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On the Existence of an Explanatory Gap

By Edited Jun 26, 2016 0 0

The premise as to whether an ‘explanatory gap’—the idea that consciousness and human experience cannot be fully explained by merely identifying physical processes—exists has been at the forefront of philosophical debate for decades. As a result, philosophers are frequently critiquing past hypotheses in favor of newfound assertions that stem from predominant contemporary logic. However, in spite of recent scientific development in the postmodernist age, the ‘explanatory gap’ and the subsequent entailments that coincide with its existence or lack thereof are hardly universally agreed upon. Herein, I will attempt to discern the aforementioned dilemma in a concise manner. In Part I, I will propose the existence of an ‘explanatory gap’ by acknowledging the irremovable presence of subjectivity in respect to qualia processing—thus implicating that perfect knowledge of the physical facts could never be a sufficient means of predicting a person’s conscious states. And in Part II, I will claim that the existence of an ‘explanatory gap’ implicates that mental phenomena are non-physical and separate in relation to the physical world—therefore dispelling physicalism and adhering to the fundamental principles of ontological dualism.

PART I           Before I begin to explain why it appears that an ‘explanatory’ gap exists, it is important to establish the principle of qualia—the ‘what it feels like’ experience—and its relation to the notion of an ‘explanatory gap.’ Simplistically, if there was no ‘explanatory gap’ and experience could be explained solely through physical processes, then the supposition that any mental state of x is synonymous with the physical process y would solidify any discrepancies pertaining to what it feels like to be x. For example, the  mental state of pain would be synonymous with the physical process of the firing of C-fibers, and accordingly what it feels like to be in pain could be explained by x or y. As philosopher David Papineau, an advocate of the belief that there is no ‘explanatory gap’, claims, “It is simply this inability to free ourselves from dualist thinking that makes us think that something is unexplained in the mind-brain cases” (Papineau 2011: 9).  Adversely, what Papineau and the majority of materialists fail to acknowledge is the subjectivity of qualia; indeed, the mental state of x may derive from the physical process y, but a world without an ‘explanatory gap’ would entail that this mental state of x could always be explained by the physical process y.

A world without an ‘explanatory gap’ therefore claims that there is a universally predictable pattern between mental consciousness and physical processes; this is mistaken because people who may have the same physical processes occurring will act differently according to biased preconceptions. As Thomas Nagel asserts, “They [universally determined mental state x being explained by the physical process y] fail because if we construe the reference of mental terms to physical events on the usual model, we either get a reappearance of separate subjective events as the effects through which mental reference to physical events is secured, or else we get a false account of how mental terms refer” (Nagel 1974: 657). In regards to the example directly from Nagel’s text, a human could know everything about the physical processes of a bat’s sonar system, but still never consciously comprehend ‘what it is like’ to be a bat (Nagel 1974: 654). Similarly, one could have the knowledge that pain is caused by the firing of C-fibers in all human-beings, but never know ‘what it is like’ to feel pain from another person’s perspective (who surely copes with pain in a different way).  Physical facts may arguably explain a person’s mental state, but it is irrational to claim there is not an ‘explanatory gap’; for, physical facts do not make it possible to predict a person’s conscious states when conscious states are dictated by the typically correlational—yet still unpredictable—subjective effects of qualia.

To further illustrate why an ‘explanatory gap’ exists, one can also consider the Water vs. Qualia scenario presented by philosopher James Levine. In order to facilitate the process of explaining Levine’s conclusions, I am going to reprint his proposed scenarios below, and refer to the numbers of each step in future analysis:

ESI: Boiling Point of Water
(1) H2O molecules exert vapor pressure P at kinetic energy E
(2) At sea level exerting vapor pressure P causes molecules to rapidly escape into air
(3) Rapidly escaping into air is boiling
(4) 212o F. is kinetic energy E
(5) Water is H2O
(6) Water boils at 212o F. at sea level

ESII: Presence of Reddish Qualia
(7) S occupies brain state B
(8) Occupying brain state B is to experience a reddish quale (state R)
(9) S is experiencing a reddish quale

(Levine 2000: 1).

