Higher-Order Thoughts and the Unity of Consciousness

Most of the time our attentions are directed outwardly at the world around us and not on our inner, experiential lives. Our conscious experiences are ever present and, for many, a mundane feature of existence. But conscious experience is a rich and multi-faceted phenomenon. For the curious and reflective, it is a seemingly limitless object of study. In recent decades, we have been presented with numerous examples of subjects whose experiential lives appear to be markedly different than our own. When we contemplate what it might be like to be one of these subjects, it becomes apparent that our own experience is unified in ways that we were previously unaware of or deemed entirely unremarkable. And once we suspect that certain features of our experience may not be ubiquitous, we look for an explanation. What is responsible for the unity of consciousness? A fair bit of work has been done cataloguing the different kinds of conscious unity, but work on attempting to uncover the mental mechanisms responsible for them is still in the early stages. Rosenthal is most known for his higher-order thought (hot) theory of consciousness, but he has also extended his theory to account for conscious unity. This essay is a critical examination of Rosenthal's account. I will argue that it fails as a general account of conscious unity. The discussion will focus on Rosenthal's account, but it will have broader implications. One need not be a higher-order theorist to be tempted to use elements of Rosenthal's account to explain conscious unity. Many of my criticisms will apply whether those elements appear within the context of a higher-order theory of consciousness or not.The essay will begin with a brief discussion of some different kinds of conscious unity and a presentation of Rosenthal's account. The critical portion of the essay will begin with a discussion of some general, but important, questions Rosenthal fails to address. It will then turn to an examination of the two mental mechanisms Rosenthal invokes to explain conscious unity and it will argue that there are some kinds of conscious unity for which neither mechanism is able to account. The essay will conclude with a brief discussion about how Rosenthal's account of conscious unity presupposes the same kind of representational mismatches that some have argued pose a serious problem for higher-order theories of consciousness.The Unity of Consciousness and its Many FormsReflection on the nature and structure of conscious experience reveals that experience is unified in a number of different ways. Some forms of conscious unity apply to simultaneous (synclironic) conscious states. Others apply to states that are conscious at different times (diachronic). Perhaps the most fundamental kind of synclironic unity is phenomenal unity. A number of experiential states are phenomenally unified when they are experienced together as part of a single overarching or global experience at a time Tye (2003). My current experience, for example, is a complex one. I have a visual experience of my computer monitor. I hear music playing in the background. I can feel the chair pressing into my back and the keyboard beneath my fingers. I can taste the remnants of my last sip of coffee. Each of these experiences is independent of each other in the sense that it would be possible to have any one of them without the others. To use Nagel's (1974) well-known terminology, there is "something it is like" to see my computer monitor, and there is "something it is like" to hear music playing. But there is also "something it is like" to see my computer monitor while hearing music. The latter experience encompasses the former. When a number of experiences are encompassed by a larger experience in this way, they have a conjoint phenomenology. Theorists have used a variety of terminology to refer to this relation. Parfit (1984), Lockwood (1989), and Dainton (2000), for instance, say that such experiences are "co-conscious. …