PHL 137 Lecture Notes PDF

Preview

Summary

Dr Albert Atkin. Lecture Notes 1-5...

Description

PHL 137- CRITICAL THINKING Lecture One- Dr Albert Atkin (28/2/17) -

-

-

Monty Hall Problem o 3 doors, 2 goats behind 2 doors, third door has a car o pick a door, another gets open o MUST CHANGE Wason Johnson-Laird Tests o A series of tests devised in the 1970s o Presented with a simple collection of four cards and instructions about the permissible array of figures on these cards o Each card has a letter on one side & a number on the other o If it’s a vowel, its an even number on the back o Then asked to check that no impermissible array of figures has occurred by turning over the minimum no of cards o Modus ponus – logical reasoning Tooby and Cosmides Tests o Shows that humans are better at reasoning when it matters/stakes are high

Why does it matter? Lies and loose reasoning are all around you. Subtle & from many sources in advertising, medicine, politics, religion Inductive Reasoning: Using specific examples to create generalization’s Eg: apples rot, pears rot, bananas rot. Therefore, all fruit rots Deductive Reasoning: Using a general theory to test specific facts eg: all dogs bark, Rufus is a dog. Therefore, Rufus barks

Lecture 2- Dr Albert Atkin (2/3/17) (purpose to identify and analyze arguments) An argument is: 1. The attempt by one person to convince others of some claim/idea/belief 2. Convincing is done by providing evidence or reasons for belief Arguments have a particular idea/belief that they want an audience to identify and be convinced by Is this an attempt of a text/image/speech to convince some audience of a claim by citing reasons for belief? (it doesn’t matter if the argument is convincing, an attempt = an argument) What are arguments? 1. Arguments are the primary means of reasoning and persuasion a. We need to know where an argument’s persuasiveness (or lack) comes from b. Knowing and identifying good reasoning increases the ability to conduct good reasoning 2. Whoever advances an argument is the arguer. Whoever is the target is the audience Components of arguments (2 elements): 1. The conclusion- the claim the arguer is trying to convince the audience of Eg. Therefore, thus, should, must 2. The premises: the reasons cited by the arguer in favour of the conclusion Eg because for since on the grounds that the reason being

Normative terms (prescribes behavior): shows us that we are dealing with a conclusion. Eg, ought, should, must Identifying differences between arguments and explanations: • •

If the main point is relatively contrasting or surprising, it is probably an argument If there are more likely to already accept the main point, it is probably an explanation

Using the Principle of Charity- what is the fairest way to read the passage? Identifying differences between arguments and descriptions: • •

Arguments: tries to convince you that the claim is true- by using evidence Descriptions: tells you what something is/like/how something Is done They often get found together

Identifying differences between arguments and summaries • •

Arguments: tries to convince you that the claim is true- by using evidence Summary: that/what/how in condensed form (e.g. reports)

Lecture 3- Dr Albert Atkin (7/3/17): STANDARDISATION What is standardization? • • • •

A (semi) formal representation of an argyemnt that shows its claims and structure Identifies the premises and conclusion of the argyment, while disregarding all its inessential features Identifies the evidential relationship between premises and conclusion, by a conventional represention Removes and cuts away a lot of the excess o Leaves simples statements without fluff, and emotional manipulation

Putting it into standardized from: 1. -------------------- points (evidence) 2. ----------------C. Conclusion (eg capital punishment is wrong)

How to Standardise 1. 2. 3. 4.

Identify the statemtns within the passage Decide whetehr any of these are the conclusion or premises,a and if so, which is which Mark main claim or arymument with C Premises are reasons that support the claim

LINKED AND CONVERGENT PREMISES (structural relationship between premises and conclusion • •

Premise which provide independent support for the conclusion = convergent premises Premises which work together to provide joint support for the conclusion = linked premises

Therefore test: use premises and therefore to connect to the conlsuoin. Does it make sense individually, or does it need 2nd premise to make sense?

