Jeffrey Koperski's Zygon article “Two Bad Ways to Attack Intelligent Design and Two Good Ways” (2008) charges those who attack Intelligent Design (ID) with committing two common fallacies as his first “bad way” to attack ID. The fallacies in question are “stereotyping” and the infamous “ad hominem.” Koperski's objection that stereotyping of the ID proponent occurs far too often is a good one, but he either conflates or fails to tease out the relevant differences between the creationist on the street and the ID theorist putting forth an alternative, explanatory model of the origin of species to evolution, or more specifically, Darwinian natural selection. In the same vein, confusion over what constitutes an ad hominem fallacy rather than a legitimate ad hominem argument also occurs far too often, and I claim that Koperski makes this mistake: he conflates the ad hominem argument and the ad hominem fallacy as a single “bad way.” By doing this, his misses out on one legitimate “good way” to evaluate the claims of ID theorists. In this paper, I explain Koperski's main concerns with certain kinds of evaluation (what Koperski calls attacks) of ID; how Koperski has conflated the two types of ad hominem arguments (fallacious or not); and how the objections to ID theorists are ad hominem, although the good—that is, relevant—kind. Thus, they aren't fallacies to be resisted and rejected immediately, as Koperski claims, but accepted as legitimate objections and a “good way” to evaluate ID. I should add that the arguments in support of the other ways that Koperski presents in his 2008 paper are worth reviewing for those who are interested in the wider debate, but I will not address them here. I believe his two “good ways” to evaluate ID are cogent, but I am less convinced by his arguments against the second “bad way” concerning methodological naturalism as a shaping principle and the demarcation problem. As important as these arguments are, I believe Koperski's cursory introduction and swift rejection of ad hominem argument as a way to evaluate ID warrant a longer review.

Koperski begins by claiming, “As a philosopher of science, I am mainly interested in the arguments” (Koperski 434). And a few sentences later, he writes, “The first (“bad way” argument) is a relatively simple exercise in informal logic (nonvalidity related issues). ID critics often use fallacies that should be familiar to any logic student” (434). What I find particularly interesting in these two short statements is that Koperski, I would hope, is not mainly interested in the arguments, but is only interested in the arguments. What he presents on behalf of ID critics in this section, however, isn't a particularly charitable interpretation of ID critics’ objections (which I address following). Second, claiming these fallacies are simple and should be familiar to any students who have taken a logic class fails to take seriously the principle of charity that all evaluators of argument should abide by and is, thus, an instance of an abusive, fallacious assurance. Charity is a principle that all logic students should be taught so they don't present their interlocutor's arguments in a way that is weaker than it actually is—that is, committing the straw man fallacy. This is exactly what Koperski has done, although I think unintentionally, in his brief treatment of this “bad way” of evaluating (Koperski would use attacking ¹ ) ID.

When evaluators are confronted with multiple ways to interpret some view, using the version that is the least charitable is intellectually uncharitable at best and intellectually dishonest at worst. The vast majority of ID critics—and all the respectable ones—are quite familiar with ad hominem fallacies, and so we should ask: might the ID critics be doing something other than just name calling and committing fallacies? The answer is a clear yes, and in the final section on how relevant ad hominem arguments work, I explain why, but at this point we need to be clear about what Koperski is claiming and how he argues for those claims.

In the section Motives and Associations, Koperski presents his claims that ID critics are committing the ad hominem fallacy. He presents three types of cases that give rise to charges of ad hominem attacks that are unjustified. I shall call the three cases “Categorical Confusion,”“Committed Marx Analogy,” and “Validity Equivocation.” In each example, I believe Koperski has made a mistake in characterizing the argumentative situation between the proponent and opponent of ID.

Categorical confusion:  In the case of categorical confusion, Koperski comments on the ambiguous or vague nature of the terms creationism and evolution. He has a point. He writes, “As one of the members of our biology department defines it, all theists are creationists. But that cannot be correct. Kenneth Miller is a well‐known ID critic and a Roman Catholic” (434). What has happened here is that Koperski confuses the “A form” categorical statement “All S are P” for its converse “All P are S” and then makes an inference that is unjustified and formally invalid. The point ID critics make—and one I believe is relevant—isn't that all theists are ID theorists but that all ID theorists are theists. The point is brought home by the fact that even Michael Behe, a biochemist and ID supporter, is a theist. Although Behe is a scientist who accepts some of the facts of evolution, it isn't sufficient to shield him from certain kinds of criticisms. No one doubts that there are theists who don't support ID, but the point is that all ID theorists—even the scientists who support ID—are theists (generally fundamentalist Christians), but we will come back to the relevance of ID scientists in the final section.

