Plausibility and Same-Sex Marriage
In philosophical discussions, we bring up the notion of plausibility a lot. “That’s implausible” is a common form of objection, while the converse “That’s plausible” is a common way of offering a sort of cautious sympathy with an argument or claim. But what exactly do we mean when we claim something is plausible or implausible, and what implications do such claims have? This question was, for me, most recently prompted by a recent pair of blog posts by Justin Weinberg over at Daily Nous on same-sex marriage. In the posts and discussion, Weinberg appears sympathetic to an interesting pedagogical principle: instructors may legitimately exclude, discount or dismiss from discussion positions they take to be implausible.* Further, opposition same-sex marriage is taken to be such an implausible position and thus excludable/discountable/dismissable from classroom debate. Is this a legitimate line of thought? I’m inclined against it, and will try to explain why in this post.**
What is plausibility?
Right off the bat, we should try to get clearer on the concept of plausibility. Unfortunately, there doesn’t seem to be a rich literature on this (Though I encourage commenters to enlighten me here!). Plausibility is admittedly a well-explored issue in epistemology, especially since a 1981 article by Dennis Packard, but the literature there seems to presuppose without discussion a background understanding of what plausibility is, and concerns itself with formal ranking models. More usefully, Nicholas Rescher (2005) has offered 3 different (plausible?) conditions for a claim’s being plausible: (1) When a preponderance of evidence favors it; (2) when it holds in more possible worlds than its negation; and (3) when credence in it passes some probability threshold, like 1/10. I don’t like definitions (1) and (2) as the notion of plausibility collapses into roughly what one is justified in believing, which is too narrow. (3) is more appealing, as it straightforwardly allows one to say one (weakly) believes X is correct but that ~X is plausible – which I take it is sometimes how the notion is deployed.
The probabilistic notion has its own issues. How, for instance, are we supposed to convert our moral beliefs into proper credences? I myself am baffled when asked to assign such numbers, at least to non-empirical questions of morality. Maybe we can fudge it – there’s some level of confidence, intuitive to most of us, above which we would rate some claim as ‘plausible’. But then we have to ask, how could such a fudgy notion have the sort of pedagogical and dialectical role it is meant to have? In particular, why should falling below that threshold rule some topic out from discussion and debate?
The role of implausibility
One route is argument by analogy. Weinberg brings up slavery in this context – we’re so confident slavery is wrong, there’s no need to take pro-slavery arguments seriously in the classroom or during debates. Weinberg and others are similarly so confident that same-sex marriage is OK that it should be similarly excludable. I worry this is too exclusionary, though. As philosophers, we often take strong positions on issues; for instance, many deontologists are absolutely convinced that utilitarianism is incorrect due to its narrow value focus, ignorance of central moral issues and absurd implications. But it would be inappropriate for them to exclude utilitarianism from classroom discussion on these grounds, and decline to engage in debate with utilitarians on the grounds that they’re just silly.
Perhaps we could differentiate things like utilitarianism’s alleged implausibility from slavery’s (and same-sex marriage’s) by adverting to the latter’s association with bigotry and disrespect (though Weinberg specifically rejects this strategy in comments). Slavery was historically often justified on racist grounds, and some argue same-sex marriage is opposed on homophobic grounds. So the principle would be something like: X is excludable if it is (a) implausible and (b) expresses a bigoted/disrespectful position. Or maybe (b) could be fleshed out in terms of human rights? The idea would be that some ideas are both so unlikely to be true AND harmful that discourse over them is inappropriate.
I would say such an exclusionary principle is plausible (see what I did there?) but still misguided. In fact, instructors should be engaging with arguments for even ‘beyond the pale’ institutions like slavery, as well as ‘obviously’ immoral activities like lying and murdering. Understanding why some position is (deeply) misguided can be illuminating, causing – as Mill notes – one’s own considered views to become stronger and more clear in contrast. For example, Hare’s famous Juba and Camaica thought experiments show that utilitarians have to address whether slavery is intrinsically wrong, if so why, and if not how to reconcile that implication with strong contrary intuitions. Even if they ultimately agree we shouldn’t enslave people, their moral theory becomes more clear and well-worked out when pressed to explain why.
