In the final comment on my most recent CT post, John Q strategically grants a premise from an earlier comment by poster Matt: John Q grants that “it’s perfectly plausible that the number of US golfers exceeds the population of Australia.” This was not a concession to Matt’s main point, as John Q goes on to point out that it’s “highly unlikely that this fact contributes much in way of meeting people from very different social networks.”

Rather than bringing us back into the substance of this disagreement, I want to go off about something entirely different. As you’ll soon see, I’m far out of my depths on this one.

Call the claim as formulated by John Q, that “it’s perfectly plausible that the number of US golfers exceeds the population of Australia,” “PERFECTLY PLAUSIBLE.”

PERFECTLY PLAUSIBLE is under my skin. Let me try to explain why.

First, PERFERCLY PLAUSIBLE may be true. That would be interesting, just on the substance.

Second, PERFECTLY PLAUSIBLE could be true even if the thing it claims to be plausible is false, and it could be false even if the thing it claims to be plausible is true. That is, PERFECTLY PLAUSIBLE can be true (false) even if it’s false (true) that the number of US golfers exceeds the population of Australia. That’s because PERFECTLY PLAUSIBLE is (I think) a claim about what it would be epistemically reasonable to believe if you had some information on which to infer the relative quantities of US golfers and Australians,[1] but not enough information for deducing the fact being claimed to be perfectly plausible.

Third, and weirdly: In the context of the post, the truth (or otherwise) of PERFECTLY PLAUSIBLE strikes me as more interesting than the truth (or otherwise) of the claim being forwarded as perfectly plausible, that is, that the number of US golfers exceeds the number of Australians. When I read John Q writing that it’s perfectly plausible that the number of US golfers exceeds the number of Australians, I thought, “wow, that’s fascinating,” and I couldn’t stop thinking about it. If John Q had instead just checked and affirmed Matt’s supposition, writing that the number of US golfers does indeed exceed the number of Australians, I’d have thought “that’s wild, Americans and their golf, amIright?” It’s the plausibility of the claim, and not its (plausible) truth, that fascinates me. This isn’t exactly paradoxical: PERFECTLY PLAUSIBLE forwards a different claim than the claim it asserts to be plausible, so it’s no great shock that in some contexts it could be more interesting. You might be surprised to be more interested in PERFECTLY PLAUSIBLE if you thought it was just a vaguer version of the claim that US golfers exceed Australians. But it’s not that. It tells us something (so far imprecise) about what inferences it would be reasonable to draw on the basis of a (so far imprecise) body of knowledge. It tells us that we shouldn’t be surprised to hear someone who knows their stuff but hasn’t looked up the details telling us that the number of US golfers exceeds the number of Australians.[2]

Philosophers use the language of “perfectly plausible” all the time, and it’s generally used to lubricate a certain kind of argumentative move. It indicates that there’s some variable that we could inquire into, but that the argument being advanced (probably despite appearances) doesn’t ultimately stand or fall on the outcome of that inquiry. So, if I’m defending a moral principle of equal opportunity, I might say “but it’s perfectly plausible that free will is an illusion, so we should consider what this principle would tell us if that perfectly plausible thing were indeed true and ask whether the thing it would tell us on that condition is a palatable thing for such a principle to tell us.” (I would say that because some people seem to think, wrongly, that equal opportunity only makes sense if free will is real.) This is what John Q is doing in PERFECTLY PLAUSIBLE. He’s saying to Matt, “you may well be right about the relative numbers of Australians and US golfers. My point stands either way.” It doesn’t matter to John Q’s argument whether the number of Australians exceeds US golfers; what matters is that it plausibly could be true, and it wouldn’t matter if it were.

I think what I’m hung up on here is this: I think the most typical uses of “perfectly plausible” in philosophy apply it to claims whose truth status is difficult to discern or difficult to make a part of the common ground for the argument, e.g. normative claims or claims about free will. The thing John Q asserts as plausible is a descriptive fact, and one we could relatively easily learn the truth status of. Yet even in these circumstances, I think, PERFECTLY PLAUSIBLE is a more interesting claim than “Australians < US golfers.” Contrast this case with the illusion of free will. If I knew free will was an illusion (and if that fact could easily be brought into common ground), there would be no point in asserting the fact as plausible. I’d say instead, “we know free will is an illusion, so let’s see if the implications of my principle, given that that’s so, are acceptable.” What is the difference between this case and PERFECTLY PLAUSIBLE? Supposing Australians < US golfers, what is it that John Q conveys, intentionally or not, by writing PERFECTLY PLAUSIBLE over “Australians < US golfers”? Or, why do I care more about whether this comparison is plausible than whether it’s true?

Maybe we could translate PERFECTLY PLAUSIBLE into a claim with no epistemic language, such as “the two quantities in question are in the same ballpark.” But I don’t really think that would preserve the meaning of PERFECTLY PLAUSIBLE. One reason I have for doubting it is that the whole time this has been under my skin, I haven’t figured out how to (dis)confirm PERFECTLY PLAUSIBLE. In contrast, I could quite easily learn the two quantities and see if I think they’re in the same ballpark. And, if the two numbers are in the same ballpark, then “the two quantities in question are in the same ballpark” is true (and its denial false), even if anyone who knows their stuff should have been surprised to learn that fact. But, as I said, the truth of Perfectly Plausible just doesn’t turn on whether the number of golfers in the US exceeds or is in the same ballpark as the number of Australians.

On the one hand, I know just what John Q was doing with this construction. On the other hand, I can’t make precise to my own satisfaction what PERFECTLY PLAUSIBLE means in this context, and why I should find PERFECTLY PLAUSIBLE (and its truth status) so much more interesting than the claim that PERFECTLY PLAUSIBLE asserts to be plausible. Is there something simple that I’m missing? In what other kinds of cases might we be more interested in a claim’s plausibility than its truth? Is it about when we have reason to be concerned about what people might be in a position reasonably to infer, true or not?

Suppose the US is embarrassed to find that it is plausible that US golfers exceed Australians. Should they look into the numbers and then be reassured if they learn that it’s plausible yet false? Or should they be alarmed by, and take action against, the mere fact that it’s plausible? (Only half joking here.)

[1] I know that “the number of Australians” must be different than the “population of Australia” but I think I’ll write this more clearly if I use them interchangeably, and the difference won’t matter to the question I have.

[2] Does it also tell us that we should be surprised to hear someone who knows their stuff but hasn’t looked up the details contradicting the claim? I’m not sure, but I doubt it.