What is the impact of the Knowledge Argument against Physicalism?

2023-2 Metaphysics of the Self

 

What is the impact of the Knowledge Argument against Physicalism?

 

1. Introduction

The emergence of the philosophical concept “qualia” is widely recognized as one of the most contentious issues in the philosophy of mind. It arguably challenges “a physicalist picture of the world” (Newen et al. 2007: 147), considered the most dominant perspective allegedly providing the best explanation of our world.

Jackson’s knowledge argument is a representative of attempts to substantiate the fallibility of physicalism by employing the concept of qualia. Although a significant number of objections have already been raised against this argument, it is still controversial to determine whether Jackson has successfully refuted physicalism, or at least certain types of it. If Jackson’s argument proves to be sound, it would require the proponents of physicalism to reevaluate their claims and reconsider their entire worldview. The purpose of this paper is to survey the landscape of these debates and assert that the knowledge argument has especially undermines two central theses of physicalism.

Section 2.1 outlines Jackson’s knowledge argument and how it can threaten physicalism. In Section 2.2, I consider one of the famous challenges to the knowledge argument raised by Lewis, namely “The Ability Hypothesis.” I then argue that the attempt to exclude what Mary has learned (knowledge about the distinctive sensory quality of color) from propositional knowledge is not tenable. This failure leads physicalists to abandon a specific form of physicalism, commonly referred to as reductive physicalism. Finally, in Section 2.3, I cover the influential defense of non-reductive physicalism, which is often called “Old-Fact/New Guise Analysis.” I hold that the defense attempts by non-reductive physicalists are also unsatisfactory, and the knowledge argument ultimately constitute a threat to all forms of physicalism.

2. Mapping the Debate: the epistemological status of what Mary has known

2.1 Jackson’s Knowledge argument and its implications

To start our discussion, I would like to pose a fundamental question: What are qualia? Although the concept of qualia is occasionally downplayed by some physicalists as “a fiction of bad philosophy” (Kim 2007: 10-11), we all know what is referred to by this concept: the distinctive qualities we immediately possess, prior to acquiring the specific scientific knowledge, in our everyday sensory experiences. I accept Jaegwon Kim’s definition of ‘qualia,’ as follows:

Sensations have characteristic qualitative features; these are also called “phenomenal” or “phenomenological” or “sensory” qualities— “qualia” for short. Seeing a ripe tomato has a certain distinctive sensory quality, a quality that is unmistakably different from the sensory quality of seeing a bunch of spinach leaves (Kim 1996: 114).

Traditionally, humans have delineated such phenomenological qualities as manifest images. As Sellars points out, the manifest images of man-in-the-world, take cognitive precedence over scientific images, which often erode the explanatory power of a worldview that seeks to explain everything through a single unitary theory (cf. Sellas 1991: 1-40). Similarly, Russell had already argued persuasively, ahead of Jackson, that “a blind person with complete propositional knowledge of the physics of the universe” could still be ignorant of manifest images such as the difference between red and blue (Landini 2019: 194).

It is worth noting that even the most rigorous defenders of physicalism have no doubt about the existence of such images, which seem distinct from scientific ones; denying these images would simply degenerate into skepticism. Instead, they would argue that just as having a pain is reducible to the firing of C-fibers, all qualia would be reducible to corresponding physical properties. The implication of this claim is twofold. First, that our world is entirely composed of physical facts. Second, events that appear to be non-physical (e.g., mental states) can be explained physically after reduction. Accordingly, we can summarize the two main theses of physicalism as follows:

(i) The ontological thesis of physicalism: Every fact in the world is physical.

(ii) The epistemological supremacy thesis of physicalism: The manifest images and their components are reducible to the scientific images and their corresponding components (the physical properties, relations, and entities). Therefore, physics can explain every image (including the image of mental state) in a complete way.

