If the full use of critical thinking involves the construction and evaluation of various forms of argument, the first step toward that skill requires looking at the building blocks of arguments, namely claims. We have considered the clear form that a claim must take; it is now time to turn to the claim's content, and how we know whether to accept or reject it.

When a claim arrives in the context of a developed argument, we will have to examine that whole argument before passing judgment on the claim. That will be the project of Part of Critical Thinking (Chapters 7 and following). But plenty of claims get asserted on their own, without backing from arguments, factual statistics, or anything else. To guide our judgment about such alleged information, we apply more elementary, more foundational principles.

Part 2 begins the process of determining how to treat isolated claims. In the present chapter, we look at those claims that purport to deliver information and measure them against two general standards of credibility. These standards do not work as all-purpose tests, but they do show how to begin assessing new claims that arrive without argument.

1. When a claim comes without any evidence or proof to support it, you have to decide whether to accept or reject the claim.
2. A reasonable bias exists against claims that deny direct observation.
3. A similar bias exists against claims that deny background information.
4. The reasonable acceptance of a claim also ought to depend on the credibility of its source. The credibility of people is usually a matter of their knowledge on one hand, and their truthfulness, accuracy, and objectivity on the other.
5. Credible sources can also include the news media and the Internet.
6. Advertising contains a number of unsupported claims whose credibility needs to be weighed with special care.

1. When a claim comes without any evidence or proof to support it, you have to decide whether to accept or reject the claim.

1. In the absence of an argument or other support, a claim has to be assessed on the grounds of credibility.
1. Credibility comes in degrees, giving you reasons to be extremely suspicious of what you hear, extremely eager to believe it, or any strength of acceptance in between.
2. The mistakes people make about unsupported claims are usually mistakes of believing something too easily, though it is also possible to go wrong in the opposite direction and treat claims more suspiciously than you should.
2. Claims and their sources both need to be credible.
1. Sometimes you disbelieve a perfectly reasonable-sounding claim because you judge (rightly or wrongly) that the person who tells it to you is untrustworthy.
2. Another claim may be so wild on the face of it that you won't believe it no matter who is speaking.
3. As a general rule: It is reasonable to be suspicious if a claim either lacks credibility inherently or comes from a source that lacks credibility.

2. A reasonable bias exists against claims that deny direct observation.

1. Direct observation makes a solid basis for knowledge, not easily made up for by other sources.
2. Still, several factors can render observations unreliable, and it is wise to consider such factors before rejecting a competing claim.
1. Observations depend on the conditions under which they are made.
1. What you hear in a noisy room is less reliable than what you hear in quiet, and so on.
2. Distractions, emotions, and fatigue can diminish the reliability of observations.
3. Observations that call for the use of measuring instruments are only as trustworthy as those instruments.
2. The power of observation can differ with people's expertise and experience.
3. Expectations often influence observation.
1. You are more likely to hear a knock at the door if you know someone plans to come.
2. Your emotional relationship to a person creates expectations about what that person is doing, and why, and how well.
3. You will call an action successful more often if you want it to succeed, and call it useful more often if it's something you want to do anyway.
4. An observation made in the past suffers from the same dangers of unreliability as memory in general.

3. A similar bias exists against claims that deny background information.

1. Background information includes all the general and specific facts we have learned through our lives, very often without being able to say where we learned them.
1. Together with direct observation, background information forms the ground against which to pose any new claim.
2. An assertion has more initial plausibility the more it fits with our observations or our background information.
3. We say that when two claims conflict, the burden of proof (see Chapter 6) lies on the one with less initial plausibility.
4. Since initial plausibility comes in degrees, we accept a plausible claim with different degrees of confidence.
2. No one possesses a perfectly broad and perfectly true body of background information; so this criterion needs to remain flexible.
1. Although a claim that directly conflicts with what we believe should not necessarily be accepted, it may provide a reason for us to double-check and try to confirm those old beliefs.
2. The greater our store of background information, the more reliable this test becomes. There is no substitute for knowing a broad range of things.

4. The reasonable acceptance of a claim also ought to depend on the credibility of its source. The credibility of people is usually a matter of their knowledge on one hand, and their truthfulness, accuracy, and objectivity on the other.

