Representational Realism and the Problem of Tacit Belief

Since 2019, I've been working on a new paper on belief, "Dispositionalism, Yay! Representationalism, Boo!" Yesterday, I received page proofs. It will appear in print in 2026 (in a collection I'm co-editing with Jonathan Lewis-Jong: The Nature of Belief, with Oxford). I'll share an excerpt (lightly edited) as this week's post.

Industrial-Strength Representational Realism about Belief

The view I'm critiquing is "industrial-strength representationalism" in the spirit of Jerry Fodor and Eric Mandelbaum. Industrial-strength representationalism is committed to four theses:

Presence. In standard, non-“tacit,” cases, belief that P (where P is some propositional content like "there's beer in the fridge") requires that a representation with the content P is present somewhere in the mind.

Discreteness. In standard cases, a representation P will be either discretely present in or discretely absent from a cognitive system or subsystem. Representationalist models typically leave no room for representations being, say, half-present or 23% present or indeterminately hovering between present and absent. Some marginal cases might violate discreteness -- nature has few truly sharp borders, if one zooms in close enough -- but these will be brief or rare exceptions.

Kinematics. Rational actions arise from the causal interaction of beliefs that P and desires that Q, in virtue of their specific contents P and Q, or at least in virtue of syntactic or architectural correlates of those specific contents (e.g., Fodor 1987). Similarly, rational inferences involve the causal interaction of beliefs that P with other beliefs to generate still more beliefs. This is central to the representational realist’s causal story.

Specificity. Rational action arises from the activation or retrieval of specific sets of beliefs and desires P1…n and Q1…m, as opposed to other, related beliefs and desires P’1…j and Q’1…i. More accurately, rational action arises from the activation or retrieval of the specific representations whose storage, in the right functional location, constitutes possessing the beliefs and desires P1…n and Q1…m. Similarly, rational inference arises from the activation or retrieval of specific sets of representations.

The Problem of Tacit Belief

Back in the late 1970s to early 1990s, that is, in the heyday of philosophical representational realism about belief, several representationalists noticed what I'll call the Problem of Tacit Belief (Field 1978; Lycan 1986; Crimmins 1992; Manfredi 1993; see also Dennett 1987 for a critical perspective). Not all of them regarded it as a problem, exactly. Some regarded it as a discovery. But as a discovery, it proved useless: The literature on tacit belief petered out, rather than proving fruitful.

We can enter the Problem of Tacit Belief by noticing that it’s not wholly implausible that people have infinitely many beliefs. Suppose Cynthia believes that there are a few beers in her fridge. She also believes, presumably, that there are fewer than 100 bottles of beer in her fridge. She therefore also seemingly believes that there are fewer than 101 bottles, and fewer than 102, and fewer than 1,000, and fewer than 1 million, and fewer than 16,423,300.6, and so on. If we accept that Cynthia does in fact believe all that (presumably, she would readily assent to those propositions if asked, be surprised to learn they were false, and rely on them implicitly in her actions), then she has infinitely many beliefs about the number of beers in her fridge. However, it is implausible that each of these beliefs is grounded in a separately stored representational content.

Thus was born the distinction between core beliefs, those that are explicitly stored and represented, and tacit beliefs, those whose contents are swiftly derivable from the core beliefs. Suppose Cynthia has a stored representation with the content there are four bottles of Lucky Lager in the refrigerator door. This is her core belief. From this core belief, an infinite number of tacit beliefs are now swiftly derivable: that there are fewer than five bottles of Lucky Lager in the refrigerator door, that there are fewer than six bottles, and so forth, and also (given that she knows that Lucky Lager is a type of beer) that there are four bottles of beer in the refrigerator door, and also (given that she knows that whatever is in the refrigerator door is also in the fridge) that there are four bottles of Lucky Lager in the fridge, and also (given that she knows that Lucky Lager is cheap) that there are a few bottles of cheap beer in the fridge. Nearly all of Cynthia’s many beer-in-fridge beliefs might be tacit, grounded in just a few core beliefs.

Although postulating a core/tacit distinction helps the representationalist avoid populating the mind with infinitely many mostly redundant stored representations, a band of merry troubles follows.

