkeling go to the Florida Keys or Hawaii Exclusive the sense of or here does rule out both parts disjuncts of the argument ex Disjunctions are a compound composition using the connective or Arguments where the conclusion follows from the premises not with necessity but with assessed through strength and cogency Either you drive or I drive 9 Inductive arguments probability Ex 1 Josh is left handed 2 90 of left handed people experience difficulty using can openers made for right handed people 3 Therefore Josh has trouble using can openers for right handed people 10 Inductive strength and cogency Inductive strength is measured to the extent that the conclusion is probable given the premises conclusion more probable This is a matter of degree unlike validity An inductive argument has strength in so far as the premises if true make the Inductive cogency is strong strength and premises being true 11 Abductive Argument Arguments to the best explanation The conclusion stands as an explanation for the facts given in the premises The conclusion stands as an explanation for the facts given in the premises Ex 1 I have a headache 2 I m having trouble concentrating 3 So I must have a brain tumor 12 4 features of a good Abductive argument 1 Simplicity go with least complicated explanation 2 Coherence go with explanation that s consistent with what experts about the subject or other related subjects already believe to be true 3 Testability predictive power go with the theory that yields the most predictions that can be 4 Comprehensiveness go with the explanation that leaves the least things unexplained Fallacy is an instance of poor reasoning faulty inference Formal fallacy faulty reasoning where the fault is in the structure or form if the argument all confirmed or disconfirmed 13 Formal informal fallacies invalid arguments are formal fallacies A Affirming the consequent 1 If p then q 2 q 3 Therefore p B Denying the antecedent 1 If p then q 2 Not p 3 Therefore not q C Affirming the disjunct 1 Either P or Q 2 P 3 Therefore not Q D Undistributed middle 1 All A is P 2 All B is P 3 Therefore all B is A Informal fallacies when the fault of the reasoning lies in the content of the argument rather than the form actually more options A Equivocation when the same word is used with 2 different meanings B False dilemma when a limited number of options are given usually 2 when there are C Begging the question to assume in your premises what you are trying to prove D Straw man fallacy when interpreting another s theory or argument not practicing the principles of charity and fidelity see point 14 15 of study guide for Part One E Ad Hominem 3 types argument or assertion itself 1 abusive attacks the person making an assertion or argument rather than the assertion and the circumstances of that person 2 circumstantial occurs when one points our the relationship of the person making an 3 Tu quoque an attack that notes that one does not practice what he preaches F Illicit appeal to authority appealing to authority inappropriately when The person is not qualified to have an expert opinion on the subject Experts in the field disagree on the issue The authority was not being serious or was making a joke G Hasty generalization sample size is too small to support the conclusion Maximize the sound of argument you are discussing by giving someone the best possible strongest argument must assume premises are true and valid Attacking the strong man 14 Principle of charity 15 Principle of fidelity When attacking or discussing the argument you want to attack the argument as accurate as possible you want to have the most accurate argument Actually capturing what the person is saying and understanding it Part Two Misleading Numbers Graphs 1 All claims of the form the average of X is Y is ambiguous because average can mean median mode or mean 2 Mean median mode Mean Arithmetic averages of a range of values add values divide by of values Median midpoint value in a range of values ordered from least to greatest Mode value that occurs most frequently in a range of values 3 Salaries of five elementary teachers 25 000 25 000 30 000 50 000 70 000 a median salary 30 000 b mean salary 40 000 mode 25 000 c average according to union rep can be 25 000 d average according to school board can be 40 000 4 Ways of lying with numbers told what yardstick 1 No comparison comparison an item that s being compared to something else but you re not Ex Twin clean cleans 50 better