Committed Marx analogy:  Koperski begins this section with the following: “Regardless of what labels we use, the question of motivation appears to be the key issue in this debate” (435). Koperski couldn't be more right in this assertion, but then he moves on to discussing the “Wedge Strategy” of the Discovery Institute and makes an analogy with a Marxist professor he had in graduate school. The wedge strategy, according to an anonymous source at the Discovery Institute, is to get credentialed scientists hired into universities who will then promote ID. Koperski then presents the following analogy:

One of my professors was a committed Marxist. As the faculty advisor for a socialist student group, he admittedly was interested in becoming a professor in order to promote his political views. He hoped to persuade students to do likewise. Now consider the articles he had published in scholarly journals. Did the fact that he had a political motivation affect the strength of his arguments in those papers? Should the editors of those journals have taken his political agenda into consideration? (435–36)

The answer to that rhetorical question is “Of course not!” will return.We might ask: is this analogy a good one? Are biology, a science, and politics, a social science, similar enough to be compared in this way? Another way to think of it is, are biological theory and political theory held to the same standards of truth, explanatory power, and predictive success?

There are at least two points to make here. First, there is a relevant false analogy: scientific explanations aren't the same as political explanations. The former are supposed to explain how things occurred and worked, whereas the latter have a normative component that good science is supposed to lack even when you allow for theory‐laden aspects of scientific explanations. If, however, one thinks the ID movement is a political movement, then as a political movement the analogy seems to be spot on. Just as with Marx's prescriptive explanation for how political epochs will end, the ID theorist follows along in theoretical footsteps that it might not want to follow: failure.

Koperski, however, is too smart for this, and he knows the Marx analogy isn't supposed to be convincing. He introduces the analogy to make a point about relevance, but the problem is that the point about relevance could be made without the bad analogy. Without the analogy, however, the force of relevance would more easily be seen working on the side of the ID critic rather than on the side of the ID proponent. Also, creating an analogy with a less dominant and traditionally liberal ideology lends some support to a conservative religious position that supports ID. Given that most ID proponents are theists and happen to be conservatives, this makes the intuitive, rhetorical force of Koperski's objection stronger for those who support both kinds of political agenda, but it doesn't make the analogy work.

Validity equivocation:  After presenting the Marx analogy and ending with the rhetorical question, Koperski answers it with the following: “As every logic student knows, the answer is “No.” One's motivations for presenting an argument have no bearing whatsoever on the validity (my emphasis) of the argument. Evaluating a conclusion by questioning one's motivation is an ad hominem attack. Arguments must be judged on their merits regardless of the source” (436).

This quote gives us three things to consider. Let's first clear up the validity issue. It isn't clear what Koperski means by validity. If he means the formal definition of deductive validity, then he is 100% correct. Arguments that are formally or deductively valid can't be made invalid by the identity of the person who presents the argument: this is the genetic fallacy version of the more general ad hominem family of fallacies. Modus Ponens, that paradigm of good reasoning: “If P, then Q. P. Therefore, Q” is deductively valid even if Hitler utters an instance of that argument form.

There are additional points to make about Koperski's seemingly trivially true claim about the validity of arguments. First, Koperski is conflating the formal definition of validity with the informal use of the word valid, which just means true. Second, we might ask: what valid ID arguments are being claimed invalid because of who has presented them? ID arguments and claims, as well as Darwinian/evolutionary arguments and claims about the origins of species and other biologically related issues, are traditionally presented as inferences to the best explanations: these arguments are inductive inferences and are not intended to be valid. So validity of the formal, deductive kind is irrelevant in evaluating these inductive arguments, making Koperski's objection otiose. ID theorists, like Behe, believe the “best explanation” of human origin has to be an intelligent designer because of some kind of “irreducible complexity,” and those Darwinists, like Michael Ruse and Richard Dawkins, believe natural selection can do all the explanatory work necessary to explain the origin of organs like the eye and other complex bits of biological workings without a designer. Their “best explanation” is evolution by natural selection. The Russian Orthodox Christian geneticist and evolutionary biologist Theodosius Dobzhansky expressed it best when he wrote, “Nothing makes sense in biology except in the light of evolution” (1964, 449). ² Evolution is the best explanation—no validity required.

What we have here are not deductively valid arguments that are being evaluated as invalid by means of some ad hominem attack. We have competing inductive, explanatory arguments. So Koperski's charge that an ad hominem fallacy has been committed misses the mark because validity in the deductive, formal sense is not an issue. But what Koperski writes next is of utmost importance: “Evaluating a conclusion by questioning one's motivations is an ad hominem attack” (436). This bears repeating because it is true. But the issue isn't whether the questioning of motivations is an ad hominem attack but whether the questioning of motives (or “attack” if you prefer Koperski's term) is a justified evaluation (attack). The answer to this question makes all the difference.

