Philosophy in Practice

Lecture 3: Introduction to Critical Reasoning

Outline of the lecture

• Recap: last lecture• Identifying premises and conclusions• Implicit/explicit premises and conclusions• Fallacies to look out for•Module assessments

Antecedent and consequent

A conditional statement is one that is structured like this: “if…then…”. So a conditional statement is composed of two parts:

• The first part is called the antecedent (and follows ‘if’)• The second part is called the consequent

(and follows ‘then’)

If antecedent, then consequent

Necessary and sufficient• The antecedent is supposed to be sufficient

(enough) for the consequent.• The consequent is supposed to be necessary (required) for the antecedent.

If you were born in London, then you were born in England.• Being born in London is sufficient but not necessary for being born in England.• Being born in England is necessary but not sufficient for being born in London.

Affirming the antecedentP1: If the mind and body are distinct then we may survive our bodily deaths.

P2: The mind and body are distinct.

_________________________

C: We may survive our bodily deaths.

If P, then QPTherefore Q

Valid argument, also known as ‘modus ponens’.

Denying the consequentP1: If backwards time travel were possible, then people would have come back from the future to visit us.

P2: People haven’t come back from the future to visit us.

_________________________

C: Backwards time travel is not possible.

If P, then QNot-QTherefore, not-P

Valid argument, also known as ‘modus tollens’

Disjunctive syllogismP1: Either the giant duck is the biggest bird or the giant sparrow is the biggest bird.

P2: The giant sparrow is not the biggest bird.

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C: The giant duck is the biggest bird.

Either P or Q Not-QTherefore, P

Valid argument

Affirming the consequent

P1: If the suspect is lying, he will start sweatingP2: The suspect is sweating._________________________C: The suspect is lying.

If P, then QQTherefore, P

Invalid argument

Denying the antecedent

P1. If it's raining, then the streets are wet. P2. It isn't raining. _________________________C. The streets aren't wet.

If P then QNot-PTherefore, not-Q

Invalid argument

Conditionals vs. arguments

Note the key difference between conditionals and arguments.

• Conditionals can be true or false• Arguments can be valid or invalid 

Identifying argumentsIn our increasingly atheist society, most people now implicitly endorse materialism about the most profound of metaphysical questions. One primary example of this is the question of the relationship between the mind and the brain. Many just take it for granted that all mental phenomena can be explained in terms of physical processes in the brain. People really need to snap out of this science delusion.

Q: is this an argument? If so, what is the conclusion and what are the premises?

Identifying arguments (1) In our increasingly atheist society, most people

now implicitly endorse materialism about the most profound of metaphysical questions. (2) One primary example of this is the question of the relationship between the mind and the brain. (3) Many just take it for granted that all mental phenomena can be explained in terms of physical processes in the brain. (4) People really need to snap out of this science delusion.

No argument. (1)-(3) are scene-setting.

(4) is an unsupported assertion.

Identifying arguments

There is a trend today that supports regulating British industry in the name of the environment. For example, ‘green’ organisations advocate the placing of limitations on the amount of carbon our industries can expel into the atmosphere. It is my view that we must not give in to this demand. The principal reason for this is that curbing carbon emissions simply will not solve the problem that it is supposed to address: the problem of global warming. We shouldn’t adopt policies that don’t solve the problems they are supposed to address.

Q: is this an argument? If so, what is the conclusion and what are the premises?

“(1) There is a trend today that supports regulating British industry in the name of the environment. (2) For example, ‘green’ organisations advocate the placing of limitations on the amount of carbon our industries can expel into the atmosphere. (3) It is my view that we must not give in to this demand. (4) The principal reason for this is that curbing carbon emissions simply will not solve the problem that it is supposed to address: the problem of global warming. (5) We shouldn’t adopt policies that don’t solve the problems they are supposed to address.”

Conclusion: Sentence (3): We should not limit carbon emissions. Premises: Sentences (4) and (5) • Limiting carbon emissions will not solve the problem that

it is supposed to address (global warming).• We should not adopt policies that don’t solve the

problems they are supposed to address Extraneous Material: Sentences (1) & (2): scene-setting & rhetoric

Reconstructing arguments

P1: Limiting carbon emissions will not solve the problem that it is supposed to address (global warming).P2: We should not adopt policies that don’t solve the problems they are supposed to address.______________________________C: We should not limit carbon emissions.

Implicit/explicit

You should avoid Danny. He has some very dubious ideas. For proof of this, look no further than the fact that he’s a member of the BNP!

Q: is this an argument? If so, what is the conclusion and what are the

premises?

Implicit/explicitYou should avoid Danny. He has some very dubious ideas. For proof of this, look no further than the fact that he’s a member of the BNP!

