by Jeremy Pober and Eric Schwitzgebel
Twelve years ago, one of us (ES) distinguished two kinds of theories: superficial and deep. Nearly any phenomenon can be approached in a superficial or deep manner. A superficial judge of human beauty treats it as skin deep. A superficial reading of Shakespeare takes characters at their word and focuses on the obvious aspects of each scene. A superficial housecleaning ignores the backsides and undersides of household items.
And of course one can have a superficial theory of belief. Phenomenal dispositionalism is intended to be such a theory. According to phenomenal dispositionalism, whether someone believes that P is a matter of whether they have certain behavioral, phenomenal (i.e., experiential), and cognitive dispositions, specifically, the dispositions that are "stereotypical" of a person who believes that P. Compare: To be an extravert just is to have the behavioral, phenomenal, and cognitive dispositions stereotypical of extraversion.
Superficial theories contrast with deep theories. Among theories of belief, the main contrast has been with the computationalist, representationalist functionalism made famous by Jerry Fodor (1987) and recently defended by Jake Quilty-Dunn and Eric Mandelbaum.
But what makes a theory of some property P superficial (or deep)? Twelve years ago, ES offered an answer: It depends on the theory's relationship to surface properties. Surface properties are observable features of a phenomenon that a theory of P is designed to explain (in a loose sense of "observable"[1]).
What relation to surface properties must a theory have to be superficial or deep? Back in 2013, ES said that "relative to a class of surface phenomena... a property is superficial if it identifies possession of the property simply with patterns in the surface phenomena" (2013, 77). And a theory is deep "relative to a class of surface phenomena... if it identifies possession of the property with some feature other than patterns in those same surface phenomena -- some feature that presumably explains or causes or underwrites those surface patterns" (ibid.).
This definition fits our toy examples above. A superficial judge of beauty relies on the most easily observable physical patterns, a superficial reading of Shakespeare focuses on surface-level dialogue, and a superficial house-cleaning treats looking clean as clean.
However, we have reason to be unsatisfied with this definition. [ES thanks JP for emphasizing this point in a series of discussions.]
Consider poison, a "causal concept" in David Armstrong (1968)'s sense: a concept defined by its causes and/or effects. Poison can be defined in terms of biologically harming a person when ingested (with refinements to differentiate poisoning from, say, drinking lava).[2] If I explain a death by saying that a person was poisoned, you can infer that the death was caused by ingestion rather than, say, hypothermia. That's informative -- but much less informative than saying that the person ingested cyanide, because chemical types like cyanide are defined structurally, allowing detailed explanations of how they interact with human physiology.
A theory of health that only has non-structural causal concepts like "poison" (or "medicine") would be a superficial theory of health. A deep theory, in contrast, invokes underlying mechanisms.
Yet, by ES's 2013 definition, a theory appealing to poison wouldn't count as superficial, because ingesting poison isn't merely related to death as two parts of a superficial pattern. Poison causes death.[3]
In a new draft, ES proposes a revised definition: a theory of property P is superficial if "whether an entity has property [P] is determined (that is, constituted or grounded...) entirely by superficial facts about that entity", where superficial facts are readily observed facts. For causal concepts, being the cause of is a constitutive relationship. This new definition thus accommodates causal superficialism, where poisons cause death and medicines cause recoveries, as inferable from readily observable relationships (such as randomized controlled trials), without appeal to deeper structural features.
That's a good thing! Otherwise, phenomenal dispositionalism only counts as a superficial theory of belief if dispositions don't cause their manifestations. Some philosophers of mind (e.g., Ryle 1949) indeed view dispositions non-causally. But others, like Armstrong (1968), propose a "realist" conception: Dispositions are type-identical to their causal bases. Fragility, for example, is identified with the microstructural features that cause fragile objects to break when struck.[4]
In his original articulation of phenomenal dispositionalism, ES expressed willingness to accept such a realist view (2002, 273n18). This version of dispositionalism can be considered equivalent to a version of functionalism (which holds that mental states can be defined in terms of their causal relations to inputs, outputs, and other mental states). Georges Rey (1997) calls this type of functionalism superficial functionalism, where all functional/causal roles are defined only in relation to behavior, thought, experience, and "similar" states (e.g., desire is similar to belief, so a superficial functionalist theory of belief can include relations to desires).[5]
Of course, deep theories also often employ causal explanations. So if causal superficial theories are possible, what distinguishes them from deep theories? The answer is that causal posits in superficial theories have minimal explanatory content, whereas deep theories have excess explanatory content.[6] Posits with minimal explanatory content explain all that they were posited to explain and no more, whereas posits with excess content make further falsifiable predictions.
