Unit 1 Logic and Critical Thinking - memelyceum.com · Unit 1 Logic and Critical Thinking Concept...

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Instructor – Jeremy Beahan

Unit 1 Logic and Critical Thinking

Concept

Analysis

Breaking down an idea, concept, theory, etc. into its most basic parts in order to get a better understanding of its structure.

• This is necessary to evaluate the merits of the claim properly (is it a fact, probably true, possibly true, impossible?).

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Concept

Analysis

We begin with identifying the basic components of any argument:

•argument indicators• premises• conclusions• assumptions

1. All humans are mortal2. Socrates is a human

Therefore, Socrates is mortal

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Anatomy of an Argument

Proposition: A statement or sentence that declares something to be true. (It is snowing outside, killing people is wrong, there is an invisible dragon in my garage).

Premise: Any proposition used as evidence to support another proposition.

1. All humans are mortal

2. Socrates is a humanTherefore, Socrates is mortal

Anatomy of an Argument

Inference: An inference is the move one makes from reasons to a conclusion.

• When we conclude that something is true in the light of some set of reasons we have made an inference. Inferences can either be justified (valid) or unjustified (invalid) depending on what support the reasons give to the conclusion.

1. All humans are mortal2. Socrates is a humanTherefore, Socrates is mortal

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1. All humans are mortal2. Socrates is a human

*inference*

Therefore, Socrates is mortal

Premise

Conclusion

Concept

Analysis: Argument indicators

Argument indicators: language that commonly indicates the presence of reasons or conclusions.

1. conclusion indicators: words that point to a conclusion that has been reached.

Examples: “Therefore…”•So •Hence•Consequently•Which Proves…•Which Establishes…•Justifies the view that…•In conclusion•From which we can infer…•It follow that…•Demonstrates that…

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Concept

Analysis: Argument indicators

Argument indicators: language that commonly indicates the presence of reasons or conclusions.

2. reason indicators: words that point to a reason that has been offered in support of a conclusion.

Examples: “because…”•Since•For •Follows form the fact that•The reasons are•First, second, etc. •If…then

Concept

Analysis: Checking for assumptions

Check for assumptions. In your analysis could you find any assumptions…

a) That seem likely in the contextb) Which must be added to the argument to make sense of what is saidc) Which seem necessary to make the reasoning as strong as possible.

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Concept

Analysis: Argument Key

<Reasons/Premise>

[Conclusions]

Argument indicators

Assumptions:

Will be written out

<I want you to be strong, confidentIndependent thinkers> so [I’m teachingYou how to analyze arguments]

Assumption: •analyzing arguments will makeSomeone a strong, etc. thinker (stated)• That you are not already actively doing these things (unstated)

Concept

Analysis: diagramming arguments

Arguments can get very long and complicated. When this happens it is useful to construct a diagram of the argument to illustrate how the premises support the conclusion.

Argument Patterns:

1. Vertical Patternor chain.

The premise directly supports a conclusionwhich can become the premise for anotherconclusion further down the chain. Each linkin the chain depends on the others.

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Concept



Argument Patterns:

2. Horizontal Pattern

In a horizontal pattern each premisesupports the conclusion independently

Concept



Argument Patterns:

3. Conjoint Premises

When two or more premises support a Conclusion conjointly. On it’s own, neither Premise would lend any support to the conclusion.But together they can lend support.

*this relationship can be reversed where one Or more Premises support multiple conclusions

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Concept

Evaluation: Deductive vs Inductive Arguments

All arguments fall into one of two categories: deductive arguments and inductive arguments.

Deductive arguments: where the conclusion follows with certainty.

In a good deductive argument it is impossible for the conclusion to be false supposing the premises are true (whether they are actually true in reality is irrelevant to validity).

Concept

Evaluation: Deductive vs Inductive Arguments

All arguments fall into one of two categories: deductive arguments and inductive arguments.

