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Critical Thinking

Tim Lewis19/03/2014

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Hypothesis (OED)

• A proposition or principle put forth or stated merely as the basis for reasoning or argument, or as a premise from which to draw a conclusion.

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Hypothesis

• An hypothesis is a specific statement of prediction. It describes in concrete (rather than theoretical) terms what you expect will happen in your study. Not all studies have hypotheses. Sometimes a study is designed to be exploratory. There is no formal hypothesis, and perhaps the purpose of the study is to explore some area more thoroughly in order to develop some specific hypothesis or prediction that can be tested in future research. A single study may have one or many hypotheses.

• http://www.socialresearchmethods.net/kb/hypothes.php

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Thesis (OED)

• A proposition laid down or stated, esp. as a theme to be discussed and proved, or to be maintained against attack.

• A dissertation to maintain and prove a thesis; especially one written or delivered by a candidate for a university degree 1653.

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The Nature of Argument

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Argument

• an argument is an attempt to persuade someone of something, by giving reasons for accepting a particular conclusion as evident. The general structure of an argument … is that of premises (typically in the form of propositions, statements or sentences) in support of a claim: the conclusion

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Syllogisms

(Major) Premise : All men are mortal(Minor) Premise : Socrates is a manConclusion: Therefore Socrates is mortal

(Major) Premise : All kittens are playful (Minor) Premise: Some pets are kittens (Conclusion): Some pets are playful.

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False Syllogisms

• All dogs can fly.• Fido is a dog.• Fido can fly. • Slavery is work. • Slavery is evil.• Therefore all work is evil.

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Syllogism -definition

• A syllogism is a kind of logical argument in which one proposition is inferred from two or more others (the premises) of a specific form. A syllogism has three parts: major premise, minor premise, and conclusion. The major premise of a syllogism makes a general statement that the writer believes to be true. The minor premise presents a specific example of the belief that is stated in the major premise. If the reasoning is sound, the conclusion should follow from the two premises.

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Deductive Argument

• Deductive reasoning is the process of reasoning from one or more general statements (premises) to reach a logically certain conclusion.

• Premises are linked with conclusions by a process of inference. If all premises are true, the terms are clear, and the rules of deductive logic are followed, then the conclusion reached is necessarily true.

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Inductive Argument

• Inductive reasoning is reasoning in which the premises seek to supply strong evidence for (not absolute proof of) the truth of the conclusion. While the conclusion of a deductive argument is supposed to be certain, the truth of an inductive argument is supposed to be probable, based upon the evidence given.

• Inductive reasoning forms the basis of most scientific theories e.g.; Darwinism, Big Bang Theory and Einstein’s Theory of Relativity.

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Arguments: logic and rhetoric

• The standards and criteria used in evaluating arguments and their forms of reasoning are studied in logic. Ways of formulating arguments effectively are studied in rhetoric (also known as argumentation theory).

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Deduction and Induction

Handout

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Fallacies (1)

• Guilt by Association: “Hitler was a vegetarian, therefore, I don’t trust vegetarians.”

• Ad Hominem: “Don’t listen to Eddie’s arguments on education, he’s an idiot.”

• Appeal to Authority: “Well, Isaac Newton believed in Alchemy, do you think you know more than Isaac Newton?”

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Fallacies (2)

• Argument from Ignorance: “No one has been able to disprove the existence of UFOs, therefore they exist.”

• Non sequitur: “I read about a pitbull attack. My neighbour owns a pitbull. My life is in danger.”

• Slippery slope: “If voluntary euthanasia is legalised it will be impossible to avoid the legalisation, or, at least, toleration, of non-voluntary euthanasia.”

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Activities

• 1. The Sun says: Arrogant LeftReconstitute the argument of this Sun editorial in the form of a syllogism (a deductive argument).

• 2. Sex Vote Labour Chiefs/Scientists’ Hidden Links to the GM Food Giants

What kind of arguments are being used in these two handouts?

