Thread by @FeserEdward

1/12 The ignorance of basic logic is breathtaking (and note that here too at least one of these people somehow got a PhD). The answer is: No, when evaluating an *argument*, motives are completely irrelevant. What motives are relevant to is *testimony*. These are often confused.

2/12 Hence, suppose the only evidence that some suspect committed a crime is the testimony of an alleged eyewitness, but you have evidence that that eyewitness has a personal grudge against the suspect. Then you have good reason to doubt the testimony. No fallacy there.

3/12 Or suppose that a guy at the iPhone store tells you that iPhones are the best product on the market. Even if he’s an expert on the subject, you have reason not to take his expert testimony too seriously, because you know he has a motive to sell you a phone. No fallacy there.

4/12 However, if someone gives you an *argument* – that is to say, premises in support of a conclusion – then whether the conclusion follows from the premises (either with deductive validity or probability) has nothing whatsoever to do with the person’s motives.

5/12 An argument that is either valid or at least cogent (i.e. renders the conclusion at least probable) remains so even if the person giving it has bad motives. And an argument that is invalid or non-cogent remains so even if the person giving it has good motives.

6/12 Someone might say “OK, but what about the premises themselves? What if they rest on testimony?” If they do, then it is not necessarily fallacious to doubt that testimony if you have grounds to doubt the person’s objectivity. However,

7/12 typically there will be arguments for the premises too, & *those* arguments will be either valid or invalid, cogent or not cogent, regardless of the motives of the person giving them. Now, in the case of a book like Scruton’s (which occasioned the comments I’m responding to)

8/12 there are going to be lots of arguments, and the author’s motives are completely irrelevant to their validity or cogency. To be sure, there are bound at some points to be premises that are supported by reference to expert testimony, and motives will be relevant there.

9/12 But “relevant” doesn’t entail “decisive.” Hence, if you say “But Scruton cites experts who help his case,” that doesn’t by itself prove anything. Are they truly experts? Does he also discuss experts on the other side? Does he give reasons for favoring the one over the other?

10/12 The answer in each case happens to be “Yes.” So, it’s no good simply to appeal to motives here as if that at last gave license to reject his position, because he has given *arguments* purporting to show that motives have not unduly influenced the outcome of the inquiry.

11/12 And even if there were good reasons to be suspicious of Scruton’s choice of which experts to rely on in this or that case, that wouldn’t magically nullify the validity or cogency of *every* argument he gives.

12/12 The bottom line is that evaluating a work like the Scruton book in question requires doing actual work and serious thinking. It’s not something that can be dismissed w/ a smartass quip & appeal to motives. A random dumbass Twitter jockey wouldn’t know this, but a PhD should