Inductive arguments: Arguments where the conclusion probably follows from the premises. In a good inductive argument it is improbable that the conclusion is false, if the premises are true.

Inductive arguments are judged by the probability of their conclusions being true (supposing their premises are true).

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What is the difference between a deductive argument and an inductive argument?

Inductive or Deductive?

Classical mathematics began in either ancient Greece or ancient Egypt. New evidence conclusively rules out an Egyptian origin. So it must have originated in ancient Greece.

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“Animals that live on plant foods must eat large quantities of vegetation, and this consumes much of their ties. Meat eaters, by contrast, have no need to eat so much or so often. Consequently, meat-eating hominines [early humans] may have had more leisure time available to explore and manipulate their environment.”

- Haviland’s Cultural Anthropology


“The incident had shown me that a dog was kept in the stables, and yet, though someone had been in and had fetched out a horse, he had not barked enough to arouse the two lads in the loft. Obviously the midnight visitor was someone whom the dog knew well.”

-Memoirs of Sherlock Holmes

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“Each element, such as hydrogen and iron, has a set of gaps—wavelengths that it absorbs rather than radiates. So if those wavelengths are missing from the spectrum, you know that that element is present in the star you are observing.”

-Gore’s Eyes of Science

Concept

Evaluation: Deductive Arguments

Here are the terms we will be using for evaluation of deductive arguments:

Valid – the premises support the conclusion

Invalid—the premises do not support the conclusion

Sound—valid, with true premises

Unsound—either invalid or valid, with false premises

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Valid vs. Sound Arguments

1. All S are P.

2. All M are S

Therefore: All M are P.

Standard Form Categorical Syllogism

1. All persons who are men (S) are persons who are mortal (p)2. All persons identical to Socrates (m) are persons who are men (S)Therfore, All persons identical to Socrates are persons who are mortal

(When arguments are translated into the standard form for a categorical syllogism they sometimes look a little awkward)

All men are mortalSocrates is a manTherefore, Socrates is mortal

Concept

Evaluation: Valid vs. Sound Arguments

Arguments can still be valid even if the reasons are not actually true.

• An argument’s validity depends only on the support the reasons give to the conclusion.

This means you do not even need to know if the reasons are true or false to refute some arguments.

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Deductive Arguments

Valid

Invalid(all are unsound)

Sound

Unsound

Can you have a deductive argument that is valid but not sound?

Can you have a deductive argument that is sound but not valid?

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Concept

3 Quick Standards for Judging Validity/Cogency

Bulletproof: Deductive Validity: Can you think of any way the reason(s) could be true and the conclusion false (however unlikely)?

Very Strong:Proved Beyond a Reasonable Doubt: If the reasons are true (or otherwise acceptable) would a rational person have any real doubt about whether the conclusion is true (or otherwise acceptable?)”

Acceptable: Shown to be more likely than not On the Balance of Evidence: If the reasons are true, is the probability of the conclusion being true more likely than it not being true (given all available evidence)?

Concept

Evaluation: refuting bad arguments

Refutation: The act of showing some claim or argument to be false. Can be accomplished either by…

1. Attacking the inference• Show the that the reasons, even if true do not

support accepting the conclusion (i.e. Invalid)

2. Attack the premises• Show one or more of the premises to be false,

misleading or inaccurate (i.e. Unsound).

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Concept


Strategy 1: Attacking the Inference:

Two “simple” methods of proving Invalidity

1. The Counter-Example method 2. Identify fallacies

Concept


The Counter Example Method:

1. Isolate the arguments form by substituting letters for the terms contained in the premises.

2. While keeping the form of the argument intact substitute new terms for the old ones– (this is called a “substitution instance”)

3. See if you can construct a substitution instance with true premises but a false conclusion. If you can, the form of the argument is invalid.

