A course for a critical thinker!![分享] 第一课

mike1999

从今天开始我将把握每天学习的course的精华部分贴上来。希望大家一起学习！
第一课Introduction to Statements (or Claims)
Sentences that can be true or false--the vast majority of all sentences in critical thinking--are called statements or claims. Note that you don't need to know whether a statement is true or false, just that it has the form of sentence that can be true or false. We may never know the truth of such sentences as "Before he died, Elvis was thinking of becoming a vegetarian" or "The universe is younger than its oldest galaxies"; we may not even completely understand them. But as long as they have the possibility of being true or false, such sentences are statements.

We can further categorize statements by three qualities:

whether they are verifiable, evaluative, or advocatory claims;
whether they are specific or, if non-specific, whether the qualification strengthens or weakens the claim;
whether they serve as conclusions, premises, or support in an argument.
In this section, we will be focusing on the first two qualities only.
              Qualified and Specific Statements
Specific claims contain or imply language or figures of an exact nature:

45% of the people surveyed supported the reforms.

One-third of the investment has been lost.

This marked the first time that India successfully orbited a satellite.

In those three sentence, "45%," "one-third," and "first" represent specific information. Such statistical statements are powerful and persuasive expressions in an argument, but they are also easy to attack, because a single example to the contrary is sufficient to refute them. The most common specific statements are universal ones, in which the figure involved is either "100%" or "0%," usually expressed by words such as always, never, all, none, everyone, no one, and so on.
Non-specific claims are ones in which no specific number is cited; as a result, they are often more difficult to attack. Consider the following examples:

49% of those casting ballots voted for Kennedy.
Approximately 49% of those casting ballots voted for Kennedy.
More than 49% of those casting ballots voted for Kennedy.
Less than half of those casting ballots voted for Kennedy.
Kennedy received more votes than did Nixon.
Only the first example above is a specific claim. The second qualifies that specific claim with the word "approximately," making the statement weaker but harder to disprove. The last three examples are all comparative statements, a type of qualification that operates by comparing the subject of the statement with something else (49% of the votes vs. "more than 49%," half the votes vs. "less than half," the votes for Kennedy vs. the votes for Nixon). Comparative and other non-specific claims are usually harder to disprove than specific claims, but not always; often, they are also more effective in an argument.

A claim with a modifier is considered qualified whether it is specific or non-specific. Non-qualified claims have no modifiers at all: "The investment has been lost" or "Kennedy received votes." These sound universal, but may not be.



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Note that many claims appear to be specific, but are usually intended to be non-specific. Consider these examples:

Jacques is a good boy.

Americans are rich and well-educated.

Mercedes are reliable cars.

All of these examples convey an implied "all" or "always." But even if we said, "Jacques is always a good boy," we wouldn't be surprised to find out about the time Jacques wasn't good. And though Americans may be rich and well-educated as a group, compared to many other peoples in the world, we surely recognize that there are many Americans individually who are either not rich or not well-educated. Generally speaking, apparently specific claims should be understood as non-specific when they deal with personal behavior or group attributes because humans (and other organisms) are individually inconsistent and collectively diverse. To some extent, this is true of other populations, including manufactured items like automobiles. We understand that "Mercedes are reliable cars" doesn't mean "100% of Mercedes are reliable cars." Yet "Mercedes have aluminum-head engines" may well mean "100% of Mercedes have aluminum-head engines"; and (most interestingly) we may be willing to put "all" in front of the statement, "Mercedes are expensive cars," even though we know that a heavily damaged Mercedes can be bought for only a few dollars. The point here is that, sometimes, context and convention may affect our understanding of even simple statements. The job of a critical thinker is to understand the statements as they were meant, rather than insisting on a purely literal construction.

mike1999

第二课：
Statements of Verification, Evaluation, and Advocacy

Fact and Opinion. In critical thinking, the difference between what are commonly called "facts" and "opinions" is not great--if, in fact, it exists at all. Both "facts" and "opinions" can be used to support arguments, and sometimes strong expert "opinions" can outweigh weak or inconsistent "facts." Indeed, considering that much of what we know about the physical sciences is based on hypotheses--that is, opinions that cannot be confirmed--you might wonder why we bother distinguishing between "fact" and "opinion" at all.

