The Rules of Thought: Fregean mental content

I posted a couple of days ago about one of the three main hooks into The Rules of Thought -- an explanation and theory of the a priori. Today I'll write about another -- a theory of mental content. Again, I'm just being completely shameless here and talking about why you might be interested in our book. Please skip if you find that sort of thing distasteful.

In our book, Ben Jarvis and I defend a Fregean theory of mental content. We hope that it does three things: it provides the best resolution to (the most interesting version of) Frege's puzzle; it has a plausible story to tell about the relationship between Fregean senses and the psychological states that constitute propositional attitudes; and it is able to underwrite the epistemology of the a priori. We came to our work on mental content via the epistemology, but we consider this latter project independently motivated and foundational. Our treatment of mental content comprises Part I of the book, and we hope that the book is as much a contribution to mental content as it is to epistemology.

Consider these two propositions:

1. Some roses are red.
2. Some roses have a colour.

Here's a very natural idea: it's part of the essence of these two propositions that (1) entail (2). There are lots of ways one might fill this out, but it's very natural to say that part of what makes proposition (1) the proposition that it is is that any time it is true, (2) is also true. We take this natural idea and carry it a step further. Not only do propositions have truth conditions necessarily and essentially; they also have rational acceptance conditions necessarily and essentially. Part of what makes (1) and (2) the propositions that they are is that they stand in a particular rational relationship to one another. In particular, (1) rationally entails (2), in addition to metaphysically entailing it.

We call these rational entailment relations Fregean senses. You can think of Fregean senses in our sense as a kind of truth conditions. If you're comfortable thinking this way, they're equivalent to sets of 'rationally possible worlds' (where there are some of the latter in which, e.g., Hesperus is not Phosphorus). Fregean senses encode what a content rationally commits one to.

Our unstructured Fregean senses constitute a departure from Fregean orthodoxy, which would have structured senses. This is motivated in significant part by the kinds of considerations I discussed in this post last week. We think there is an important theoretical role to be played by such unstructured entities, because the notion of rational commitment is fundamental to our story about mental content. (Of course, we also believe in more structured counterparts -- these, we call 'propositions'. Naturally, there are many ways to apply labels in this neighborhood; we try to justify our terminological choices, but the possibility for superficial disagreement here is significant.)

You need Fregean senses, we think, for basically the same reason Frege thought: to account for Frege cases. On our view, however, the most fundamental category of Frege cases isn't about the possibility of informativeness, or the explanation for certain kinds of behaviour. Frege's puzzle is ultimately a puzzle about rationality. If I believe that Hesperus is a star, and then I learn that Hesperus is a planet, I face rational pressure to revise my previous belief. This wouldn't be so if I learned instead that Phosphorus is a planet. None of the neo-Russelian views out there, we argue, can explain this fact. We explain it very straightforwardly: HESPERUS and PHOSPHORUS are different contents, which carry different rational relations.

(This is a view about the metaphysics of attitudes, not about the semantics of attitude reports. As we explain in the book, our view in consistent with a lot of views -- including neo-Russellian ones -- about the latter.)

Rational commitments, on our story, are primitive and fundamental. Chapter 5 of our book draws an analogy between our way of thinking about senses with Timothy Williamson's suggestion to put knowledge 'first'. We think it is a mistake to seek substantive explanations for why certain rational entailments obtain between certain contents. This move might motivate some to suspect us of shrugging off the most fundamental questions, but this isn't necessarily the case. True enough, calling senses fundamental is in some sense a way of moving the bump in the carpet somewhere else. But we have a lot to say about its new location: the psychological realisation of Fregean sense.

If you spot us the suggestion that there are some abstract entities called 'propositions' that have inherent and essential rational relations with one another, a major open question becomes: how is it that we humans manage to stand in any kind of significant relations to these obscure entities? This is among the most central questions in Part I of our book. A nice and convenient answer, were it true, would be the familiar conceptual role theorist's answer: contents can be characterised by particular inferential roles, and a subject thinks thoughts with those contents by virtue of dispositions to infer according to those special roles. (This should remind you of Christopher Peacocke.) Unfortunately, as people like Quine and Williamson have shown, this nice and convenient answer isn't true. We need a more complicated story.

Ben and I agree with Peacocke that there are certain privileged inferential roles that play a special, content-fixing role. The inference from "is red" to "is coloured" is special in a way that that from "is red" to "looks at least a bit like sriracha" is not. But we don't think that this special inference need be encoded at all directly in the dispositions of any subject who possesses the concept RED. Instead, we suggest that these special inferences have a privileged teleo-normative, rather than dispositional, status. Part of what it is to possess the concept RED is to be such that inference to COLOURED is proper or correct. Part of what makes a football player a goalie is that she is supposed to prevent the ball from going into the net; it is partly in virtue of her behaviour that she is subject to this norm. But it's not a requirement that she be very good at her job.