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Example #1

If I get the flu then I will experience cough, fever and chills

I am experiencing cough, fever and chills

Therefore I have the flu

Example #1

If [I get the flu] then [I will experience cough, fever and chills]

[I am experiencing cough, fever and chills]

Therefore [I have the flu]

If p then q.q. Therefore, p

p = Its Mondayq = The Banks are Open

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Example #1

If it’s Monday then the banks will be open

The Banks are open

Therefore it’s Monday

If p then q.q. Therefore, p

p = Its Mondayq = The Banks are Open

Mistake: “Affirming the Consequent”


I am experiencing cough, fever and chills

Therefore I have the flu

Valid Form(Affirming the Antecedent)


I have the flu

Therefore I am experiencing cough fever and chills

If p then q. p. Therefore, q.

If p then q.q. Therefore, p.

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Concept


The Counter Example Method:

1. Isolate the arguments form by substituting letters for the terms contained in the premises.

2. While keeping the form of the argument intact substitute new terms for the old ones– (this is called a “substitution instance”)

3. See if you can construct a substitution instance with true premises but a false conclusion. If you can, the form of the argument is invalid.

Concept


Attacking the Inference:



Fallacies are common errors in reasoning. These invalid arguments are easy to spot with some training but often appear valid to the casual observer.

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Concept

Evaluation: Inductive Arguments

But what if we cant prove our conclusion is 100% certain, based on our premises?

Is our argument, necessarily a bad one?

Arguments that provide us less-than-certain conclusions are called inductive arguments.


Concept


Here are the terms we will be using for evaluation of Inductive arguments:

Strong – the premises make the conclusion more likely to be true

Weak—the premises do not make the conclusion more likely true

Cogent—strong, with true premises

Uncogent—either strong or weak, with false premises

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Inductive Arguments

Strong

Weak(all are uncogent)

Cogent

Uncogent

Concept


There are many different kinds of Inductive arguments, here are a few:

Prediction- an argument that proceeds from our knowledge of the past to a claim about the future

Argument from analogy – an analogy is drawn between a well known or uncontroversial case (X) and a lesser known case or controversial case (Y). If the two cases are similar enough, then a feature that is true of X may also be true of y.

Generalization – proceeds from knowledge of a selected sample to a general claim about the whole group.

Causal Inference – an argument that proceeds from the knowledge of a cause to a claim about an effect or vice versa.

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Concept

3 Quick Standards for Judging Validity/Cogency

Bulletproof: Deductive Validity: Can you think of any way the reason(s) could be true and the conclusion false (however unlikely)?

Very Strong:Proved Beyond a Reasonable Doubt: If the reasons are true (or otherwise acceptable) would a rational person have any real doubt about whether the conclusion is true (or otherwise acceptable?)”

Acceptable: Shown to be more likely than not On the Balance of Evidence: If the reasons are true, is the probability of the conclusion being true more likely than it not being true (given all available evidence)?

Concept


Attacking the Inference:



Fallacies are common errors in reasoning. These invalid arguments are easy to spot with some training but often appear valid to the casual observer.

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Formal vs Informal Fallacies

• All the examples we just reviewed are Formal Fallacies- the mistake can be detected just by looking at its form

• With Informal Fallacies we must look beyond the form to the actual content of the argument in order to detect the mistake in reasoning.

Irrelevant Reason Fallacy (a.k.a Red Herring)

• Arguer diverts the attention of the audience away from the subject to a different (sometimes related) subject. They either finish by drawing a conclusion from this different issue or by merely pretending the original conclusion has been established.

“Environmentalists complain about the dangers of nuclear power but unfortunately electricity is dangerous no matter where it comes from. Every year hundreds of people are electrocuted by accident.”

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Ad Hominem or “against the man”

• A debater commits the Ad Hominem Fallacy when he introduces irrelevant personal premises about his opponent. Such red herrings may successfully distract the opponent or the audience from the topic of the debate.