2

Eg. God must exist because the world shows signs of design and we know that a designed object cant exist without a designer Standardised: 1. 2. 3.

The world shows signs of design A designed object cannot exist without a designer God musxt exist

LINKED PREMISES (1&2)

Sometimes premises are mixed between linked and convergent

Lecture 4- Dr Albert Atkin (9/3/17): Standardization (Continued) Standardising arguments clear things up by cutting out extraneous materials, and making the statements suitably precise. It is the process of making the implicit explicit. • • • • •

Cut out the extraneous material Order the statements Identify the conclusions Identify the premises: convergent or linked Reshape the premises by paraphrasing and clarifying in the best way possible

Paraphrasing: must take care to ensure that language used has its strict and literal meaning, not vague and ambiguous. Make as literal as possible the explanation of what is meant. You might have to alter the conclusion to convey what the speaker meant, and this many not be exactly what they said

Implicit Premises and Conclusion: you may have to add an explicit premise to the standardization (often happens from an implicit premise). Paraphrase them into a sensible form, and add them to the argument. When you add the important second premise explicit, you mark it with a star at the end.* or (implicit)

3 principles of standardization to check if we are correctly making an argument clearly Fidelity: Am I being faithful to the intent of the argument? Charity: Have I presented the original argument in its best light? Temperance: Have I been balanced in the amount of detail I have included? Don’t add doo much, or too little & don’t change the intent of the original argument

SUB-ARGUMENTS • •

Premises are given to support the conclusion However, some sub arguments are given to support the premise

Eg 1.1 Sub- Premise 1.2 Sub- Premise 1. Premise “as a result of being supported as a reasons for C, me” C. Conclusion, “therefore me” • •

3

Identify if 1.1 and 1.2 are linked or convergent There can also be sub-arguments within sub-arguments o 1.1 § 1.2.1 § 1.2.2

Conclusion -

Find the main conclusion of the argument Identify the main premises supporting this conclusion For each main premise, decide whether there I any sub premise supporting it

Week 3: Lecture 5 (Constructing Your Own Arguments & Deductive Arguments) – 14/3/17 What we can do: • •

Spot the difference b/w an argument and other forms of language Standardize the arguments we find into an explicit and clarified form

Constructing your own Arguments: • What is the difference between arguments and opinions? 1. Take an opinion 2. a. Eg “Affirmative Action” b. Anyone have an opinion about it? Yes. Should we have it? c. Take the opinion i. Check terms and definitions ii. Are you using fair and even language? Are you skewing things? iii. Ask “why”? List your reasons d. Write your conclusion e. Fourth, ask “is it clear to a reasonable person ‘why’ we/I would hold these views?

DIFFERENT KINDS OF ARGUMENT Deduction: all humans are mortal, Socrates is a human, Socrates is mortal -

-

4

Has a particular type of structure, that’s what makes it a good/bad argument Deductive arguments aim to lead you from premises to conclusions in virtue of structure alone. Content/meaning is secondary Done though a concept called Validity o Validity: an argument is valid if its premises are truth preserving, given the truth of the premises the truth of the conclusion is unavoidable or automatic § A good deductive argument, is one which is valid Am I able to deny the conclusion, without having to deny the truth of at least one of the premises?

Induction: the sun came up every morning in the past, the sun will come up tomorrow Abduction/inference to the best explanation: cats are nocturnal,, cats howl at night, so the howling outside last night was the cat

Week 3: Lecture 6 (Deduction Continued) Nature of deduction: validity (makes a good argument) When we add truth, we gain soundness Rational Coherence: • • • •

We can think of our beliefs as holding together as a coherent web When you get a new belief to the web, we need to make sure it coheres with the rest of our beliefs, otherwise we find it hard to accept it People are convinced by an argument if it does not cohere with their body of beliefs What does it mean if a deductive argument is not coherent with our body of beliefs? o It is not a bad argument