Verification and Evaluation. A more important distinction for critical thinking is between claims that are thought to be verifiable, and those that are presented as evaluative. In this sense, verifiable claims are those that can be confirmed either by observation or by reference to established sources, such as books. Evaluations are statements of taste and interpretation. Notice that opinions can be expressed sometimes as statements of verification and sometimes as statements of evaluation. Consider the following claims:

"Willa thinks that's a shade of blue."
"Willa thinks that's a lovely shade of blue."
"That's a shade of blue."
"That a lovely shade of blue."
The first two are clearly opinions, but they are expressed as statements of verification, because the issue is whether that is what Willa thinks, not what the color is. The third one is also a statement of verification, because (for most people) "blue" is something ascertainable by observation. But the fourth claim is a statement of evaluation, because what is "lovely" is a matter of taste. And it doesn't matter whether the claim is true or false--that is, a false statement of verification is not a statement of evaluation. All four of our examples can be false--Willa might think otherwise, for the first two, and the color might be red, for the second two--but they are nevertheless three statements of verification, followed by a statement of evaluation.

Advocatory claims are a little different from verifiable or evaluative claims, in that the latter discusses what was, is, or will be, while the former describes what ought to have been or ought to be. Thus, "Ike is a free man" is a claim of verification, "Ike is a good man" is a claim of evaluation, and "Ike ought to be a free man" and "Ike should be a good man" are both advocatory statements. Advocatory claims usually include the word "should" or "ought" (though not all claims with "should" or "ought" in them are advocatory). The advocatory form is used for statements about morality, ethics, duty, and so on.



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The point of categorizing statements into specific and qualified, on one hand, and verifiable, evaluative, and advocatory, on the other, is to understand better the arguments in which they appear. We have already seen that specific claims are the most persuasive but also the most easily refuted. Correctly identifying such statements helps to indicate what needs to be done to attack and defend an argument. Knowing if a statement is one of verification, evaluation, or advocacy helps ensure a consistency of argument, because if the conclusion is a statement of verification, it must be supported by at least one premise that is a verifiable claim; and so too with conclusions of evaluation and advocacy.

mike1999

第三课：very important
Types of Statements and Conversions
Statements can be classified into four types or patterns, as follows:

All A are B.
No A is B.
Some A are B.
Some A are not B.
Of course, the language used in arguments is much more complex than those four statements. As a result, part of your task as a critical thinker will be to restate claims to fit one of those patterns, composed of two terms subject and complement) connected by a state-of-being verb (some form of "to be," such as "is," "are," "were," "will be," and so on). The restatement can reduce the complexity of the original sentence as much as you like, providing it creates no change or confusion in the meaning. "All horses eat hay," for example, can be restated as "All horses are eaters." This may sound a little odd, but it is important to replace verbs expressing action with state of being verbs.
Take the claim, "I like good food." Does that mean "Everything I like is good food," or does it mean "All good food is something I like"? The correct restatement is the latter, "All good food is something I like." This has the form, "All A are B," where "good food" is A and "something I like" is B. But had we failed to convert the original verb, "like," to a state-of-being verb, we might have mistakenly assigned "I like" to A and "good food" to B, producing the equivalent of "Everything I like is good food," which we have already determined to be an erroneous restatement.

As the previous example suggests, accurately expressing the sequence of terms in a statement is often very important. Two of the four types of claims, however, can switch the order of their terms without altering their logical implications. These two valid conversions are:

No A is B is equivalent to No B is A.
Some A are B is equivalent to Some B are A.
In other words, "No deciduous trees are evergreens" is equivalent to "No evergreen trees are deciduous," and "Some apples are red" is equivalent to "Some red things are apples." These may sound obvious, but language can be confusing, so remember that those are the only two possible valid conversions.