• “Pay no attention to what he says, he’s just a loud mouth conservative lunatic…”

• “You sir are a disgrace, you should be ashamed of yourself, I don’t know how you sleep at night…”

• “Why should I trust what you say about abortion, you are a Priest, you need to believe it’s a sin.”

Straw Man

• The Straw Man fallacy is committed when a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position.

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Appeal to Authority

• The fact that some authority says something is taken as proof of its truthfulness; this is to be distinguished from the word of an authority lending credibility to some claim.

• “President Richard Nixon should be re-elected because he has a secret plan to end the war in Southeast Asia”

• “my parents taught me that spanking is the most effective means of control”

Legitimate Appeals to Authority

We all need to trust the word of authorities to some degree. But in order for an authority to be credible, they must fulfill at lest 2 conditions:

1. They should have relevant expertise on the subject in question.

2. They are reporting the consensus position within their field, not simply their own opinion

Homework #1 Questions: http://www.memelyceum.com/documents/kchu228/ch1_fallacy_questions.pdf

http://www.memelyceum.com/documents/kchu228/ch1_fallacy_questions.pdf

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Post Hoc Fallacy

• Post hoc ergo propter hoc – “after this, therefore because of this”

• Example: “More and more young people are attending high schools and colleges today than ever before. Yet there is more juvenile delinquency and more alienation among the young. This makes it clear that these young people are being corrupted by their education.”

• When we assume that because event Y followed after event X, event X was the cause of event Y .

• “Correlation does not (necessarily) equal causation”

Appeal To Ignorance

• An appeal to ignorance is an argument for or against a proposition on the basis of a lack of evidence against or for it. If there is positive evidence for the conclusion, then of course we have other reasons for accepting it, but a lack of evidence by itself is no evidence

• There is no evidence against p. Therefore, p.

• There is no evidence for p. Therefore, not-p.

• “Absence of evidence is not evidence of Absence…”

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Examples Appeal To Ignorance

Atheist

• “A god cannot possibly exist—there is simply no evidence to suggest such a being is or ever has been active in the world”

Theist

• “Atheists have strived in vein to kill god, but Science cant disprove God…God is real”

Begging The Question

• Any form of argument in which the conclusion occurs as one of the premises, or a chain of arguments in which the final conclusion is a premises of one of the earlier propositions in the chain.

– More generally, an argument begs the question when it assumes any controversial point not conceded by the other side.

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Begging the Question = Circular Reasoning

“I think Chocolate Ice cream is the best because its my favorite!”

“The Governor must be innocent, because he would never do such a thing.”

God exists

How do you know?

The Bible Says He

does

Why should we trust the

Bible?

Because it is the word

of God

Slippery Slope

• A claim that some event must inevitably follow from another, usually as a chain reaction, when there is not sufficient reason to think that the chain reaction will actually take place.

“If we allow a ban on ‘partial birth’ abortion, then soon all abortions will become illegal.”

“If we allow a ban on assault weapons soon they will try to take away our hand guns as well”

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False Dichotomy/Dilemma Fallacy

• The fallacy of false dichotomy is committed when the arguer claims that his conclusion is one of only two options, when in fact there are other possibilities. The arguer then goes on to show that the 'only other option' is clearly outrageous, and so his preferred conclusion must be embraced (AKA - Forced Choice).

• Example: “Either I keep smoking, or I'll put on weight. I don't want to put on weight, so I better keep smoking.”(FF)

• Example: “Either your with us or your with the terrorists”

Complex Question

• Two or more questions are asked in the guise of a single question expecting a single answer given to both of them. The person questioned is led or trapped into affirming a false conclusion simply by answering the question.

Have you stopped plagiarizing your papers?

Is President Bush lying about 9/11 again?

Why is Barack Obama afraid of people seeing his birth certificate?

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Complex Question

Leading Question

“Tell us, on the night of April 9th did you see the defendant shoot the deceased?”

Straightforward Question

“What did you see on the night of April 9th?”

Hasty Generalization Fallacy

• To make a hasty generalization is to make a judgment about a group of things on the basis of evidence concerning only a few members of that group.