In a closely analogous way, we think that there are rules of thought. Part of what it is to think is to be subject to certain rational norms; for example, the norm that one should infer (2) from (1). Subjects constitute thinkers partly in virtue of their behaviour and dispositions, but in a way that doesn't guarantee a particularly high level of compliance. According to the story of the book, subscription to particular rules emerges in virtue of the best systematisation of the myriad first-order dispositions to apply concepts in various ways. I can't go into much more detail in this blog post, but a different kind of analogy might help get the approach into mind. Imagine a wooded area, with various significant locations along the perimeter. People need to get from place to place, via the woods, and at first, it's pretty arbitrary what route they take. They don't all just go in a straight line, because some parts of the woods are easier to walk through than others. Over time, paths emerge. Lots of factors influence with paths come to exist -- which destinations are most important, the natural lay of the land, which routes already exist, etc. But once there are paths, there are, in some sense, correct ways to get through the woods. This path is the way you're supposed to go. This, even though nobody ever laid down the law; the path emerged over time as the product of lots of other more arbitrary activity. There's lots more to say about how this could work -- and there are many respects in which the analogy is imperfect -- but I hope that this gives at least a rough idea of the teleo-normative inferential roles that we discuss in the book.

(It is worth noting that an implication of the approach is that we need not construe contents individualistically. We're entirely open to the idea that contents are public, and the best systematisation of first-order dispositions occurs at a broader social level. If this is right, our view implies that rationality, like meaning, ain't in the head. That's fine with us.)

I'll write one more post about the third hook into the book -- consideration of the role of intuitions in epistemology -- soon.

The Rules of Thought: Philosophy and the a priori

I'm going to live up to the blogger stereotype and set a few posts on autofocus. The shameless project is to make the case that you might have good reason to read The Rules of Thought, the book that Benjamin Jarvis and I recently wrote. (OUP catalogue page) (my webpage)

I think that there are three possible hooks into our project. One of them -- the one that represented our own way into the project -- concerns the epistemology of the a priori in general, and the epistemology of philosophy in particular. Ben and I trace this interest pretty specifically to 2005, when, while PhD students at Brown, we took Joshua Schechter's seminar on the a priori, and also attended Timothy Williamson's Blackwell-Brown lectures, which eventually became The Philosophy of Philosophy. We were attracted by traditional idea that in many paradigmatic instances, philosophical investigation proceeded in some important sense independently from experience, but came to appreciate that (a) there were deep mysteries concerning the explanation for how this could be, and (b) there were strong challenges that suggested that the traditional idea couldn't be right. For example, the traditional idea has it that judgments about thought experiments constitute appreciate of facts that are both a priori and necessary; but Williamson gave what is now a somewhat famous argument that this can't be so: thought experiments don't include enough detail to entail the typical judgments. So the best they can support is something like a contingent, empirical counterfactual: if someone were in such-and-such circumstances, he would have JTB but no K, etc.

We wrote a defensive paper in response to Williamson's argument, explaining how one can understand the content of thought-experiment judgments in a way that renders them more plausibly necessary and a priori, invoking the notion of truth in fiction. ("Thought-Experiment Intuitions and Truth in Fiction" -- (draft) (published)) That paper did two useful things: it gave an objection to Wiliamson's treatment, and it defended a traditional aprioristic picture from Williamson's particular critique. But on the latter score, it was purely defensive; it did little to explain how a priori justification or knowledge was possible, or to articulate just what apriority could consist in. Another paper, "Rational Imagination and Modal Knowledge," (d) (p) gave a bit more epistemological background, and a focus on modal epistemology in particular. By the time of that paper, we were underway on the book.

What we needed, we realized, was a much fuller story about apriority, including detailed engagement with extant critiques of the notion. We give this in Part II of The Rules of Thought. Some of the critiques -- in particular, some of those from Williamson and Hawthorne, as well as some similar challenges from Yablo and Papineau -- show that a characterisation of apriority in terms of more psychological states like knowledge and justified belief is extremely difficult, perhaps impossible. (Here's a related blog post from last year.) Our general characterisation of the a priori is a negative one, given in terms of propositional justification. A subject has a priori propositional justification for p just in case she has justification for p, and this isn't due in constitutive part to any of the subject's experiences. We explain how this approach avoids the challenges to the a priori that are in the literature, and argue that there is strong reason to think that philosophical investigation is often a priori in our sense. The focus on propositional justification requires a fairly strong version of the traditional distinction between warranting and enabling roles for experience, which we attempt to explicate.

