Critical Thinking

Ronald S. Lau, Ph.D.

HKUST – ISOM

Learning to make better decisions through critical thinking

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To live is to act. To act is to decide. Everyday work and life are an endless sequence of decisions. Some of the decisions are small and inconsequential, and some are large and life-determining. When your patterns of decision-making are rational, you live a rational life. When your patterns are irrational, you live an irrational life. Rational decisions maximize the quality of your life and your chances of happiness, successful living, and fulfillment. Critical thinking improves your decision-making abilities by raising your patterns of decision-making to the level of conscious and deliberate choice.

http://www.criticalthinking.org/conference/Business_Seminar.cfm

Role of critical thinking in decision making and problem solving

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Critical Thinking

Analytical Thinking

Statistical Thinking

Decision Making

Problem Solving

Reasonable reflective thinking focused on deciding what to believe or do

Active systematic process of understanding and evaluating arguments

Multiple dimensions of critical thinking

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Verbal reasoning

Argument analysis

Thinking as

hypothesis testing

Likelihood and

uncertainty

Decision making

and problem solving

Introduction to critical thinking

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http://www.youtube.com/watch?v=oefmPtsV_w4

What is critical thinking?

Critical = Evaluative ( Skeptical)

6 Source: http://www.asa3.org/ASA/education/think/critical.htm

How to be evaluative (skeptical)?

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Analyzing Conceptualizing Defining Examining Inferring Listening Questioning Reasoning Synthesizing

Evaluating information

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Evaluating our thought

in a disciplined way

Help us refine our thought process

• Think and process information more comprehensively • More able to identify and reject false ideas/ideologies

Source: http://www.youtube.com/watch?v=6OLPL5p0fMg

Becoming a critical thinker

We can be a critical thinker if we: Recognize the flaw in our thinking (incl. decision traps)

Develop a habit of being critical (evaluative or skeptical)

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…and we could be another Sherlock Holmes!!!

Incorporating logic in the thinking process

Logic is the activity of drawing inferences (conclusions) from a body of information

Symbolic or formal logic Emphasize on the precise symbolic representation of logical

concepts, the study of the abstract relationships between these concepts, and the systematization of these relationships

Example: All members of al-Qaeda are our enemies and bin Laden is a member of al-Qaeda bin Laden is our enemy

Informal logic (critical thinking) Emphasize on the application of logical concepts to the analysis

of everyday reasoning and problem solving

Use of reason in the pursuit of truth

Example: Why all members of al-Qaeda are our enemies?

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We always think we are logical…

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Getting started with logical vocabulary

Statement or proposition A sentence which has a truth-value, either true or false

Example: The moon is 150 miles above the earth (?)

Argument A collection of statements

Supporting statements are referred to as premises and the one supposedly being supported is called the conclusion

Argument based on inductive vs. deductive reasoning

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Reasoning: Inductive vs. Deductive

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Specific

Specific General

General Induction

Deduction

Example: I've noticed previously that every time I kick a ball up, it comes back down. So next time when I kick it up, it will come back down.

Example: According to the Newton's Law, everything that goes up must come down. So, if you kick the ball up, it must come down.

http://www.youtube.com/watch?v=X8xxtygm_xM

Making a valid deductive argument

Inductive argument The conclusion probably follows from its premises

Strong vs. weak

Deductive argument The conclusion is claimed to necessarily follow from its premises

Valid vs. invalid

Validity

About the logical connection between premises and a conclusion

Valid argument when a conclusion follows from premises

If all premises are true/acceptable, the conclusion must also be true/acceptable

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Assessing the validity with a Truth Table

Validity Validity concerns the relationship between the premises and the

conclusion, and not the actual truth values of the component statements (i.e., soundness)

The validity of logical implications “if p then q” can be assessed by a Truth Table:

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p q p q

T T T

T F F

F T T

F F T

A valid argument does not imply true premises and a true conclusion

Examples

“All pigs can fly. Anything that can fly can swim. Therefore, all pigs can swim.”

Premises and conclusion of a valid argument can possibly be false

“A loves B. B loves C. Therefore, A loves C.”

Argument can possibly be invalid even if the conclusion and premises are all true

“All pigs are purple in color. Anything that is purple is an animal. Therefore, all pigs are animals.”

A valid argument can possibly have a true conclusion but false premises

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Is it possible that 1 = 2?

a = b Start with this

ab = b2 Multiply by b

ab – a2 = b2 – a2 Subtract a2

a(b – a) = (b – a) (b + a) Factor

a = b + a Divide by (b – a)

a = a + a Since a = b, substitute

a = 2a Simplify

1 = 2 Divide by a

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Making a sound deductive argument

Soundness

Must be valid

Every premises has to be either true or acceptable

Example

Valid and sound argument

“Cows are mammals. Mammals are animals. Therefore, cows are animals.”

Valid but unsound argument

“Cows are insects. Insects are mammals. Therefore, cows are mammals.”

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Classification of arguments

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Fallacies

Potential problems with premises Factual errors, intentional or unintentional

Unwarranted assumption (people tend to choose assumptions that best fit the conclusion they prefer)

Hidden or unstated major premises

Logical fallacies Even when all premises of an argument are reliably true, it may

still be invalid if the logic employed is not legitimate

Deceptive arguments in which the conclusion is not well supported by the premises

Examples

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Valid vs. fallacious argument

20 For more example, http://www.don-lindsay-archive.org/skeptic/arguments.html

Valid argument Fallacious argument

False premises lead to doubtful conclusions

Fallacy An argument that tends to persuade us, even though it is a bad

argument

Can be a valid but not sound argument, “If A then B”

Fallacies of deception Distraction

Counterfeit

Fallacies that use motive Appeal to force (or fear)

Appeal to pity

Prejudicial use of language

Appeal to authority

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http://www.msnbc.msn.com/id/3032619/

Example: Clinical research humor…

The Japanese eat very little fat and suffer fewer heart attacks than the British or the Americans.

On the other hand, the French eat a lot of fat and also suffer fewer heart attacks than the British or the Americans.

The Japanese drink very little red wine and suffer fewer heart attacks than the British or the Americans.

The Italians drink excessive amounts of red wine and also suffer fewer heart attacks than the British or the Americans.

Conclusion?

Eat and drink whatever you like. It's speaking English that kills you.

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