Weisberg’s Explanatory Optimism via Automated Compression Theory

Philosopher Josh Weisberg expresses “explanatory optimism about the hard problem of consciousness” by arguing that a physicalist explanation of phenomenal consciousness remains a plausible and positive path. He contends that the hard problem looks hard because first-person appearances are systematically misleading. It is not an unsolvable metaphysical riddle but rather an “epistemic” one, buried in the way consciousness appears to us from a first-person perspective.

Instead of conjuring up new, unique, and perhaps nonphysical properties to account for consciousness, Weisberg suggests we should question the “epistemic underpinnings of the problem,” which are the “appearances and intuitions driving this intense explanatory pessimism.” He marvels at what seems to him “to be highly plausible and well-motivated physicalist explanations of phenomenal consciousness” that “can be viewed by others to be complete and utter non-starters, to put it mildly” (Weisberg, 2025, 2023).

Debunking Argument and Weak Illusionism

Weisberg’s central thesis is a “debunking argument” that challenges the evidential status of first-person access to consciousness by “undercutting the evidential status of those appearances,” undercutting “the justificatory link between the first-person appearances and our hard problem intuitions.”

The argument begins as follows:

1. There is a plausible explanation of how consciousness appears in first-person access making no reference to exceptional properties.
2. If there is a plausible explanation of how consciousness appears in first-person access making no refer to exceptional properties, how consciousness appears in first-person access loses its status as a justifying ground for a belief in exceptional properties.
3. Therefore, how consciousness appears in first-person access loses its status as a justifying ground for a belief in exceptional properties. (Weisberg, 2025)

(Obviously, the argument hangs by the “rope,” or by the “thread,” of the first premise.)

Weisberg argues that without these “first-personal justifying grounds,” the hard problem is difficult to motivate. His strategy follows the broad outline of Derk Pereboom's “qualitative inaccuracy hypothesis,” which suggests that first-person access may be misleading about the “qualitative natures of phenomenal properties.” However, Weisberg aims to provide a specific empirical theory to account for this inaccuracy.

Weisberg refers to his position as “weak illusionism,” which posits that while consciousness exists, we are mistaken about some of its properties. This contrasts with “strong illusionism” (“there is nothing it’s like to be us”), which claims that phenomenal consciousness itself is an illusion (Illusionism), and from which Weisberg distances himself. In other words, weak illusionism is “the claim that there is indeed something it’s like for us in conscious experience, but we are in error about some of the properties of consciousness.” It rejects only the “‘revelatory’ claim that we have highly justified access to the underlying metaphysical nature of consciousness.”

DISC Properties and the Problem of Appearances

Weisberg identifies four main “culprits” or phenomenal features that prompt our “hard problem intuitions” and belief in “exceptional properties.” He refers to these as “DISC” properties:

• Direct: Experiences are accessed in a seemingly direct way.
• Indescribable: They seem to have features that are indescribable in informative terms.
• Simple: They seem to be constituted by simple properties, “in no way further decomposable.”
• Contingent: Their properties seem only contingently connected to other, more tractable features of mind and world. (Weisberg, 2025, 2023)

Weisberg admits that “if conscious experience seems DISCy, then the standard thought experiments used to attack physicalism will seem plausible. DISCyness explains why zombies seem (positively, primarily, ideally) conceivable, why Mary seems to gain propositional knowledge on her release, why there seems to be an other-minds problem, etc.” He recognizes, “The problem of specifying the appearance of our conscious experience, particularly those elements leading to hard problem intuitions, is a difficult one” (Weisberg, 2025, 2023).

Automated Compression Theory (ACT)

The key step in Weisberg’s debunking argument involves the development and defense of an empirical model of first-person access: Automated Compression Theory (ACT). “ACT holds that first-person access to consciousness is accomplished by automated accessing of compressed sensory information. Because of the distorting nature of this compressed access, it seems to subjects that consciousness possesses ‘exceptional’ properties—properties leading to the hard problem—even though no such properties are present. If there are no exceptional properties to explain, then an explanation in easy terms can fully account for conscious experience” (Weisberg, 2023).

Thus, Weisberg suggests that if his characterization is correct, his argument “requires a plausible explanation of DISC appearances in easy, physical-friendly terms,” and he claims to “build an empirical case for an easy explanation of the DISCy appearance of phenomenal consciousness” based on the ACT perspective that “when we consider our conscious experience from the first-person perspective, we automatically access compressed information chunks, and this process explains our hard problem intuitions in easy terms.” Weisberg continues by claiming, “There is strong empirical evidence that at many levels of mentality, we find automatic and compressing processes” (Weisberg, 2025, 2023).

Weisberg states that his ACT is grounded in empirical evidence for two widespread processes in the brain:

1. Automaticity: Many mental processes are automatic, quick, and subjectively inaccessible to us, making the information they deliver seem direct and unmediated.
2. Compression: The brain is under “neuro-engineering pressure” to consolidate and compress information into efficient packets. This process condenses mental information into “dense chunks” that are “at once 'thinkable' but also seemingly non-decomposable.”

Here’s how Weisberg relates the apparent hard problem of DISC to the putative easy process of ACT (brain automaticity and compression). He argues that automaticity accounts for the appearance of Directness. Compression, by hiding the complex relational nature of our mental states, makes them seem Indescribable and Simple. Furthermore, because the constitutive connections are not directly accessed, they appear only Contingently connected to the functional machinery of the mind (Weisberg, 2025, 2023).

To provide a concrete example of how this process works, Weisberg references “quality space theory,” which “holds that mental qualities are the properties of mental states accounting for their distinctive families of similarities and differences.” For instance, our perception of “red” is a relational property based on its position in the quality space relative to other colors. When this information is compressed, it doesn't present its full relational profile, making the quality seem “intrinsic and non-relational in character,” thus appearing deceptively simple and indescribable from the first-person perspective (Weisberg, 2025).

Weisberg argues ACT is not a mere “reductionist’s ‘hail Mary’” by offering “positive evidence that automated compression generates DISC appearances.” He supports ACT with empirical evidence from expert perception. For example, a chess expert can automatically access complex game features but may find it difficult to explain what they are seeing to a novice. Similarly, fluent readers see “whole words and phrases as single units,” and it takes effort to decompose them back into individual letters. This demonstrates that automated compression can make something complex and decomposable appear as simple and non-decomposable, a “seemingly simple directly-accessed chunk” (Weisberg, 2025).

Weisberg concludes that ACT, while not a complete theory of consciousness, is a “plausible add-on to any physicalist theory” because it provides a debunking explanation for why such theories might initially seem implausible. The existence of this plausible empirical explanation shifts the burden of proof to explanatory pessimists, who can no longer simply appeal to the appearances in question to rule out physicalist accounts. The path to a satisfying physicalist explanation of consciousness “remains open, if my argument is sound,” he says, adding that “the burden of proof is now on the pessimists to show why we shouldn’t be optimistic about explaining consciousness.” Weisberg’s coup de grâce is a claimed “final accounting of a disillusioned Mary: she lacks the ability to automatically access a compressed version of the information she already knows in relatively decompressed form in her room.” But the devil, he admits, remains “doubtlessly in the details” (Weisberg, 2025).