Devising a simple and ingenious thought experiment, Jackson tried to demonstrate that both theses were fallacious. The story goes something like this^[각주:1]: Mary, who knows all the physical facts about us and our environment, has never seen any color because she has lived in black-and-white room from birth. When she is let out of the black-and-white room and finds a bright red rose, she would have learned something new, what it is like to see something red from this visual experience. If so, what Mary has learned cannot be classified as physical knowledge and, consequently, cannot be derived from physical facts. Therefore, the knowledge argument can be formulated as follows:

(i) Mary possesses knowledge of all the physical facts about us and our environment, despite never having seen any colors.

(ii) Mary can experience seeing the color “red” and gain new knowledge, specifically the qualia of the color “red”, from this subjective experience (“what it is like to see something red”).

(iii) Therefore, Mary can acquire new knowledge about non-physical facts.

(iv) Physicalism claims that every fact in the world is physical.

(v) Consequently, physicalism is flawed and cannot provide a complete explanation for mental states.

Because this argument is valid, physicalists must abandon two theses of physicalism unless they reject one or more of the premises.

2.2 The Ability Hypothesis and the Analysis of “knowing how.”

Physicists’ responses to Jackson’s knowledge argument can be broadly divided into two main categories. Some physicists uphold both the ontological thesis and the epistemological supremacy thesis of physicalism. They argue that the knowledge argument has not affected both theses because Mary’s distinctive and novel qualities of the experienced color cannot even be considered as knowledge about facts (i.e., propositional knowledge). The other physicists espouse the ontological thesis of physicalism and maintain that what Mary has acquired is a specific form of propositional knowledge but not about non-physical facts. Whichever stance they adopt, the main target of their counterexamples is to debunk the inference from premise (ii) to premise (iii).

Lewis raises questions about whether what Mary acquires in premise (ii) can be classified as propositional knowledge, which pertains to knowledge about facts. According to Lewis, what Mary has gained is a kind of knowledge-how involving the ability to imagine, recognize, and remember experiences. For instance, if I have never tasted Vegemite before, I cannot have any memories of its taste or imagination what it tastes like. Likewise, until I learn about the taste of Vegemite through direct experience, I won’t be able to recognize it in future foods. Of course, such abilities do not weaken the completeness of propositional knowledge about Vegemite.

The Ability Hypothesis says that knowing what an experience is like just is the possession of these abilities to remember, imagine, and recognize. It isn’t the possession of any kind of information, ordinary or peculiar. It isn’t knowing that certain possibilities aren’t actualized. It isn’t knowing-that. It’s knowing-how (Lewis 1988: 288).

Lewis’s suggestion, however, faces the objection that specific propositional knowledge has already been given to Mary when she acquires knowledge-how. Stanley and Williamson’s analysis shows that gaining certain ability amounts to acquiring corresponding propositional knowledge. Let’s consider the sentence “Mary knows when the black and white TV will turn off.” This implies that Mary possesses propositional knowledge that “the black and white TV turns off at tº” in the first place. Likewise, the sentence “Mary knows how to turn off the black and white TV” implies that Mary already possesses propositional knowledge that “the way to turn off the black and white TV is wº.” This essentially means that what Mary has learned through her visual experience of the color “red” can be reduced to specific propositional knowledge.

Our discussion shows […] that Lewis’s account is incorrect. Knowing how to imagine red and knowing how to recognize red are both examples of knowledge-that. For example, x’s knowing how to imagine red amounts to knowing a proposition of the form ‘w is a way for x to imagine red’, entertained under a guise involving a practical mode of presentation of a way (Stanley and Williamson 2001: 442).

To sum up: If we cannot deny that what Mary has learned is propositional knowledge, then Jackson’s conclusion, which asserts the existence of facts beyond physical facts represented by such propositional knowledge, remains unchallenged.

2.3 Old-Fact/New Guise Analysis and its soundness

If the knowledge Mary has acquired is derived from facts, one possible response that physicalists can take is to argue that these facts are still physical in nature. This approach is known as the Old-Fact/New Guise Analysis, and the fundamental idea behind this argument shares similarities with Frege’s distinction between the sense (Sinn) and reference (Bedeutung) (cf. Frege 1997: 151-171). For instance, Jameson can know the fact that Peter Parker is a white male but does not know whether Spider-Man is a white male. This is because “Peter Parker” and “Spider-Man” share the same reference, but their senses can be given differently.