"Only A is B" is equivalent to "All B is A,"
"No A is B" and "No B is A" are valid conversions
Some A are B is equivalent to Some B are A.
"Some A are not B" cannot be converted to "Some B are not A,"
And "All A are B" cannot be converted to "All B are A,"

mike1999

第四课：
Introduction to Vagueness and Ambiguity
Though seemingly synonymous in common usage, vagueness and ambiguity are entirely different but very important problems in critical thinking.

Definitions

A word or phrase is said to be ambiguous if it has at least two specific meanings that make sense in context.
A word or phrase is said to be vague if its meaning is not clear in context.
The difference, then, is a clear one: If Montgomery doesn't know what is meant by a phrase, then that phrase is vague to him. If Montgomery doesn't know which of two or more specific meanings is intended, then it is ambiguous to him.
Consider this line from a help-wanted ad: "Three-year-old teacher needed for pre-school." Most people think this is funny, because the ad seems to be seeking a teacher that is three years old. But the phrase is ambiguous: the ad is actually seeking a teacher for three-year-old pre-schoolers. The phrase is ambiguous because two specific and distinct meanings can be applied to it in the given context. (Notice, however, that the level of ambiguity is dependent on the terms involved. "English teacher needed for pre-school" would normally not be considered ambiguous, though in certan contexts it could be understood to be seeking a teacher from England. But how about "Vietnamese teacher needed for pre-school"?)

Vagueness, though, is a different problem. "Nurse needed for pre-school" is vague because there are many kinds of nurses, and the same job is certainly not open to them all: registered nurses, practical nurses, wet nurses, nannies, and so on. The problem is that the word "nurse" has many meanings, and so the ad's usage is vague. The more details that are supplied, the less vague a phrase will be. "Registered nurse needed for pre-school" would be less vague, "Registered nurses with pediatric experience needed for pre-school" would be even less so. Notice that, for almost every word or phrase, you can probably imagine some situation in which it would be vague. We can tolerate a certain level of vagueness in language, but it is the job of a critical thinker to minimize vagueness by ensuring the language used is appropriate for its context--that is, for its subject and its audience.

greenfish

tks

mike1999

第五课，非常重要。非看不可！
Premises, Conclusions, and Support

An argument is a series of statements used to persuade someone of something. That "something" is called the conclusion or main claim. The first job in analyzing any argument is to identify its conclusion. One way to identify conclusions, or other parts of an argument, is to look for their indicators.：
The language in which an argument is presented often contains words or phrase to help identify its parts, especially its premises and conclusion. These words and phrases are identifiers of the function played in the argument. Unfortunately, identifiers are only as precise as the persons using them, and both the individual making an argument and the one evaluating it are liable to make mistakes by inexact or sloppy use of identifiers. Since the purpose of an argument is to communicate an idea clearly, the careful use and interpretation of identifiers is an important skill for critical thinking.

The following are some of the most common premise and conclusion identifiers:

Premise identifiers:         Conclusion identifiers:
since         therefore
for         thus
because         so
supposing that         as a result
given that         consequently
assuming that         we can conclude that


These are only a few of the words and phrases commonly used to identify premises and conclusions. In addition, keep in mind that:

some of these words can also appear within the context of an argument, but without indicating an inference. "So," for example, has several meanings, only one of which is a synonym for "therefore."
sloppy usage may produce confusing identifiers. A common answer to the question, "What would you think if the sky suddenly clouded up and turned very dark," is "I would assume it was going to rain." Yet "it is going to rain" here is a conclusion, not an assumption or premise.
"if" and "then" are often used to identify premises and conclusions, respectively. However, "if" and "then" are also used to introduce the two halves of a conditional premise. In either usage, "then" is sometimes omitted; and it has other meanings, as well.
an identifier may not immediately precede or follow the word or phrase whose function it is indicating. For example, in the sentence "Thus, whenever the sun rises, the rooster crows," there are two claims: a premise, "the sun rises," and a conclusion identified by "thus" (but not immediately following it), "the rooster crows."
in cases where there are no identifiers, the most frequent order is conclusion first, followed by one or both premises. If both premises are given, they are often conjoined with "and" or "but." For example, "I like Mozart. I like most classical composers, and Mozart was a classical composer."

