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(intro music) Hello. I'm Paul Henne, and I'm a philosophy graduate student at Duke University. And in this video, I'm gonna talk to you about an informal fallacy called "ad hominem." The phrase "ad hominem" might sound a bit bombastic, but I assure you that it's an interesting and useful critical thinking tool. The latin phrase roughly means "to the person," and that's exactly what this fallacy is. It's an attack against the person making the argument, rather than an attack against the argument itself. But let's see if we can pin down exactly what this means by using an example. Suppose that my friend Vlad made the following argument. "Cats stay indoors and use a litter box, "while dogs need to be walked "and they have to run outside. "Dogs are just more work. "Therefore, cats are better domestic pets than dogs." And then I reply, "Yeah, Vlad, but you're a total jerk." So I disregard Vlad's argument in favor of cats and decide to get a dog. So let's think about my reply to Vlad's argument. Maybe you think that my reply is a completely good response to Vlad. Suppose it's true that Vlad is a total jerk and that I think no one should respect him or listen to what he says. I think Vlad has bad character in some way. Therefore, his argument should be rejected. So my response is good, right? If this example doesn't convince you, suppose that Vlad is really Hitler. Hitler is a total jerk, so his conclusion is false, or his argument isn't valid. Does that sound good? But let's represent my argument more generally, to see why this reasoning is actually flawed. Premise (1): Person P makes claim C, "cats rule, dogs drool." Premise (2): Person P has unsatisfactory standing or circumstance ("Vlad is a total jerk.") Conclusion: Therefore, claim C is false. (it's false that cats are better domestic pets.) While it might seem appealing in some cases to say that this is a good argument form, it would be generally wrong to think so. The standing of the person making the argument in most cases will be irrelevant to the validity or the soundness of the argument. And this is the misconception that I would like to correct in this video. Simply because Vlad is a total jerk doesn't mean that his claim about cats as better domestic pets is false. He could be a complete jerk, yet still make a good argument in favor of cats as domestic pets. So let's look more closely at this fallacy and at its four sub-types. The first type of ad hominem fallacy is the abusive type. To understand this type, let's return to our first example where I called Vlad a jerk. In this case, I've committed the abusive ad hominem fallacy. In other words, I've attacked or abused the person making the argument. I haven't criticized the argument itself. More specifically, I've abused Vlad by simply attacking his character, and then I equated his poor character with his argument. This is a fallacy because, while the speaker, Vlad, might not have good standing as I see him, his argument may still be valid, that is, cats might be better domestic pets. Another type of Ad Hominem fallacy is the circumstantial type. Let's suppose that, when I'm talking to my friend Catherine, she makes the following argument. Premise (1): Animals are sentient beings. Premise (2): If a being is sentient, then killing it for food is immoral. Conclusion: Therefore, killing animals for food is immoral. Suppose then that I make the following statement in reply: "Yeah, but Catherine, you work for a vegan food company. "So your argument must be invalid." In this case, I attack Catherine's circumstance, that she works for a vegan food company, instead of her argument. Maybe I thought that she may have a conflict of interest in making her argument, that is, she wants to sell more vegan food products. So she may be motivated to give a faulty argument in favor of veganism. Despite this potential conflict of interest, my reply to her argument does not effectively criticize her argument. Although she works for a vegan food company and may have a conflict of interest, she may also have a perfectly valid and sound argument supporting her conclusion that killing animals for food is immoral. If I wanted to effectively combat her argument, I could maybe argue that animals aren't sentient, or attack some other premise in her argument. The third type of ad hominem fallacy is called "tu quoque," which roughly means "you also." To explore this variation of the fallacy, let's return to our previous example. But suppose that my reply to Catherine's argument were "Yeah, Catherine, but you eat meat. "So you support the killing of animals for food. "Your argument must be invalid." In this case, I highlight Catherine's standing, in that she doesn't act in a way that's consistent with her conclusion. I take her hypocrisy to invalidate her argument, or at least to be a reason to reject her conclusion. But again, my reply doesn't effectively critique Catherine's argument. I've not even mentioned any problems with the premises or the conclusion at hand. So despite her purported hypocrisy, Catherine might have an effective argument and just think that it's immoral that she eats meat. The last type of ad hominem fallacy is the guilt by assocation type. Let's suppose now that my response to Catherine's argument is this: "Yeah, Catherine, but towards the end of his life, "Hitler was a vegetarian. "So, you might have made a similar argument. "Since we'd reject his argument simply because he's Hitler, "the most evil person in the world, "we should obviously reject your argument, too." What have I done in this case? Well, I've associated Catherine with a person of very poor character, and then I've suggested that it is a reason to reject Catherine's argument. This, however, is fallacious, because while Hitler was a terrible person who committed some of the most atrocious acts in history, he still may have made a valid and sound argument about the morality of eating animals. Moreover, Catherine's slight association with Hitler does not invalidate her argument. And by discussing her character, I have not even addressed the issue at hand, veganism. Let's look at the fallacy in our general schema. The arguments that I've been making against Catherine are of the following form. Premise (1): Catherine claimed that killing animals for food is immoral. Premise (2): But she has poor standing or circumstances. Conclusion: Therefore, it is not the case that killing animals for food is immoral. Have I committed an informal fallacy in these cases? Yes! I have not invalidated or even addressed the subject of Catherine's argument. Rather, I have personally attacked her standing and character. This is the ad hominem fallacy, and you will see it often. It is important to note, also, that philosophers have many questions and concerns about this fallacy and when a person's standing and character are relevant to an argument. But we will have to save these questions for another video. Subtitles by the community