Conditional Deductive Arguments: • •

• •

Conditional arguments rely for their function on conditional statements A conditional statement is a statement which takes the form of o “If…then….” sentence---- if you wear a coat, then its raining o “You are wearing a coat, if you wear a coat then its raining, so its raining” o if x, then yà each conditional statement, has 2 important parts o The crux of our argument is the conditional statement The part that follows “if” is called the ANTECEDENT The part that follows “then” is called the CONSEQUENT

1. Modus Ponens (valid point): If X then Y X

5

Therefore Y Example: “if you wear a coat then its raining. You are wearing a coat. So, its raining.” Note how the antecedent and consequent are repeated

2. Modus Tollens (denying one of the premises) If X then Y Y is not the case Therefore X is not the case.

Example: “if it is raining then it is wet. It is not wet. So, it is not raining”

3. Denying the Anticedent (incorrect): If X then Y X is not the case Therefore Y is not the case Eg:

4. Affirming the Consequent (incorrect) If X then Y Y Therefore X This form is INVALID Eg. “if you wear your coat then its raining. Its raining. So, you are wearing your coat”

Non-Conditional Deductive Arguments Reductive ad Absurdum eg. Lets assume-------. If this is true, then ------ would happen

Disjunctive Syllogism A or B Not A Therefore B (they have an either/or format) The parts that fall either side of the “or” are known as “disjuncts”

6

Categorical Arguments They function by drawing inferences about the relationships between two different categories of things or objects

Categorical Arguments- BARBARA- (3 a’s in Barbara, tells us we are dealing with 3 ALL statements) All Xs are Ys All Ys are Zs So, All Xs are Zs Example: All Socts are Britons, All Britons are Ruropean, so all Scots are European Categorical Arguments- BAROCO (1 ALL statements, 2 SOME statements) All Xs are Ys Some Zs are not Ys Some Zs are not Xs Categorical Arguments- CAMENES All Xs are Ys No Y is Z So no Z is X QUIZ •

Some things on deductive arguments

SUMMARY • •

Deductive arguments work by structure –Structure not content GET FROM SLIDES

A DEUCTIVELY VALID ARGUMENT IS ONE WHERE THE TRUTH OF THE PREMISES WOULD MAKE THE CONCLUSION CERTAIN.

7

8

Week 4: Lecture 1 (Induction) Inductive Arguments: An inductive argument aims at inductive strength, whereas a deductive argument aims at validity. -

A strong inductive argument is one where the truth of its premises would make the conclusion likely or probable Most arguments are not intended to be deductively valid.

"

Week 4: Lecture 2 – STATISTICAL GENERALISATIONS Statistical Generalisations: more common and subtle form of inductive reasoning Eg. In a sample of Fs, X% are Gs. Therefore, in the whole pop of Fs, X% are Gs. Evaluating Statistical Generalisations 1. Is the sample representative of the population?

9

(i) Is the size of the sample sufficiently large? • How large the sample just be, depends on how homogenous the population is A population is homogenous if that property is evenly distributed throughout the population A population is heterogeneous w/respect to a property if that property is unevenly distributed throughout the population. E.g. internet connection in Australia is patchy in various rural areas, hence, needs a larger sample size •

A larger sample is required for heterogeneous population, to make sure that differences in the population are reflected in the sample (ii) How was the sample selected? We need to determine whether the sample was selected in the right way Good features: randomness, stratified, self-selection (not representative, bad) Stratified: the members of the sample have the same distribution of relevant properties as the population eg ethnicity 2. Were the research methods used by the investigators adequate? (i) Was the measurement instrument appropriate? Reliable? Would give the same results under the same conditions Valid? Measures what it claims to measure (ii)

What questions were asked, and were they suitably phrased?

Questions can be very vague. (what constitutes as a lot for one, may not be a lot for another) They can be related questions, loaded questions (not suitably phrased). 3. Is the conclusion really justified? • Worth asking about newspaper reports • Often headlines do not accurately report results of research

10...