Conclusion: You should avoid Danny. (explicit)Explicit Premises: • Danny is a member of the BNP. • Danny has some very dubious ideas.Implicit Premises: • (1) If you are a member of the BNP then you have

some very dubious ideas. (2) If someone has very dubious ideas then you should avoid them.

Reconstructing argumentsYou should avoid Danny. He has some very dubious ideas. For proof of this, look no further than the fact that he’s a member of the BNP!

P1: If you are a member of the BNP then you have very dubious ideas.P2: Danny is a member of the BNP.___________________________________C1: Danny has very dubious ideas.

Reconstructing argumentsYou should avoid Danny. He has some very dubious ideas. For proof of this, look no further than the fact that he’s a member of the BNP!

P1: If you are a member of the BNP then you have very dubious ideas.P2: Danny is a member of the BNP.____________________C1: Danny has very dubious ideas.P3: If someone has very dubious ideas then you should avoid them.____________________C2: You should avoid Danny.

Implicit/explicitIn our disenchanted society it has become fashionable to say that morality is all just a matter of opinion. But if morality was subjective then people wouldn’t think that it is possible to be mistaken about moral matters. With this in mind consider the following: we think that previous generations were in error when they believed that slavery wasn’t wrong. Also, we think that psychopaths who say there is nothing wrong with killing innocent people are saying something which is obviously false. I really think people should reflect more about these things.

Q: is this an argument? If so, what is the conclusion and what are the premises?

Implicit/explicit(1) In our disenchanted society it has become fashionable to say that morality is all just a matter of opinion. (2) But if morality was subjective then people wouldn’t think that it is possible to be mistaken about moral matters. (3) With this in mind consider the following: we think that previous generations were in error when they believed that slavery wasn’t wrong. (4) Also, we think that psychopaths who say there is nothing wrong with killing innocent people are saying something which is obviously false. (5) I really think people should reflect more about these things.Conclusion: Morality is not subjective (implicit).Premises:Explicit (sentence (2)): If morality was subjective then people would not think that it is possible to be mistaken about moral matters.Implicit ((3) and (4)): People do think that it is possible to be mistaken about moral matters.Extraneous material: (1): scene setting; (5): irrelevant observation.

Reconstructing arguments

P1: If morality was subjective then people would not think that it is possible to be mistaken about moral matters.P2: People do think that it is possible to be mistaken about moral matters.__________________________________C: Morality is not subjective.

Implicit/explicitThey recycle obsessively, insist on real nappies and compost every scrap of organic vegetable peeling and used Fair Trade teabags – and they’re not slow to tell you about it. But when it comes to sacrificing their jaunts to Tuscany and weekend breaks in Prague, it seems that even the most pious of green crusaders waver in their zeal for saving the planet. Coldplay frontman Chris Martin - who uses his lyrics to urge environmental responsibility - flies home between gigs, while George Clooney – who drives a low-emissions Tango car – also uses private jets. It goes without saying what the public’s attitude ought to be towards the advice of both of these eco-hypocrites.

Q: is this an argument? If so, what is the conclusion and what are the premises?

(1) They recycle obsessively, insist on real nappies and compost every scrap of organic vegetable peeling and used Fair Trade teabags – and they’re not slow to tell you about it. (2) But when it comes to sacrificing their jaunts to Tuscany and weekend breaks in Prague, it seems that even the most pious of green crusaders waver in their zeal for saving the planet. (3) Coldplay frontman Chris Martin - who uses his lyrics to urge environmental responsibility - flies home between gigs, while George Clooney – who drives a low-emissions Tango car – also uses private jets. (4) It goes without saying what the public’s attitude ought to be towards the advice of both of these hypocrites.Conclusion: Implicit in sentence (4): We should ignore the advice of Chris Martin and George Clooney about living in an environmentally friendly way.Premises: • Implicit in sentences (2) (3): The behaviour of Chris Martin and

George Clooney is inconsistent with their advice about living in an environmentally friendly way.

• Implicit: Whenever someone’s behaviour is inconsistent with their advice, we should ignore the advice

Extraneous Material: Sentence (1) – scene-setting, rhetoric. Sentence (2) – scene-setting, more rhetoric.

Reconstructing arguments

P1: The behaviour of Chris Martin and George Clooney is inconsistent with their advice about living in an environmentally friendly way.P2: Whenever someone’s behaviour is inconsistent with their advice, we should ignore the advice. ______________________________C: We should ignore the advice of Chris Martin and George Clooney about living in an environmentally friendly way.

Keep in mind…

• Premises are either true or false. Therefore, questions and commands cannot figure as premises or conclusions.