Ad hominems: justified and unjustified.  Koperski has been too brief in his treatment of the logic and inductive arguments up to this point, but he is right about the attacks or evaluations being ad hominem. I grant there are good reasons to think some of the attacks on ID are both ad hominem and fallacious—like when Richard Fortey calls ID theorists “IDiots” (Fortey 2007)—but one has to understand that not all ad hominem attacks are fallacious. To see this, we first have to understand what kind of mistake is made when a person commits an ad hominem fallacy. Typically, it is difficult to classify mistakes in reasoning because people are particularly creative in how they make such mistakes. In this case, however, the ad hominem argument is fallacious when the evaluation or attack is not relevant to the evaluation of the claims or argument being evaluated. When this occurs, we have a classic relevance fallacy. The objection isn't relevant to the person's argument or claim.

Ad hominem literally means “against the man,” and a classic example of irrelevance come in the case of the title of comedian Al Franken's (now Senator Franken's) book Rush Limbaugh Is a Big Fat Idiot. Attacking Limbaugh for being fat is irrelevant to evaluating the truth of what Limbaugh has said or written. Even being an idiot is irrelevant to what Limbaugh claims because we are to initially judge the claims independently of who utters or writes them. Who presents the claims is irrelevant to whether or not the claims are true, when the claims are factual. Normative claims are far more problematic in this regard, and because we are dealing with explanatory claims that are supposed to be the best explanation, there is a normative element. With this normative element, there is a greater chance of bias on the part of the author's claims, and this is where people tend to run into trouble both presenting and evaluating arguments.

There are clear examples of when attacking the person is a legitimate way to evaluate or object to what the person says. Here are three examples, and I’ll contrast them to Koperski's Marxist professor analogy to highlight the point. In Understanding Arguments, Fogelin and Sinnott‐Armstrong (2009) define three kinds of ad hominem arguments: deniers, silencers, and dismissers (356). Here is how they define each type of ad hominem: “Deniers conclude that a claim is untrue or that an argument is unsound or weak. Silencers conclude that someone lacks the right to speak in a certain context. Dismissers conclude that someone is untrustworthy or unreliable. Each can be either justified or unjustified” (356). What is interesting in these cases is there are justified ad hominem arguments and unjustified fallacies of each variety. I offer some examples to bring each type into focus. I will show that what ID critics are doing in evaluating ID proponents is not fallacious but is justified in many cases as ad hominem arguments against ID theorists.

Case 1: Paid Testimony.  When on trial, we find there are two witnesses, both of whom are getting something in return for their testimony. Witness One is getting money and Witness Two is getting a reduced sentence for prior convictions. The first witness testifies on behalf of the defendant and is a professional crime scene interpreter. The second witness is a jailhouse snitch and is getting a reduced sentence for the testimony. In both situations we have to determine if the witness is reliable and credible. If the witnesses turn out not to be credible because of the incentives they have been offered, they are in effect “testimony for hire.” Then it is completely relevant for the prosecution to question the credibility of the hired professional testifier. And it is equally legitimate for the defendant's attorney to question the credibility of the jailhouse snitch. There are relevant manners of criticisms of these witnesses’ testimonies. So to question these witnesses and to suggest that their testimony is false is not an instance of a fallacious ad hominem attack but is instead a legitimate ad hominem argument against what they claimed to judge, hear, and see.

These kinds of case examples are called “denier”ad hominem because the evaluation or attack claims to deny the truth of what the witness says. Cases of unjustified deniers would be to attack the witness on the basis of something not relevant to the case: being unkempt, fat, short, or from a state university would all be examples of unjustified attacks. These kinds of evaluations of the person are not relevant to the credibility of the information that is presented, but there are relevant examples of objection, and that's the point. For example, not being board certified in a particular medical field could be an instance of a relevant criticism to the claims of a witness, and not having a degree from an accredited university, or making judgments outside of one's field of expertise and competence, could be relevant as well.

Case 2: The Know‐It‐All or Busybody.  We can imagine cases where someone might make a claim that could be true, but the nature of their relationship to the situation is such that they lack the right to speak in the situation. Cases where strangers tell people how to raise their children or how to care for their pets may be correct in their assertions about child rearing and pet care, but to deny them the right to say it in the context can be a justified ad hominem argument. A more striking example would be a case where someone speaks out at an official function, but they lack the official right to speak—a person who doesn't own shares of a stock at a shareholders meeting, for example. A citizen arguing policy in a venue only meant for elected officials or a nurse making a medical diagnosis that should only be made by a doctor are all cases where the person involved could legitimately be silenced even if what they are claiming is true. To silence them is relevant because they lack the right to speak in the context. To deny those who do have the right to speak in the context would be an ad hominem fallacious attack.

