Chapter 11: Whom Do You Trust?

Criteria for evaluating testimony (pp. 109-116) The criteria provide inductive evidence that the person offering the testimony is reliable and limited evidence that the claim made is true. As is the case when dealing with observation statements, the criteria provide a basis for judging the inductive strength of an argument for the conclusion that the source of the testimony is reliable.

Criteria for evaluating testimony (pp. 109-116) (T1) Is the person offering the testimony generally reliable? If the source of the testimony is not known for telling the truth or for carefully examining the evidence for a claim, you have reason to question the reliability of the source. Hearsay evidence consists of rumors, what one person hears and says to another. Hearsay evidence generally should be considered unreliable. According to this criterion, you should grant greater credence to the New York Times or the Richmond Times-Dispatch than you would grant to the Weekly World News or the National Enquirer.

Criteria for evaluating testimony (pp. 109-116) (T2) Is the person offering the testimony trained in or does he or she have experience regarding the subject about which he or she is offering testimony? You assume this most of the time. That’s why you visit a physician to deal with your physical ills and why you call the helpdesk to receive aid with your computer. Experts sometimes make mistakes. So, if the person offering the testimony has the right background, this strengthens the reasons to believe the testimony, but it is not conclusive.

Criteria for evaluating testimony (pp. 109-116) (T3) Does the person stand to gain financially or in terms of status, prestige, or reputation by being believed? Does the person stand to lose financially or in terms of status, prestige, or reputation if he or she is wrong? Generally one should be suspicious if people who will stand to gain by being believed, and you typically do. Why do you distrust used car salespersons? When someone stands to gain by being believed, he or she has a conflict of interest. You’re never sure whether the person is telling you what he or she believes is the truth or whether he or she is making the claim only for the gain to be made. If you’re dealing with a professional, for example, a physician, he or she probably stands to lose more by being wrong than he or she will gain by being right. Professionals are paid for what they know, so the fact that they stand to lose if they’re wrong tends to suggest that, all things being equal, they should be believed.

Criteria for evaluating testimony (pp. 109-116) (T4) Is the testimony consistent with what you know from other equally reliable sources? For example, is it consistent with the testimony of equally qualified experts? As in the case of observation, consistency is extremely important. If a piece of testimony is inconsistent with that of an equally or better qualified person, it is wise to discount your belief in the truth of the testimony. What is known changes. So, in 1200 it was reasonable to accept the testimony that the earth is flat; it is not reasonable today.

Criteria for evaluating testimony (pp. 109-116) (T5) Is the person offering the testimony biased? As in the case of observation statements, bias can blind the person offering testimony to alternative interpretations of a piece of information.

Evaluating Research Sources (pp. 116-118) Be sure the sources are suitable and relevant . Evaluate the sources themselves. Evaluate the publisher. Check for documentation. Documentation usually shows that the author is well-informed.

Internet Sources (pp. 117-118) Academic journals and publishers have a process of review, so if something is published, it has received the (basic) approval of a few other scholars. There are no restrictions on what can be placed on a Web page. So, unless the source is known to be reliable on other grounds, whatever is published on a Web page should be viewed with skepticism.