• Example: "I know someone who rides a scooter. You can't trust any of them."

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Hasty Generalization Fallacy

• Statisticians refer to this error as the failure to consider sample size. Accurate judgments about a group can be made on the basis of a sample only if the sample is sufficiently large and every member of the group has an equal chance to be part of the sample (Schick 140).

Appeal to Emotion

• An appeal to emotion is a type of argument which attempts to arouse the emotions of its audience in order to gain acceptance of its conclusion. Appeals to emotion are always fallacious when intended to influence our beliefs, but they are sometimes reasonable when they aim to motivate us to act (FF).

• “My opponent likes to use every chance he gets to drag our country’s name in the Dirt...I question his patriotism. I on the other hand believe America is the greatest country on earth.”

• “Marijuana is so dangerous, scientists don’t even know some of the ways in which it might be harmful.”

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Appeal to Majority/Bandwagon Fallacy

• Bandwagon arguments attempt to persuade by appealing to a popular sentiment, such as patriotism, loyalty, tradition, custom, etc. But a group thinking something is correct does not make it so. A proposition must be judged by evidence, not mere consensus.

False Compromise Fallacy

• An argument that assumes that with any debatable topic the truth must lie somewhere in the middle—regardless of the quality of reasoning presented for the arguments.

• Example: “I guess the truth is somewhere in the middle…”

• Example: “On the one side anti-tobacco crusaders make strong claims about how dangerous tobacco is. And the tobacco companies don’t admit that its dangerous at all…I think the truth is probably somewhere in between these two extremes.

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Appeal to AuthorityAd Hominem

Appeal to ignorance Begging the Question

Straw ManPost Hoc Fallacy

Name The Fallacy

Appeal to AuthorityAd Hominem Appeal to ignorance Begging the QuestionStraw ManPost Hoc FallacyHasty GeneralizationFalse DichotomySlippery SlopeAppeal to EmotionBandwagon Red HerringComplex Question

Name The Fallacy

Either we require forced sterilization of the third world peoples or the world population will explode and all of us will die. We certainly don’t want to die, so we must require forced sterilization.

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Name The Fallacy

Either we require forced sterilization of the third world peoples or the world population will explode and all of us will die. We certainly don’t want to die, so we must require forced sterilization.


Name The Fallacy

The position open in the accounting department should be given to Frank Thompson. Frank has six hungry children to feed, and his wife desperately needs an operation to save her eyesight.

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Name The Fallacy

The position open in the accounting department should be given to Frank Thompson. Frank has six hungry children to feed, and his wife desperately needs an operation to save her eyesight.


Name The FallacySome of the parents in our school district have asked that we provide bilingual education in Spanish. This request will have to be denied. If we did provide this service soon people would ask for bilingual education in Greek. Then it will be German, French, and Hungarian they are asking for. Soon after we might be asked to provide teaching in Polish, Russian, Chinese, Korean. We simply cannot accommodate all of them.

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Name The FallacySome of the parents in our school district have asked that we provide bilingual education in Spanish. This request will have to be denied. If we did provide this service soon people would ask for bilingual education in Greek. Then it will be German, French, and Hungarian they are asking for. Soon after we might be asked to provide teaching in Polish, Russian, Chinese, Korean. We simply cannot accommodate all of them.


Name The Fallacy

People who lack humility have no sense of beauty because everyone who possess a sense of beauty is humble.

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Name The Fallacy

People who lack humility have no sense of beauty because everyone who possess a sense of beauty is humble.


Name The Fallacy

Sylvia, I saw you shopping for wine the other day. Incidentally, are you still drinking excessively?

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Name The Fallacy

Sylvia, I saw you shopping for wine the other day. Incidentally, are you still drinking excessively?