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Sun Leader as syllogism

P1 Senior members of the Labour Party tolerated paedophiles in the 1970s.

P2 Their refusal to apologize for this has been supported by Ed Miliband as party leader.

C He and they are guilty of arrogant defiance.

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Using Evidence

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Evidence

• Evidence, broadly construed, is anything presented in support of an assertion. This support may be strong or weak. The strongest type of evidence is that which provides direct proof of the truth of an assertion. At the other extreme is evidence that is merely consistent with an assertion but does not rule out other, contradictory assertions, as in circumstantial evidence.

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Scientific Evidence

• Scientific evidence consists of observations and experimental results that serve to support, refute, or modify a scientific hypothesis or theory, when collected and interpreted in accordance with the scientific method.

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Handouts

• Home Secretary speech on `An immigration system that works in the national interest’

• Article by Jonathan Portes (National Institute of Economic and Social Research) `Theresa May’s immigration speech: facts or fiction’

• Article by Andrew Grice (Political Editor, The Independent) `May’s stance on immigration and jobs “not proven”’

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Using Evidence 1

1. Read pp. 1-4 of Theresa May’s speech: `An Immigration system that works in the national interest’.

2. List all the sources of evidence identified by Theresa May.

3. List the three areas in which May claims immigration has a negative impact.

4. Identify any conclusions for which May says that there is `evidence’.

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Sources of evidence identified by Theresa May:

• yesterday’s census statistics (p.1)• official statistics released two weeks ago (p.1)• Home Office visa statistics (p.1)• which are more up to date than• net migration figures (p.1)• • the Migration Advisory Committee report (p.4)• which is based on • several academic studies (p. 4)

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The three areas in which May claims immigration has a negative impact

• social cohesion• infrastructure (especially housing)

and public services• employment (jobs and wages)

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Conclusions for which May says that there is `evidence’

• ` There is evidence that without the demand caused by mass immigration, house prices could be ten per cent lower over a twenty year period’ (p.3)

• `There is evidence … that immigration puts downward pressure on wages’ (p.4)

• `That is evidence of an immigration system that does not work in the national interest’ (p.4)

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Using Evidence 2

• Read Jonathan Portes’ Article `Theresa May’s immigration speech: facts or fiction?’

• List up to five main criticisms Jonathan Portes makes of Theresa May’s use of evidence

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Five criticisms of Theresa May’s use of evidence

1. May’s use of statistical evidence is HIGHLY SELECTIVE (p.2). She OMITS inconvenient points and restrictions (p.4).

2. May EXAGGERATES, or goes `well beyond what the MAC said or what the research actually found’. (p.2)

3. May argues by IMPLICATION and (p.3)4. Some of May’s arguments ARE NOT BORNE OUT by,

or are CONTRARY to the evidence. (p.3)5. May’s IDENTIFICATION OF the SOURCES for some of

her claims is UNCLEAR. (p.4)

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How to deal with evidence

1. Present ALL the evidence you have, or at least a REPRESENTATIVE SAMPLE of it.

2. DO NOT EXAGGERATE the claims you make, beyond what the evidence will bear.

3. Make your arguments OVERT and EXPLICIT.4. Check that your ARGUMENTS are IN LINE

WITH the EVIDENCE5. Always IDENTIFY YOUR SOURCES CLEARLY and

as SPECIFICALLY as possible.

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Critical Reading

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Handout and Activity

1. Read Wallace and Wray, Chapter 3 `Getting Started on Critical Reading’ and

2. Answer the questions on the worksheet

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References

• http://www.socialresearchmethods.net/kb/• http

://plato.stanford.edu/entries/logic-informal/• Mike Wallace and Alison Wray, Critical Reading

and Writing for Postgraduates, 2nd edition (London: Sage, 2011)

• Christopher W. Tindale, Rhetorical Argumentation: Principles of Theory and Practice (Sage: Thousand Oaks Ca, 2004)