First, it’s worth noting that this maneuver constitutes a substantial retreat from Presence. As formulated, in the normal or standard case, when someone believes that P they have a stored representation with the content P. I don’t think it is uncharitable to characterize representationalists as tending to say this; it’s very much how they ordinarily talk. But now it looks like the vast majority of our beliefs might be abnormal or nonstandard. Even setting aside the cheap infinitude of large numbers, Cynthia plausibly has a billion closely related beer-in-the-fridge beliefs (e.g., at least three Lucky Lagers in the fridge door, at least three cheap beers in the kitchen, about four bottled beers in the usual place; imagine nine variables [location, price, brand, number, duration, container type...] each with ten independent values). It would be shocking if even 1% of these billion beer beliefs were explicitly represented: That would be 10 million distinct stored representations for this one minor set of facts about the world. Many other beliefs surely range into the tacit millions or billions: My belief that my wife and I started dating in grad school, your belief that racism was prevalent in Louisiana in the 1920s, Ankur’s belief that there’s a gas station on the corner of University and Iowa. Each of these beliefs has many, many close neighbors, in combinatorial profusion -- many more neighbors, largely redundant, than it’s plausible to suppose exist as distinct, robustly real, stored representations. At best, the “normal” case of having a stored representation with exactly the content P when you believe that P is a rarity. Furthermore, we don’t distinguish core beliefs from very nearby tacit ones in our ordinary belief attribution, and there is no practical reason to do so.

Suppose the representationalist acknowledges this, modifying Presence appropriately: To believe that P, in the standard case, is to have a stored representation from which P is swiftly derivable. Now they face the complementary challenge of resisting the conclusion that we believe huge numbers of propositions it’s implausible to suppose we believe. To determine if a number is divisible by 3, add its digits. If the sum of its digits is divisible by 3, then the number itself is. Knowing this, the proposition 112 is not divisible by 3 is now, for you, swiftly derivable from propositions that you explicitly represent. But unless you’re the type of person who spends a lot of time thinking about what numbers are divisible by what others, it seems that you don’t believe that proposition before actually doing the calculation. Before doing the calculation, you are, so to speak, disposed to believe that 112 is not divisible by 3. But believing is one thing and being disposed to believe is quite another (even if the distinction is fuzzy-bordered; Audi 1994). The belief/disposition-to-believe distinction is decidedly not the core/tacit distinction the representationalist wants and needs. Still worse, if we have any conflicting representations, it will arguably turn out that we tacitly believe literally everything, if everything follows from a contradiction -- and presumably swiftly enough given the rules of reductio ad absurdum.

Furthermore, postulating a core/tacit distinction requires abandoning empirical evidence for the sake of an ungrounded and possibly untestable architectural speculation. It requires that there be an important psychological difference between your core beliefs and your tacit ones. Either Cynthia stores there’s beer in the fridge, leaving tacit there’s Lucky Lager in the fridge, or she stores there’s Lucky Lager in the fridge, leaving tacit there’s beer in the fridge, or she stores both, leaving neither tacit, or she stores neither, both being quickly derivable from some other stored representational content. Cynthia’s billion beer beliefs divide sharply into a few core ones and a plethora, presumably, of tacit ones. But no evidence from cognitive science speaks in favor of sharply dividing our beliefs into those that are core and those that are tacit. Indeed, it’s hard see how such a claim could realistically be tested. Might we, for example, look for different response times to questions about beer versus Lucky Lager? Maybe that would be a start. But it seems unlikely that we could really separate out such patterns from linguistic processing time and other sources of difficulty or facilitation of response. Could we look for higher levels of activity in brain regions associated with explicit inference? Maybe. But again, there are many reasons that such regions might be active when considering whether there is beer in the fridge.

To avoid an impossible proliferation of representations, the industrial-strength representationalist needs a sharp distinction between core and tacit beliefs. But the distinction has no practical importance, doesn’t map onto ordinary patterns of belief attribution, and has no empirical support, and it’s unlikely that we could even realistically test for it with existing methods. It’s a useless posit of a fake difference, a pseudo-distinction required when the representationalists’ simplistic theory crashes against our unsimple world.

[a visual representation of one of my favorite beliefs; image source]