The negative characterisation is thin by design. We are explicitly open to a kind of pluralism about apriority, according to which various positive epistemic states can realise apriority. The state we focus on most is what we call 'rational necessity' -- certain contents are, we think, by their nature such that there is always conclusive reason to accept them. (Much more on this idea in another post on another motivation for the project.) But we allow that other states may realise apriority as well; we are open, for example, to the idea that it is a priori that perception is generally reliable, even though this isn't rationally necessary. Perhaps some kind of pragmatic explanation for these a priori propositions may be found.

In the context of our theory of the a priori, and our more detailed positive story about rational necessity, we rehearse the main ideas from our two previous papers on philosophical methodology: thought-experiment judgments, properly understood, often have contents that are rationally necessary, hence a priori; so likewise for many judgments in modal epistemology concerning what is metaphysically possible. This all happens in Part II of the book.

So that's the first hook for our book: understanding the a priori and the epistemology of philosophy. We tell a story that is able to vindicate a number of pretty traditional ideas about how philosophy works (but without problematic focus on words or concepts). The other two hooks will each get another post -- one concerning Fregean ideas about mental content, and one about the role of intuitions.

Motivating a 'Hybrid' Epistemology

I guess I ought to make a point of announcing on my blog that my book with Ben Jarvis has finally been published. (That's UK only at the moment; it'll be worldwide later this month.) Here's OUP's official page. There were some delays with the printing that pushed things back a month or two longer than expected, but on the whole, I'm very pleased with the experience we had with OUP.

One of the central themes in The Rules of Thought is that there is an important sense in which the norms of rationality are objective: they apply universally to all thinkers, regardless of the subjects' rational limitations. We're motivated to say this in significant part because of cases of 'blind irrationality' -- situations where subjects fail with respect to rationality, in a way in which no intuitions or inclinations alert them to their error. There is an important sense in cases like this in which these are genuine failures of rationality; therefore, in this sense, the demands of rationality are not relative to the subject's limitations. The subject is doing the best he can do, given his limitations. This motivates us to the fairly strong view that for 'rational necessities' -- roughly, those truths that someone might want to call 'analytic' or 'conceptual' or maybe 'a priori' -- subjects always have conclusive reason to accept them. That is, everyone always has propositional justification for all of these truths. For example, my grandmother has propositional justification for every arithmetical truth. This is surprising to many, but Ben and I have arguments in the book that I think really do show that this has to be right.

But there is a puzzle that comes from this way of setting things out. It's a puzzle that's brought out really nicely in this new paper by Sharon Berry, "Default Reasonableness and the Mathoids." (Her target isn't views like ours, but the intuitions she's trading with are poignant for us.) We think that complex arthmetic truths -- Fermat's Last Theorem, for instance -- are always propositionally justified in the same way that simple ones -- 1+4=5, for instance -- are. But if this is right, it's not straightforward to make sense of the intuition that simple arithmetical premises are legitimate starting places in proofs in a way that complex arithmetical premises are not. Berry's central thought experiment involves the Mathoids, who find Fermat's Last Theorem (or other complex truths) immediately, primitively compelling in the way that we find simpler truths. She observes that it's intuitive that their proof method is unjustified, but argues that it's hard to find a principled difference between them and us. This seems to me exactly right.

The solution Ben and I have been thinking about -- this is discussed briefly in the book, and at greater length in a paper we're working on -- is that we need a 'hybrid' epistemology. We're still convinced by the arguments mentioned above that there must be an important epistemic element that doesn't depend on any of the contingencies of human psychology. To this extent, we're committed to the falsity of a thoroughgoingly virtue epistemology according to which epitsemic competences are the only fundamental epistemically normative element in town. But the virtue story also has something importantly right: the story we tell about propositional justification can't be the whole story either. The messier, psychology-laden doxastic justification story can't be given entirely in terms of propositional justification. We need to say something more contingent, about how the belief is formed. Virtue epistemology seems promising -- we want to say that there are virtuous traits and vicious traits, with respect to believing what is propositionally justified, and that these make a difference for doxastic justification and knowledge. The challenge, of course, is to describe in what these virtues consist. (If you want to distinguish us from the Mathoids, reliabilism is a clear non-starter.)

We have some tentative ideas for how this might go, but I'll save them for later. The main point of this post is to suggest that there's strong reason to think we might need two independent stories here: one for 'pure' epistemic statuses like propositional justification (the minimalist story that is a main theme in our book) and one for 'impure' epistemic statuses that bring in the psychology (the virtue story we're thinking about now). Neither will do on its own.