The idea that the same fact can be differently known in various ways shows that we do not need to abandon the ontological thesis of physicalism. This is because the same old physical facts were simply disclosed to Mary through a different mode, namely her visual experience (Horgan 1984: 151-152). Before taking a further step, it is worth noting that a certain type of physicalism is discarded as a corollary of adopting this strategy: a reductive physicalism. For the claim there are various physical and non-physical representations of physical facts amounts to conceding the existence of unique knowledge in fields like psychology or phenomenology, which cannot be obtained through physics alone.

From a non-reductive standpoint, however, the situation is not entirely optimistic. As Alter points out, there is a significant difference between the case of Mary and that of Jameson: while Jemson doesn’t need to know who “Spider-Man” or “Peter Parker” refers to, to know that the referent of these names is a white male, the allegedly new guise, “what it is like to see something red,” seems sine qua non of knowing any facts about the experience of seeing red. In this respect, Alter claims the Old-Fact/New-Guise Analysis is no better off than the Ability Analysis in terms of intuitive plausibility (Alter 1998: 42). He said:

One of the facts relevant to the Mary case is, in Old-Fact/New-Guise terminology, that the experience of seeing red has the phenomenal guise G. The Old-Fact/New-Guise Analysis depends on the claim that it is possible to know that fact even if, as in the case of the pre-release Mary, G is not in one’s representational repertoire. That claim is doubtful. G figures into the fact that seeing red has G so centrally that it seems implausible that one could know it without having G at one’s cognitive disposal (Alter 1998: 43)

If this analysis is correct, we would acknowledge that the way Mary gains knowledge is a pathway to new facts, not old ones because Mary couldn’t access such a guise before leaving the room.

3. Conclusion

Despite some noteworthy counterarguments, we have concluded that these objections do not substantially undermine Mary’s case. As a consequence, Jackson’s knowledge argument indeed poses a significant challenge to two key tenets of physicalism, particularly eroding the foundation of reductive physicalism, which aims to provide a comprehensive explanation of the entire world through a single physical theory.

References

Alter, T. (1998), “A Limited defense of the knowledge argument,” Philosophical studies 90: 35-56.

Frege, G. (1997), “On Sinn and Bedeutung,” in: The Frege Reader, M. Beaney (ed.), Oxford: Blackwell.

Horgan, T. (1984), “Jackson on Physical Information and Qualia,” The Philosophical quarterly 34: 147-152.

Jackson, F. (1982), “Epiphenomenal Qualia,” Philosophical Quarterly 32: 127-136

Jackson, F. (1986), “What Mary Didn't Know,” The Journal of Philosophy 83: 291-295

Kim, J. (1996), Philosophy of Mind, Boulder, CO: Westview Press.

Kim, J. (2007), Physicalism, Or Something Near Enough, Princeton, New Jersey: Princeton University Press.

Landini, G. (2019), “Fitch and Mary,” Axiomathes 30:193-199. 

Lewis, D. K. (1988), “What Experience Teaches,” Proceedings of the Russellian Society 13, 29-57. Reprinted in Papers in Metaphysics and Epistemology. Cambridge: Cambridge University Press, 1999.

Newen, A., Hoffmann V., and Esfeld M. (2007) “Preface to Mental Causation, Externalism and Self-Knowledge,” Erkenntnis 67: 147-148.

Sellars, W. (1991), “Philosophy and the Scientific Image of Man,” in: Science, Perception, and Reality, Atascadero, California: Ridgeview Publishing Company. 

Stanley, J., and Williamson T. (2001), “Knowing How,” Journal of Philosophy 98: 411-444.

1. The example presented here originated from Jackson’s following articles (Jackson 1982: 130; Jackson 1986: 291). [본문으로]