Premises are statements that directly support the conclusion. A simple argument has two premises and a conclusion; a more complex argument may contain many claims, but these can always be divided up into groups of three--two premises and a conclusion. In an argument, the conclusion is only supported by its two premises, but each premise itself can be supported in a number of ways:

Supporting arguments. A supporting argument is one which has as its conclusion the same statement as the premise being supported. All premises can be supported in this way, but such supporting arguments are often not stated. A special type of supporting argument is a definition, and while these, too, are usually unstated, at times it is necessary to define a term because either the term itself or the particular denotation being used is unusual.
Assumptions. Eventually, all support for premises can be traced back to a set of beliefs which the person making the argument considers to be self-evident, and therefore not in need of further support or analysis. These may be called assumptions, presumptions, suppositions, or, in certain situations, postulates and axioms. Such assumptions serve as the premises for supporting arguments and, in general, any premise can be called an assumption.
Evidence. A premise can be made more acceptable when it supported by various kinds of evidence: statistical studies, historical information, physical evidence, observations, or experiments, eyewitness accounts, and so on. The relative strength of evidence is determined by how reliable a person believes it to be. Almost no evidence is beyond dispute--we might challenge the methodology of a study, the accuracy of the information, the manner in which physical evidence was collected, and the eyesight or motivation of an eyewitness. And remember that the evidence only supports the premises--evidence cannot be an argument itself.
Authority. Sometimes, we are not in a position to judge supporting evidence for ourselves: there may simply be too much of it, or it may be too technical in nature, or it may not be directly available to us. In those cases we often rely on the judgments of others, authorities whom we believe to be more likely to come to an accurate evaluation of the evidence than we are ourselves. Though we tend to think of such expertise in scientific, medical, or other scholarly fields, authority in arguments can also come from religious teachings, folk wisdom, and popular sayings--anything or anyone that we accept as somehow able to reach a more accurate evaluation. The relative strength of an authority in an argument depends on how willing a person is to accept the judgment of that source, but even in the strongest of cases, use of an authority merely supports a premise, and does not make an argument by itself.
Explanations and anecdotes. Sometimes, we are more willing to accept a premise if we are given background information or specific examples. Such explanations and accounts are not given the importance of evidence or authority in an argument. Anecdotal evidence, for example, is by definition less statistically reliable than other sorts of evidence, and explanations do not carry the weight of authority. But both anecdotal evidence and explanations may affect our understanding of a premise, and therefore influence our judgment. The relative strength of an explanation or an anecdote is usually a function of its clarity and applicability to the premise it is supporting.
The various sorts of support for a premise--supporting arguments, evidence, authority, and explanations and anecdotes--interact in what we might call a hierarchy of support or evidence, in which one sort is given priority over another. In a murder trial, for example, the prosecution is usually based on the assumption that the jury's hierarchy of evidence will have at the top physical evidence (fingerprints, blood samples), especially as explained by technical authorities (forensic pathologists, ballistics experts), followed by eyewitness accounts, then by other sorts of authorities (psychologists, sociologists), and finally by explanations and anecdotes (character witnesses, personal histories). If the prosecution is right, their strong physical evidence and eyewitness accounts will outweigh the defendant's character witnesses, because of their relative placement in the jury's hierarchy of evidence. However, because that hierarchy is determined by each individual on a case-by-case basis, one can never be totally sure how any one piece of support will be accepted.

