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Phenomenology and the unity of consciousness

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The phenomenology of the unity of consciousness can be analyzed in terms of perceptual spatial and object unity. Subject unity—what we commonly understand by “the unity of consciousness”—has no attendant phenomenology. The further, non-phenomenological, effects of unity can be analyzed in terms of the functional notion of access unity. The unity of consciousness in general can therefore be analyzed in terms of access unity. As a consequence, we can avoid the theoretical introduction of problematic notions such as subsumptive or phenomenal unity.

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  1. The arguments in this paper are confined to synchronic unity. Diachronic unity is a further question.

  2. I mean here theories which understand consciousness to be, in the first place, a matter of the processing of representations with first-order (i.e. external, non-mental) content. Examples of this type of theory include Baars (1989), Dennett (1991), Dretske (1995), Prinz (2012). The motivating arguments do not depend on an acceptance of this theory. One could agree that there is no phenomenology to unity per se, yet reject the further claim that the unity of consciousness can be analyzed in terms of access unity. Hill (1991, 2014, 2018), for example, rejects a notion of a phenomenology of unity but does not analyze unity in general as access unity. Furthermore, I would reject more speculative types of phenomenology, such as cognitive phenomenology, or representational theories such as Shoemaker (1994) on which theoretical room is made for properties of experience, which could, perhaps, be employed to deal with a phenomenology of the unity of consciousness, although the theory presented is not incompatible with these theories.

  3. Without recourse to controversial notions of unity such as that proposed in Tye (2003). See Sect. 5 for discussion.

  4. It is part of Hill’s theory that unity can be partial and that there can be disunity. As mentioned above, my account is neutral on these questions.

  5. Let me emphasize a clarification. I am not arguing that all unity is spatial or objectual. This is more or less an indefensible position as there are cases of unity in which there is no plausible spatial or objectual content (see, e.g., Roelefs 2014 for a list). Rather, I am arguing that the phenomenology of unity can be accounted for in terms of the contents of object and spatial unity within perception.

  6. One could ask whether the account is eliminativist, a term I scare-quoted above, or reductionist about the unity of consciousness and the phenomenology of unity. If one can helpfully distinguish between these two notions for all individual cases, the most natural reading is that the account reduces unity to access unity, reduces the phenomenology that does result from unity to the contents of perceptual spatial and object unity that it introduces, and eliminates a phenomenology of unity per se.

  7. As a result of properties being bound together in sub-personal processing, they are consciously represented differently than they would be were they delivered to conscious experience unbound. In a discussion of the binding problem, Garson (2001) argues presuasively that once the binding problem is solved at the physical level of implementation, there is no further phenomenological problem that remains. I find such an argument quite convincing. Binding has a representational consequence—this is what binding does—and that is all that there is to say. Why would there need to be phenomenological binding over and above representational binding? The same point applies to “functional binding”. Once two functional properties are appropriately located within the same functional nexus, what more would be required for unity? There remains the tricky question just alluded to as to exactly how bound contents articulate the representation of objecthood. However, this is not really a problem of “phenomenal binding”, as each option equally well binds, but of carefully describing our conceptual scheme as it appears to us in experience. For example, the two formulations used above—that there is an F G object at l or that the object at l is an F G—are different in their logical construction and therefore in their representation of the basics of our conceptual scheme as regards the structure of the external world. We must, therefore, be careful when it matters which formulation is the correct one, such as when we are considering questions about the philosophy of language or mental content, or some issues in metaphysics. But these questions are not relevant here.

  8. It is also not clear if and how the acceptance of cognitive phenomenology would bear on the present discussion, as the relevant spatial and object unities seem to me to occur within perception and thought, not across the boundary. I, at least, cannot come up with a case where a perception and a thought could be said to be phenomenologically unified in the paradigm intra-perceptual way. One may argue that cases of induced or acquired seeing-as might do the trick, but these can be handled as follows: a conscious thought may cause an experience to acquire extra content, but this extra content does not link the thought and experience in the way that spatial and object unity links the contents within perception through further perceptual content. In addition, cross or multi-modal experiences would also seem likewise to raise no such problem. However, if one insisted on there being a phenomenology of thought, then one could hold that the extra content that results in cognitive analogs of perceptual binding are cases of a phenomenology of unity within thought. Nevertheless, I do not think it proper to talk of a phenomenology of thought, although I will not press the point here as this does not affect my main point that there is no phenomenology to unity per se, only to the content introductions within perceptual unity.

  9. I will refer to object and spatial unity as “perceptual”, keeping the qualification that this also covers phenomenologically encapsulated perceptual imagination and memory implicit.