Name The FallacyWe’re all familiar with the complaint that over 40 million Americans are without health insurance. But Americas doctors, nurses, and hospitals are among the best in the world. Thousands of people come from abroad every year to be treaded here. Clearly there is nothing wrong with our health care system.

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Name The FallacyWe’re all familiar with the complaint that over 40 million Americans are without health insurance. But Americas doctors, nurses, and hospitals are among the best in the world. Thousands of people come from abroad every year to be treaded here. Clearly there is nothing wrong with our health care system.


Name The FallacyOn Friday I took Virginia out to dinner. She told me that if I wasn’t interested in a serious relationship, I should forget about dating her. On Saturday I took Margie to a film. When we discussed it afterward over a drink, she couldn’t understand why I wasn’t interested in babies. Women are all alike. All they want is a secure marriage.

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Name The FallacyOn Friday I took Virginia out to dinner. She told me that if I wasn’t interested in a serious relationship, I should forget about dating her. On Saturday I took Margie to a film. When we discussed it afterward over a drink, she couldn’t understand why I wasn’t interested in babies. Women are all alike. All they want is a secure marriage.


Name The FallacyThe death penalty is the punishment for murder. Just as we have long jail terms for armed robbery, assault and battery, fraud, etc. and fines for speeding or traffic violations, so we must have a punishment for murder. Yes the death penalty will not deter murders any more than a speeding ticket will deter violating speed laws, but it is the punishment for such violation!

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Appeal to AuthorityAd Hominem Appeal to ignorance Begging the Question?Straw ManPost Hoc FallacyHasty GeneralizationFalse DichotomySlippery SlopeAppeal to EmotionBandwagon Red Herring?Complex Question

Name The FallacyThe death penalty is the punishment for murder. Just as we have long jail terms for armed robbery, assault and battery, fraud, etc. and fines for speeding or traffic violations, so we must have a punishment for murder. Yes the death penalty will not deter murders any more than a speeding ticket will deter violating speed laws, but it is the punishment for such violation!


Name The FallacyIf the advocates of prayers in public schools win on this issue, just where will it end? Perhaps next they will ask for prayers on public transportation? Prayers by government workers before they start their job each day? Or maybe mandatory prayers in public restaurants before starting each mean might be a good deal.

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Name The FallacyIf the advocates of prayers in public schools win on this issue, just where will it end? Perhaps next they will ask for prayers on public transportation? Prayers by government workers before they start their job each day? Or maybe mandatory prayers in public restaurants before starting each mean might be a good deal.


Name The FallacyAs corporate farms continue to gobble up smaller family farms, they control a larger percentage of the grain and produce raised in the US. Some have already reached a point in size where, if they should decide to withhold their grain and produce from the marketplace, spot shortages could occur and higher prices would result. The choice is to pay us family farmers now or pay the corporations later.

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Name The FallacyAs corporate farms continue to gobble up smaller family farms, they control a larger percentage of the grain and produce raised in the US. Some have already reached a point in size where, if they should decide to withhold their grain and produce from the marketplace, spot shortages could occur and higher prices would result. The choice is to pay us family farmers now or pay the corporations later.

PredictionAnalogyGeneralizationCausal Inference

StrongWeakCogentUncogent

What kind of Inductive Argument is this?

So far every cat that has been tested for self-knowledge in the laboratory has failed to recognize itself (as itself) in the mirror. It is likely that no cats have the ability for self-knowledge.

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Concept


But what if we cant prove our conclusion is 100% certain, based on our premises?

Is our argument, necessarily a bad one?

Arguments that provide us less-than-certain conclusions are called inductive arguments.


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Concept


Here are the terms we will be using for evaluation of Inductive arguments:

Strong – the premises make the conclusion more likely to be true

Weak—the premises do not make the conclusion more likely true

Cogent—strong, with true premises

Uncogent—either strong or weak, with false premises

Inductive Arguments

Strong

Weak(all are uncogent)

Cogent

Uncogent

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Pr(P)= Number of outcomes for which P happens

Total number of possible outcomes

Calculating Objective Probabilities

Pr(Ace of Spades)= 1/52 or 0.0192

Pr(~Ace of Spades) = 51/52 or 0.98

Probability of a Proposition Being True:

Pr(P) = 1 – Pr(not-P)

Remember: 1 = necessarily true0 = necessarily false

Calculating Objective Probabilities

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What are the odds that Chris is right?