Consider the difference between a geneticist working right after Gregor Mendel published his work on heritability, and one working after Franklin, Watson, and Crick had mapped the structure of DNA and demonstrated how it instantiated genetic material. Mendel's theory, which gives us the posits of trait, gene, allele, and dominant/recessive, is a powerful theory (much like belief/desire psychology), but it doesn't explain how genes and alleles have the properties that they do. An allele is just the genetic material for a variant in phenotype, e.g., blood type A versus B or O. But in the initial Mendelian framework, it was defined as "whatever is responsible for variance in (e.g.) blood type".
[illustration of Mendel's superficial causal theory;
image source]
Contrast with someone working in the latter half of the 20th century. They know that genetic information is realized in DNA (& RNA), which via its repeating base patterns and double helix structure, acts as a base code for the information that constitutes alleles. In other words, they know how genes carry genetic information.[7]
Superficial theories needn't be acausal, but if they posit causal relationships, those relationships must exist among the readily observable features, without invoking hidden structures or mechanisms that yield additional explanatory content. In contrast, the later 20th century theory makes many more falsifiable predictions -- those that follow from the structure of DNA -- and thus has excess explanatory content.
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[1] This might not match the sense of "observable" sometimes used in philosophy of science. Dennett (1994) defines observable from his perspective of "urbane verificationism" and, for a theory of attitudes, takes the same list of surface properties to be observable as ES: behavior, thought, and experience.
[2] More precisely, poison is always a two-place predicate, poison-for-S where S is some group of organisms such as a species. When no such group is specified, we can treat instances of poison as poison-for-humans. We are ignoring contact poisons and other complications.
[3] Thus the distinction between superficial and deep theories is not a distinction about noncausal versus causal explanations. Consequently, the superficial/deep distinction as applied to the attitudes does not end up reducing to Devin Curry's distinction between beliefs as properties of persons and beliefs as "cogs" of cognitive science (Curry 2021).
[4] The standard way of defining a causal basis is in terms of physical properties, such as microstructural properties defining "fragility". However this is not a strict requirement. One can posit a mental kind (as in Quilty-Dunn and Mandelbaum 2018 where representations are the causal bases of dispositions constitutive of belief stereotypes) or even a higher-order kind (as in Prior, Pargetter, and Jackson 1982).
[5] Rey (1994; 1997) invokes this term in a debate with Dan Dennett that parallels the debate between ES and Quilty-Dunn and Mandelbaum. While the overall debate turns on different issues, the definition of superficialist theories of belief lines up. Examples of this sort of functionalism plausibly include David Armstrong (1968), the David Lewis of "An Argument for the Identity Theory" (1966) but maybe not the David Lewis of "Mad Pain and Martin Pain" (1980), and Adam Pautz 2021).
[6] Term adopted from Lakatos's (1968) notion of "excess" explanatory content.
[7] The DNA example also lets us talk about different levels or degrees of depth. The late 20th century theory of a gene is a deep one, but so is a theory mid-way between that and Mendel's. In the first years of the 20th century scientists identified chromosomes as the realizer of genes, but did not know that chromosomes were made of DNA (they thought they were proteins). This theory too is deep -- there are excess predictions made by the assignment of genetic material to chromosomes -- but not as deep as later views, because not nearly as many excess predictions were made. We can tentatively call such a theory formally deep, whereas a theory that more fully explains how the posit in question (genes, beliefs) has the properties that it does is substantively deep.