Facts and Opinions. In the section on statements, we distinguish between three kinds of claims: verifiable, evaluative, and advocatory. Generally speaking, evidence takes the form of a verifiable statement, and authority takes the form of a evaluative statement. We have avoided using the terms "fact" and "opinion," in part because of the strong connotations these words carry. People tend to think that "facts" are much more reliable and convincing than "opinions," yet many "facts," such as statistical surveys, scientific measurements, and historical events, are ultimately based on "opinions." Thus, the difference between verifiable evidence ("The victim's blood was found on the suspect's clothes") and evaluative authority ("According to my analysis, the sample taken from the suspect's clothes matches the victim's blood type), is often more a matter of presentation than of fact vs. opinion.

今天的内容就这么多。原来每刻都有一些练习，可是都有链接，不好粘。等我以后总结出来了再粘吧。内容比较多，看起来很累。我也看得很累。慢慢来。这前面是基础。后面的东东才难。实在不行大家全当练写作argument作文好了。我给大家看看整个结构：
The Basics

Parts of an Argument
Statements
Statements and Conversions
Universal Statements
Vagueness and Ambiguity
Premises, Conclusions, and Support
Inference Identifiers
Exercises for Identifiers
Validity, Truth, and Soundness
Basic Relations
Conjunctions and Disjunctions
Exercises for Conjunctions and Disjunctions
Options
Exercises for Options
Analysis of Arguments

Introduction to Inductive and Deductive Reasoning
Inductive Arguments
Causal Arguments
Exercises for Causal Arguments
Deductive Arguments
Exercises for Deductive Arguments
Conditional Arguments
Exercises for Conditional Arguments
"Only" in Conditional Arguments
Exercises for "Only" Conditionals
Conditional Chain Arguments
Exit Quiz for Conditionals
Universal Syllogisms
Exercises for Universal Syllogisms
Non-Universal Syllogisms
Exercises for Non-Universal Syllogisms
Exit Quiz for Syllogisms
60 Deductive Review Exercises
Fallacies and Non-Rational Persuasion

Fallacious Appeals
Misdirected Appeals:
Appeal to Authority  Appeal to Common Belief
Common Practice
Two Wrongs  Indirect Consequences
Wishful Thinking

Emotional Appeals:
Appeal to Fear Appeal to Loyalty
Appeal to Pity Appeal to Prejudice
Appeal to Spite Appeal to Vanity

Exercises for Fallacious Appeals
Generalizations
Ad Hominem Attacks
Exercises for Ad Hominem Attacks
Other Common Fallacies
Post Hoc Reasoning Straw Man
Burden of Proof Circular Reasoning
Loaded Question False Dilemma
Unfair Fallacies: False Compromise
False Equity

Exit Quiz for Fallacies
40 Fallacy Review Exercises


很吓人，不过要使大家掌握了这些东西，用美国人的逻辑思维加上一定的阅读能力，逻辑拿高分肯定没有问题。我的目标是争取错一个以内。我们一起努力！！

[此贴子已经被作者于2003-6-9 14:04:31编辑过]

albert

great job! mike, go on!
I almost miss your these important post!

mike1999

第六课：Validity, Truth, and Soundness

The first rule in evaluating any argument is never bother to disagree with a conclusion, because if you find nothing wrong with its form (or how the argument is made) and nothing wrong with its content (or the assumptions on which the argument is based), then you must accept its conclusion. As a result, to challenge an argument, you must challenge either its form or its content, not its conclusion directly. Because we can always evaluate the form of an argument, but not always its content, the process of analyzing an argument usually begins with its form.

Validity. When the form of an argument is acceptable, that is, when its premises and conclusion are in the proper relationship, we say that the argument is valid. A valid argument, then, is one that is in an acceptable form; and invalid argument is one in an unacceptable form. Rules for determining the validity of an argument are given in the sections on inductive and deductive reasoning. If an argument is found to be invalid, all judgment of its must be suspended because, to be acceptable, an argument must be valid. The conclusion of an invalid argument is not necessarily wrong; because of the invalidity, there is simply no way to evaluate that argument.

Truth. If, however, the form of an argument is found to be valid, then the content of its premises must be evaluated, to determine if they are true or false. A true premise is one that you believe has or can be verified, or is self-evident, in the case of a verifiable statement, or has or can be justified, or is self-evident, in the case of an evaluative or advocatory statement. The verification or justification usually comes in the form of support, such as evidence, expert opinion, and supporting arguments.