Case 3: Salespeople.  This is the subtlest case of ad hominem, and it is what I think most ID critics are engaged in when they evaluate ID proponents. Let's look at some examples. Whether you are buying a car, stocks, or a new dress, a salesperson working on commission is interested in doing one thing and one thing only: making the sale. So it is relevant to question the advice of a salesperson working on commission when she tells you the dress looks great or the car is perfect for you. Or we might make a clearer, albeit fictitious, example between two groups arguing about a political issue with a normative component. Imagine there is a debate about whether we should grant most favored nation status to China. ³ Now, imagine Cisco Systems argues in favor of granting the status, whereas Amnesty International argues against granting most favored nation status. Attacking Cisco's position because of their profit motive would be a justified ad hominem argument. But if we attacked Amnesty International, it would be an ad hominem fallacy. There is nothing about Amnesty International that would justify dismissing their objections to granting most favored nation status to China just because they are Amnesty International and they don't have a profit motive. Their motive is for someone else's gain, the victims of human rights violations, not Amnesty International's gain, and that is the relevant difference in this case.

What are the attacks/evaluations on ID?  Now we can ask the question: Are ID proponents more like Koperski's Marxist professor or more like the paid testifier, know‐it‐all busybody, or salesperson? And because Koperski doesn't cite any actual examples of ad hominem attacks, but only implies that this is what is going on when opponents object to ID, we might see if we can tease apart how the objections might work in a manner that is a justified ad hominem argument rather than as a fallacious ad hominem attack.

One thing we need to look at is motive. And there is an important motive many Christians, particularly fundamentalist Christians, have: they believe they need to spread the word of God. Evidence for this comes from the final verses of Matthew: “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, and teaching them to obey everything that I have commanded you. And remember, I am with you always, to the end of the age” (Matthew 28: 19–20 NRSV).

This biblical verse is known as the great commission, and if I might be allowed to equivocate on the word “commission,” one has to be worried about those working on this commission in the same way that we have to be worried about the salesperson working on commission. In this case, the Christian believes that it is a commandment from God that they do this work, which is more important than any other work that they might do on this earth. So if we are to take this kind of person seriously because he takes this religious charge seriously, then it is legitimate to be concerned in these cases. And a relevant objection to ID on the basis of commission would be a justified ad hominem attack and not the fallacious variety.

What ID theorists need to do is find independent arguments for their ID positions, but they cannot. Just like methodological naturalism is a tenet of science, supernaturalism is a necessary component of ID: there must be a designer, which leads to a second kind of objection that looks a lot like the silencer style ad hominem objection. The problem with trying to argue that ID theorists are justifiably silenced in this way is that we run the risk of slipping into Koperski's second “bad way” of evaluating ID theory, which Koperski argues can't be done. As much as I believe supernaturalism silencing could be a legitimate objection to ID theory, the better objection is to claim ID theorists have an additional commission motive that makes arguments against ID theory justified ad hominem arguments and not unjustified ad hominem attacks.

Conclusion: the question of relevance and a third “good way.”  The issue of attacking or evaluating ID proponents in a manner that questions their credibility is justified when the truth of what ID theorists are asserting could be influenced by their beliefs and motives. Therefore, it is right to question what ID theorists are claiming. If the objection is an evaluation of the relevance of what they are claiming, then there is every reason to attack the credibility of the person arguing—and thus we have a justified ad hominem argument against the person and his argument. If the objection were not relevant, then one would have committed the ad hominem fallacy; it would be an unjustified attack. The real question is one of relevance, and it is clear from many cases, especially when the person is trying to obey the great commission, that this kind of ad hominem evaluation of ID theorists is both relevant and good and not an instance of the attacking ad hominem fallacy.

Koperski's 2008 paper presented us with four ways to evaluate ID theory, two of which were supposed to be good and two were supposed to be bad. Unfortunately, one of the bad ways is so similar to an unstated good way that the good way was left out. It's this third good way that needs to be understood, for it is one of the main sources of confusion and debate between ID theorists and their critics. Understanding this confusion between justified ad hominem arguments and unjustified ad hominem attacks (fallacy) will help prevent legitimate evaluations of ID theorists from devolving into unjustified attacks. We have a third “good way.”