  10. One might argue that introspection itself could provide a counterexample to this claim. When one introspects, one knows that any two introspected experiences are one’s experiences, but this knowing is not based on a recognition of a phenomenological feature of one’s stream of consciousness but rather a simultaneous noticing of two conscious states. And this noticing is, in turn, just another conscious state that one is in—one whose unity with the others does not result in any phenomenology.

  11. The phenomenology of proprioception is, likely, more complicated, but as I believe that it is fundamentally the same as external perception, I will assume here that it can be treated in the same manner.

  12. The ability to A does not require the further ability A' to exercise the ability to A. The ability—or, rather, “ability”, as ordinary talk misleads here—to exercise an ability is not really a further ability that one possesses, only when as a matter of fact one can exercise the original ability. To take this line would be to set off on a regress.

  13. One could perhaps attempt to argue that in this scenario were I to be in possession of a tool with which to reach both the handles of the door and window, or longer arms, or the window and the door were closer together, and so on, I would be able to exercise both abilities simultaneously, whereas this is not so in the Sperling case and thus there is a disanalogy. But the Sperling case, like all access bottlenecks, arises because of a limited information processing capacity. Were I to have this capacity extended, an extension that is in principle no different from an arm extension, I would be able to exercise the abilities to report that p and that q simultaneously and thus there is no disanalogy.

  14. Following on from footnote 12, I think it similarly mistaken to hold that being able to express the abilities A and B together is a further ability over and above the abilities to A and to B. If I can open the door and also whistle, I do not possess three abilities—to open the door, to whistle, and to be able to express the abilities to open the door and whistle. If this were so, the abilities that one possesses would both quickly multiply, and the regress problem mentioned in footnote 12 would also reappear. This means that the objection that access unity in the bottleneck case should account for the ability to express the abilities to report on the three rows jointly would be mistaken for these reasons.

  15. A reviewer observes that one could argue that the Sperling experiment shows that there is a limitation on parallel processing, and then extend this to a limitation on having certain joint experiences. One could understand this as the view that the subject can experience (the majority of the detail of) each row individually but that the limitation of parallel processing means that they cannot experience (the majority of the detail of) all rows together. One might cast this as a case of switching between the rows or attending to different rows. One thinks that one has an overall experience of all three rows to the same degree of detail that one has of the row that one is attending to at any one time, but this in fact not so. Thus there is no unified experience at any time with same level of detail for all three rows. One row is privileged, so to speak, and the other two rows have a corresponding reduction in detail. This is of course, an empirical question, but it is an ingenious response to the Sperling case. Were this to be correct, it would save the access unity account from the objection. However, even if it is not correct, the presented view can account for the overall experience of all three rows. On this view, it is the unified poise of the experiences that explains the unity of the overview experience of the grid. The limitation in parallel processing comes downstream, when the subject tries to simultaneously express the abilities thus jointly conferred.

  16. Thanks to the three reviewers for pressing on this point. One reviewer comments that there may be split brain cases where the unity of consciousness breaks down but there is still some sense in which there is simultaneous accessibility. The central question about such a potential case is how the functional nexuses in which the two states are poised are related. Analyzing the unity of consciousness in terms of access consciousness is extremely flexible for handling such cases (see §5 and §6).

  17. Bayne (2010: pp. 261–262) inquires as to whether there are empirical cases of spatial disunity in sufferers of heautoscopy who simultaneously retain their normal subjective point of view while also seeming to perceive themselves from an external perspective. The following remarks apply equally to empirical cases—these, or others if they are genuine cases—as to theoretical cases.

  18. Although, in his discussion of the bottleneck objection, Hill (2018) comments that access unity is “plausibly” sufficient for the unity of consciousness but its necessity is an open question (2018: 8), and he proposes that the “gists” of experiences being extractable in bottleneck cases might allow an access-unity theory to answer the bottleneck challenge. Nevertheless, he goes on to advocate the multiple-relations theory of unity and therefore rejects, at least for the moment, an access-unity theory.

  19. Hurley (1998) argues that on a functional-representation theory, the unified contents must be semantically coherent, i.e. lacking in contradiction, and so on. This would raise some problems, perhaps, for a view like Tye’s but Bayne (2010) argues persuasively that this condition is not necessary.

  20. For example, Dainton (2010), Masrour (2014) and Lee (2014).


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I would like to thank members of audiences at Hokkaido University, Huaqiao University, and Hiroshima University, in particular Tim Bayne, for their helpful comments and suggestions, and also Akiko Frischhut for detailed discussion and comments on previous drafts.

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Peebles, G. Phenomenology and the unity of consciousness. Synthese 199, 5455–5477 (2021).

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