¶ … role in any process of enquiry that is undertaken to arrive at the truth, a sound argument or an objective opinion. In fact, good critical thinking is conceptualized as: distinguishing between verifiable facts and value statements; distinguishing relevant from irrelevant reasons; determining the factual accuracy of statements and the credibility of sources; identifying ambiguous statements and unstated assumptions; detecting bias; identifying logical fallacies; and determining the overall strength of an argument or conclusion (Duplass & Ziedler, cited Beyer, 2002). Thus, it is evident that learning to recognize and avoid logical fallacies is vital to the process of critical thinking. It is the objective of this paper to discuss the significance of three such logical fallacies: personal attack; two wrongs make a right; and red herring. The fallacy of personal attack also referred to more formally as argumentum ad hominem, is a popular tactic that is often used to deny the logical force of an argument by attacking the person who advances the argument. This is usually done by deploying one of three variants: (1) abusive, (2) circumstantial, and (3) tu quoque. The first, or abusive variant, is a head-on personal attack, which undermines the opponent's credibility through portraying her or him as dishonest or incompetent. The second, or circumstantial variant is a tactic that points out special circumstances, which suggest that the opponent's arguments are tailored to protect her or his self-interests. The third, or tu quoque variant, uses past precedents to point out an inconsistency in the positions...

This may be an inconsistency in the standpoint the opponent defends or attacks, or a discrepancy between a standpoint verbally expressed by the opponent and other behavior. The latter is a tactic that is often used when the accuser is guilty of the same practices criticized in the opponent (Blair et.al., 1996, p. 65-66).
Although there is undoubtedly some merit in verifying the source credibility of arguments, the fallacy of ad hominem is significant in critical thinking, as it is important that arguments are first evaluated independently. Indeed, allowing diversionary tactics to sway one's focus or judgment could lead to faulty evaluation. For instance, in business negotiations or pitches, an opponent will often deploy ad hominem tactics to create doubts about competitors' credibility, competency, or claims. In fact, this is known to happen pretty often in highly competitive industries such as Information Technology: "...suggestions...BAPCo organization favoring Intel.... It seems to me that if we are trying to determine, as scientifically as possible, whether a given benchmark accurately reflects real world performance then we should only use techniques and evidence that will allow us to make that determination and forgo the ad hominem attacks on companies...." (Kent, 2001)

The "two wrongs make a right" fallacy occurs when an immoral action is justified by pointing to another wrong action. When the other wrong action is of the same type as the one committed by the accuser, it is sometimes classified as the sub-fallacy, tu quoque. This sort of…