As a general rule, in judging premises and their support, you should accept as verifiable or justifiable all claims that follow these three rules:

They are not in conflict with what you know or understand to be true.
They do not require you to believe or accept other unsupported elements that are in conflict with what you know or understand to be true.
They bear the proper burden of proof.
Burden of Proof refers to the sense you have, in any dispute, of how much each side needs to prove in order to win your agreement. Sometimes, this burden of proof is an established rule: in the United States, for example, the criminal court system operates on the rule that a person is innocent until proven guilty, which means that the prosecution carries all of the burden of proof; if the defendant is not proven guilty, then he or she should not be convicted of a crime, even if the defense cannot or does not prove him or her innocent of that crime.
Generally, by initiating a claim one takes on a greater degree of the burden of proof than the same position would warrant otherwise. If, for example, Warren said, "California became a state in 1850," he would be expected to offer more proof for his position than if someone else said "California became a state in 1851," and Warren disagreed. In an easily verifiable case like that, the burden of proof is almost even, so the person making the claim is usually expected to support it first.
In most arguments, however, it is usually the side that supports altering or rejecting the status quo--the current beliefs, practices, and information--which has most of the burden of proof. The more controversial the matter, generally speaking, the more evenly is the burden of proof shared by all sides; and the more extreme or unusual one side of an argument is, the greater its burden of proof. In such extreme cases, initiating the claim is normally insufficient to offset the burden of proof. Thus, if Aziza says, "I don't believe in ghosts," we might be willing to accept her claim without any support, even though she has initiated it, because the burden of such an argument would be carried overwhelmingly by the side that supports a belief in ghosts.
Intentionally shifting the burden of proof, in order to avoid offering support for one's premises, is a logical fallacy.
Consider the following arguments:

1.I can prove there is life on Mars. Samples of Martian rocks show evidence of the kind of chemical reaction that can only involve a living organism.
2.I can prove there is life on Mars. Spectroscopic analysis through the Hubble telescope has revealed a purplish area on the Martian surface, and according to Mozyritzski's Second Law, that purplish area must be associated with living organisms.
3.I can prove there is life on Mars. A spaceship filled with Martians abducted me last night.
4.Prove there is life on Mars? Can you prove there isn't?
The fourth one is the easiest to deal with: at the minimum, a claim of life on Mars carries some of the burden of proof, and therefore has to be substantiated. The fact an opponent cannot disprove the claim is insufficient for the claim to be accepted; it must be proved. The third argument makes the same claim and does support it, but the support (that the speaker was abducted by Martians) requires you to believe something else that is itself unsupported and even more unusual. The second argument is similar to the third, although it may be easier to accept Mozyritzski's Second Law (whatever that is) than Martian abductors; we can reject Martian abductors without further consideration, but to accept or reject an argument based on Mozyritzski's Second Law, we first need to find out what it is, whether it applies in this case, and how accepted it is generally. The first argument was, in fact, made by scientists in 1996, and it is certainly the most creditable of the four examples here. That "chemical reaction" may be no more verifiable than Mozyritzski's Second Law, but it is more accessible. (In fact, other scientists soon disupted the claim.) So, as presented above and without further support, those four arguments appear in descending order of their acceptibility. Yet even the claim, "There's no life on Mars," would carry some of the burden of proof, if for no other reason than someone initiated it.
Soundness. Finally, if an argument is valid and its premises are true, it is termed a sound argument, and its conclusion must be accepted. In many cases, however, there is insufficient reason to find the premises of a valid argument totally true; the more complex the argument, the less likely that it will be considered undeniably sound. In such cases, we often talk of the "relative soundness" of an argument by describing it as strong or weak. A strong argument is valid in form, and with premises and support that make a compelling case for its acceptance. A weak argument is also valid in form, but its premises and support do not compell their acceptance.

renprince

helpful and tks