An alternative analogy wouldn’t be to slavery, but empirically certain yet politically controversial matters like climate change, or uncontroversial issues like the falsity of phlogiston theory. A class on climate change may legitimately dismiss climate denialism based on the massive amount of evidence, and a class on chemistry may legitimately dismiss phlogiston theory – because of the implausibility of climate denialism and phlogiston theory.
In the case of climate change, I’m not so certain we should dismiss denialism. Again, given that evidence is supposed to be so decisive against denialism anyway, exploring that evidence would only provide students with a proper understanding of the issues. That understanding is important for engagement in further debates, and better than mere reliance on expert opinions. Indeed, by having students engage with denialists, one can help them become the sorts of experts that can refute denialism.
On phlogiston theory, by contrast, I’d agree it’s not worth discussing outside a history/sociology of science course. But this because there’s no current controversy over phlogiston theory, almost no one takes it seriously, and it is mostly irrelevant.
Application to Same-Sex Marriage Debates
Just as we should be inclusive about discussion of ‘settled’ issues like slavery and climate change, we should be inclusive when discussing and teaching about same-sex marriage. By engaging with opponents, those who support marriage equality can flesh out what they take marriage to be (an issue recently emphasized by Spencer Case, in response to Weinberg), what is at stake in the political debate and where, exactly, they disagree with interlocutors. Dialectically, this allows for more rigorous and convincing argumentation. Pedagogically, this allows people to properly grasp what is going on in the broad debate, learn about the commitments that go along with various positions and come to their own opinions based on reasoned consideration rather than group-think or rhetoric. If proponents of same-sex marriage are right and opposition is indeed implausible, they should be confident that many benighted opponents will come around when faced with rigorous discussion (as, I believe, has been the case).
To be sure, there may be *other* grounds to exclude a topic like same-sex marriage from discussion. It’s not relevant to every class and discussion. And perhaps, if it is a non-issue in society, one could exclude it due to more general irrelevance or obscurity (Weinberg sometimes adverts to this sort of reasoning as well). Student interest, general relevance and practical import are, to my mind, perfectly good grounds for designing a syllabus. And even steering debates away from obscure issues that others in a classroom just don’t care about may be fine. But given that same-sex marriage is such a relevant topic politically at the moment – with the US Supreme Court set to make a landmark decision on the issue in the next year and many nations’ policies in flux – we are not likely at the stage where exclusion of the topic is legitimate on irrelevance or obscurity grounds.
But of course, all this applies to the meta-issue of whether and how same-sex marriage should be discussed – that is, we should have a healthy debate over whether or not Weinberg is right. And even by Weinberg’s lights, this is the case – he doesn’t seem to think that support for a decision to engage with same-sex marriage opponents is implausible. Which, in turn, means Weinberg should at least be on board with a classroom discussion and debate (when relevant) over this very issue: should proponents of same-sex marriage seriously engage, in the classroom and beyond, with opponents whose views they find implausible? Though I would answer ‘yes’, I also think this is itself an interesting and worthy topic for discussion and debate.
*At least, I take this to be Weinberg’s position – it’s not explicitly stated, and this is what I infer from his comments. Also, notably Weinberg is fine with talking about same-sex marriage opponents’ positions more broadly – but more to explore why they’re so deeply mistaken, rather than inquire as to whether or not they’re correct. It’s the latter sort of open-minded inquiry into veracity that I am interested in here.
** I argue that Weinberg is mistaken to exclude debate over same-sex marriage even if same-sex marriage opposition turns out to be implausible; strictly speaking, I’ll here be neutral on whether such opposition is in fact implausible.