In the scenarios, (1) – (5) proves (6) and (7) – (8) proves (9), and, according to Levine, ESI has no ‘explanatory gap’ whereas ESII does. The objection that Levine responds to claims that Levine did not adequately explain how (5) is validated, and therefore, “If (5) requires no explanation, then neither should (8). Thus, there is no explanatory gap between the mental (conscious experience) and the physical” (Levine 2000: 1). However, where the objection goes wrong is in the presumption that (5) is not adequately explained in accordance with fundamental scientific law. Since (5) is a fact—there is no possible way to deny that water is H2O— its physical properties do not need to be explained since Levine would just be reiterating accepted knowledge—hence no ‘explanatory gap.’ ­In contrast, (8) cannot be adequately explained, because the perceptive response will always be unpredictably subjective. (5) and (8) are not comparable because (5) has factual, physical precedents whereas (8) cannot have a precedent (qualia is not predictable). As Levine summarizes, “(8) is a gappy identity, manifest by the fact that a request to explain it seems to be quite intelligible. So, given the intelligibility of a request to explain it, our inability to explain leaves an explanatory gap. Thus, the difference between the two explanation sketches is just this. The one that leaves an explanatory gap is the one that relies essentially on a gappy identity!” (Levine 2000: 1). Trying to dispute the factuality of ESI is counterintuitive, while ESII could be endlessly debated because it is certainly plausible that person A cannot fathom the quale perception and reaction of person B to reddish qualia. ESI is factual and can be indisputably explained while the processes of ESII cannot be objectively explained in non-mental terms; alas, the existence of an ‘explanatory gap.’

PART II          Now that the existence of an ‘explanatory gap’ has been established, one must determine what this means regarding the mind-body relation. Otherwise, advocates of the ‘explanatory gap’ risk being labeled distrustful of science and contently ignorant. And furthermore, simply because we cannot currently explain the mental in physical terms does not prove that the mental could never be explained in physical terms. Consequently, it is first necessary to dispel the notion of physicalism—which is, after all, often self-regarded as the realist approach to the aforementioned mind-body relation. To do this in a succinct manner (since I have already made similar points in Part I), I would like to reference philosopher Frank Jackson’s Knowledge Argument (Jackson 1982: 127-136). Even though Jackson retracted the argument, I still believe that, although Mary knew everything there is to know about colors, there is no substitute for the ‘what it is like’ feeling. She may have even envisioned color in her mind perfectly prior to physically observing color, but she will still experience a subjective feeling that cannot be rightfully explained or predicted prior to that particular moment in time. Matter alone could not prepare her for her personal reaction to color—which is remarkably different for all peoples. Hence, the existence of an ‘explanatory gap’ denies materialism.

            Thus far, I have proposed that an ‘explanatory gap’ exists, and that materialism is inadequate in explaining the mind-body relation. Accordingly, there must be a dualist relationship between the mind and body, but merely acknowledging dualism does not sufficiently settle anything. If the fundamental goal of philosophy is to explain the nature of the world around us—as opposed to how the world works which is supposed to be answered by science—then my final proposition is that a form of ontological dualism exists. Clearly, the subjectivity of life makes it impossible to simply propose that the mind and the physical are one in the same—but the unavoidable connection should not be overlooked. For from an objective perspective, the mental can only be explained in terms of the physical. Subjectivity, of course, makes the idea that the mental can be explained solely in terms of the physical fallacious. Therefore, and summarily, an ontological perspective should be adopted because ontological dualism respects that physical processes are humanity’s common denominator, while also respecting the paramount principle that subjective consciousness, presenting an ‘explanatory gap,’ is the way in which humans determine genuine meaning and factual evidence in the world.


Jackson, Frank. “Epiphenomenal Qualia”. Philosophical Quarterly. 127-136. 1982.

Levine, Joseph. “Conceivability, Identity, and the Explanatory Gap”. Cognet.mit.edu. 1. 2000.

Nagel, Thomas. “What Is It Like to be a Bat?”. Metaphysics a guide and anthology. 648-658. 1974.

Papineau, David. “What Exactly is the Explanatory Gap?”. Philosophia. 5-19. 2000.



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