When reconstructing arguments:• The sentences we use need not be the same as the

sentences used by the arguer• We’re trying to express what the arguer is saying

more clearly (but without, of course, changing what they’re saying)• In addition, our reconstruction may contain premises

that are not expressed by any of the sentences actually used by the arguer

Keep in mind…

This is not an exact science:

“It cannot be mechanical or foolproof. It calls for judgment, a critical but sympathetic eye or ear and even a degree of intuition, of understanding of people – of the ways people tend to think in given sets of circumstances, and some of the typical ways in which people fail to express themselves clearly.”(Bowell and Kemp, 2nd Edition: Ch.2 p. 45; 3rd

Edition: Ch.3, p. 57)

Keep in mind…

The principle of charity

If we are interested in whether the conclusion is true or not, or whether we have in fact been given good reasons for thinking it to be true, then we should aim to reconstruct the argument in its strongest form.

Deriving ‘ought’ from ‘is’

This is the fallacy of deriving a prescriptive conclusion (i.e., a conclusion about what ought to be done, or what should be done, or what is good, bad, wrong, right) from non-prescriptive premises.

P1: Capitalism inevitably leads to financial crises.______________________________C: We should overthrow capitalism.

In order to be valid, we need a prescriptive premise linking X’s leading to financial crises and it being the case that X should be overthrown.

Fallacy of majority beliefMajority Belief: This is the fallacy of concluding on the basis of the fact that most people believe some proposition, p, that p is true.

Although there is a tiny minority of people who disagree with our health care reforms, the overwhelming majority of British citizens know that they will make the NHS better. In light of this overwhelming consensus it is clear that this Government’s health policy is going to greatly improve our National Health Service.

P1: The majority of people believe that the that the reforms will make the NHS better.

P2: Any belief held by the majority is true. (false)________________________________ C: The health care reforms will make the NHS better.

The report (submit week 10)

• Write the report as though it’s going to be presented to the public (i.e. it’s not a formal essay). The report has to be accessible to someone who hasn’t studied any philosophy. Think about the best way to communicate the arguments.

• You may want to approach this by taking both sides of the argument, or breaking down the dominant argument.

• Feel free to use bullet points if that makes things better.

• Choose a topic that interests you.

Some suggestions:

• Abortion

• Euthanasia

• Animal rights

• Affirmative action

• Capital punishment

• Racial profiling

• Same-sex marriage

• Pornography

• Decriminalisation of drugs

• Immigration

• Humanitarian intervention

• World hunger

Presentation

• Lecture next week on presentations• Workshops in week 7 (sign up on Tabula)• Optional workshop in week 8 (max. 20

places)• You will submit your presentation (hand-

out, PowerPoint, Prezi etc. as part of your assessment)• Presentations in front of seminar groups

(weeks 9 and 10)• Not a charisma contest

Précis

• Submit word précis in week 5• 450-500 words (no more or less)• The précis is a concise summary of your report

(an overview of the argument)• What are the questions you’ll look at? • What are the problems that define the issue? • What is your angle going to be? • It’s difficult to summarise the argument before

you’ve done extensive research, so you will have to do some of the research over the next fortnight.

BibliographyBibliographyArgyle, Fiona. 2002. Footwear and Cultural Subversion (Cambridge, MA: Hardware University Press).Bunion, Dan. 1978. ‘Polyester Blends and Thin Concepts’, Podological Review, (89), pp.115-39.Calcetin, Alicia (ed.). 1981. Socks on Feet, Socks on Trial, 3 vols (Laramie, WY: University of Heel Press).Hose, Ivan, and Louise Chaussette. 2006. ‘Let the Socks Fall Where They May’, in Culture Online http://www.cultonline.co.uk [accessed 29 April 2007].Nehigh, Anders. 2004a. Socks and Necessity (Oxford: Harendon Press).______ 2004b. ‘Socks and the Separation of Shoes and Feet: A Critical Survey’, in Brownwell Companion to Philosophy and the Lower Limbs, ed. Carol Leggett (London: Brownwell), pp.3-37.Sandal, Greta. 1957. Wool, Elastic, and the Wearable, trans. Kurt Tonhale (New York: Harper & Towe).

BibliographyPlato – The Symposium – translated by Christopher Gill for Penguin Classics, 1999• Frisbee C.C. Sheffield – 2006. The Role of the

Earlier Speeches in the Symposium: Plato's Endoxic Method? - Harvard University Press

Ludwig Edelstein - The Rôle of Eryximachus in Plato's Symposium, Transactions and Proceedings of the American Philological Association, Vol. 76 – American Philological Association, 1945 - http://www.jstor.org/stable/283327