1. This principle even holds in cases of eyewitness accounts.
1. The quality of direct observation can depend on the observer's knowledge. Artists will be better than nonartists at remembering the color of someone's shirt.
2. Untrained observers are more likely to exaggerate their observations, partly because unusual features of a person or thing are more noticeable, and partly because reports of unusual features are more entertaining to describe.
3. Sharpening and leveling, the processes of exaggerating certain features of an experience and downplaying others, frequently distort an honest person's attempt to describe a person, a film, a book, etc.
4. Such exaggerations often follow from strong positive or negative feelings that people have toward the subject they are describing.
2. Since knowledge makes one more credible, expert knowledge makes for the most credible sources of all.
1. Experts have had the education, training, or experience to possess special knowledge on a subject.
2. Whether or not a matter concerns direct observation, the expert's claim should be accepted over the nonexpert's.
3. In order to avail ourselves of experts, however, we must know how to assess expertise.
1. Education is most important; this typically means what degrees a person may possess, but also where they received them. It may also mean some other form of training.
2. Experience counts heavily in making someone an expert, as long as it amounts to more than just many years at a job.
3. Accomplishments figure somewhere on this list below the first two factors: Remember that accomplishments should pertain to the subject on which the expert is speaking.
4. Reputation matters when it has been earned among reliable persons, usually other experts in the field. In considering reputation, we treat this community of peers as experts about who the experts are.
5. Closely related to reputation is one's position in a field of expertise—for example, a prestigious academic or scientific title.
4. Even after judging someone an expert, we need to remain aware that several factors can diminish that person's credibility.
1. Expertise in one subject rarely prepares a person to make reliable assertions about another subject. Make sure the expertise is relevant to the claim.
2. All sources, even experts, lose credibility when we have reason to suspect them of bias. Bias most often arises when the expert has a financial stake in an issue.
3. Experts lose some credibility when their claims conflict with those of another expert. Ask two further questions:
1. Does one of the expert opinions agree with what the majority of experts in that field believes?
2. Can we assess one of the experts as more authoritative or more biased than the other?
5. Because expertise doesn't guarantee infallibility, it is often wisest either to suspend judgment, or to accept a claim while still keeping an open mind about whether it could turn out false.

5. Credible sources can also include the news media and the Internet.

1. Newspapers, newsmagazines, radio, and television make good sources of information about contemporary events, but they need to be used carefully.
1. Talk radio at first appears to be a good alternative to traditional news sources, but it almost always represents specific political agendas that skew the information being presented.
2. As for the traditional news media, they vary in the depth and breadth of coverage they provide, and the selective presentation of facts can slant a story.
3. Most reporters get their information not through investigation but from governmental and private press releases and press conferences. So they depend on what their sources want to divulge, and on retaining good relations with those sources.
4. Being private businesses, the news media have to make a profit.
1. They need to take care not to offend or criticize their advertisers.
2. The media also can't lose their audience; so they tend to simplify issues and present more entertaining or sensationalistic stories.
2. The Internet has produced an unprecedented flow of informative claims. Depending on their origin, they may possess as much credibility as the claims of news media, or substantially less.
1. Commercial and institutional sources, such as Lexis-Nexis and other online services, belong in the same group as newspapers and newsmagazines.
2. Individual and group Web sites, on the other hand, may have any origin at all; you should consider them as reliable as any other stranger.

6. Advertising contains a number of unsupported claims whose credibility needs to be weighed with special care.

1. Remember that advertising sells more than consumer goods.
1. It may try to sell a political candidate or policy, a way of life, a habit.
2. Advertising acts by creating desires, and so uses every persuasive technique available to excite those desires.
2. The critical response to advertising rests on the question: "Does this ad give us a good reason to buy this product?"
1. This question fundamentally means: Will I be better off with the product than without it, or better off with the product than with the money it costs?
3. Many advertisements give no reasons why you should buy their product.
1. They try to associate pleasant feelings with the product, show it being used or endorsed by people we identify with, or show it in situations we would like to be in.
2. With the exception of ads that notify us of a product's existence when we already have reasons for wanting it (see E below), such advertisements never provide a justification for buying their product.
4. But just because some advertisements give reasons for their claims does not mean they give good arguments or reasons.
1. The typical reason found in an advertisement is vague, ambiguous, misleading, or exaggerated.
2. Moreover, these reasons come unsupported: We have no way of knowing whether to believe the advertised claim.
5. One kind of advertisement provides a justifiable reason to buy its product.
1. This occurs when the ad tells you of the availability of a certain product you already want, or its availability at a price you can afford.
2. Such ads derive their justification from whatever justification you antecedently have for wanting the product.