Chris has long admired Jamie’s fit physique. Jamieworks out on a Roboflexexercise machine. Chrisconcludes that by purchasing a Roboflex they will be able to duplicate Jamie’s results.

Subjective Probabilities: do not measure the actual likelihood of a proposition being true. They measure the degree of belief (or the confidence) we have that the proposition is true.


Objective vs. Subjective Probability

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We always set our subjective probabilities according to our background knowledge (the information we have about the world). If our background knowledge changes, then we should adjust our degree of belief accordingly.

The Principle Principle: we want our subjective probabilities to be as close to the actual probability as possible.


Subjective Probabilities: do not measure the actual likelihood of a proposition being true. They measure the degree of belief (or the confidence) we have that the proposition is true, based on our background knowledge.


The Principle Principle: we want our subjective probabilities to be as close to the actual probability as possible.


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Increase DecreaseNo impact


Does the strength of the inference increase or decrease, as our background knowledge changes?

Chris has long admired Jamie’s fit physique. Jamie works out on a Roboflexexercise machine. Chris concludes that by purchasing a Roboflex they will be able to duplicate Jamie’s results.

Increase DecreaseNo impact


Does the strength of the inference increase or decrease?

Chris has long admired Jamie’s fit physique. Jamie works out on a Roboflexexercise machine. Chris concludes that by purchasing a Roboflex they will be able to duplicate Jamie’s results.

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How much should we adjust our degree of belief when we learn new information?

Bayes Theorem

Bayes Theorem in (not so plain) English

The probability our idea is true

=

How typical our explanation is

XHow likely the evidence

is if our idea is true

{ RepeatThe above } How likely the evidence

if our idea is falseHow atypical our explanation is }X+

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Concept


There are many different kinds of Inductive arguments, here are a few:

Prediction- an argument that proceeds from our knowledge of the past to a claim about the future

Argument from analogy – an analogy is drawn between a well known or uncontroversial case (X) and a lesser known case or controversial case (Y). If the two cases are similar enough, then a feature that is true of X may also be true of y.

Generalization – proceeds from knowledge of a selected sample to a general claim about the whole group.

Causal Inference – an argument that proceeds from the knowledge of a cause to a claim about an effect or vice versa.




Paying off terrorists in exchange for hostages is not a wise policy, since such action will only lead them to take more hostages in the future.

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Paying off terrorists in exchange for hostages is not a wise policy, since such action will only lead them to take more hostages in the future.




Jordan has lost at the craps table for the last ten throws of the dice. Therefore, it is extremely likely that he will win on the next throw.

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Jordan has lost at the craps table for the last ten throws of the dice. Therefore, it is extremely likely that he will win on the next throw.




Airline passages must go through a metal detector and/or pat down to make sure they do not bring any dangerous weapons on board. Similarly concert venues should use the same procedures to prevent alcohol and drugs from being carried into rock concerts.

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Airline passages must go through a metal detector and/or pat down to make sure they do not bring any dangerous weapons on board. Similarly concert venues should use the same procedures to prevent alcohol and drugs from being carried into rock concerts.





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Recommended Reading

How To Think About Weird Things: Critical Thinking for a New AgeByTheodore Schick Jr.& Lewis Vaughn

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Recommended Reading

Critical Thinking: An Introduction ByAlec Fisher

Recommended Reading

Thinking Fast and SlowByDaniel Kahneman

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Recommended Reading

A Concise Introduction to LogicByPatric J. Hurley

Recommended Reading

Thinking and DecidingByJonathan Baron

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