Before we discuss the self-as-subject in a more detailed manner, we focus on Liang’s conceptual refinements of the self-as-object. Liang proposes three important distinctions that are very helpful for the debate on bodily self-consciousness. The first marks out the fact of body ownership and the sense of body ownership. The fact of body ownership has nothing to do with phenomenal experiences of one’s own body. It just describes “[…] a biological fact about the anatomical structures of one’s body” (Liang this collection, p. 2). In contrast, the sense of body ownership describes the experiences of the factual aspect of body ownership. Hence, to experience something as belonging to one’s own body is to experience a biological fact. Then Liang distinguishes between the first-personal sense and the third-personal sense of body ownership. We think that this is a very explanatorily fruitful distinction. The first-personal sense of body ownership describes some pre-reflective states such as walking or proprioceptive states. But these states could be third-personal or reflective as well if there are experienced from the outside, for instance through mirror recognition of one’s own body parts.
The last distinction concerning the self-as-object is between the sense of body ownership and the sense of self as physical body. The sense of body ownership is the experience of various body parts belonging to one’s own body, while the sense of self as a physical body concerns more ontological questions of the self. Here Liang introduces the sense of self as physical body as the sense of being a person of flesh and blood.
Let us concentrate on the distinction between the first-personal sense and the third-personal sense of body ownership. For us it is a rich conceptual tool that can help us refine the classic Wittgensteinean distinction between self-as-object and self-as-subject. We suggest that the notions of the first-personal sense of body ownership and the sense of experiential ownership are often used interchangeably. There are closely related but of course distinct from each other. Imagine a person who recognises that her legs are crossed through the first-personal sense of body ownership. She experiences her legs to be her own crossed legs. But here the Wittgenstein question makes perfect sense. Is it really she who is experiencing that very state? This open question marks out the sense of experiential ownership. We share Liang’s criticism that the lack of a distinction between a sense of bodily ownership and a sense of experiential ownership could result in overinterpretation of some empirical data. If this distinction makes sense—as we think it does—then Liang’s claim that Damasio, Panksepp, and Northoff’s conceptions of the core self do not target the sense of self as experiential ownership sufficiently is plausible. The claims fit rather with the first-personal sense of body ownership.
In order to target the sense of experiential ownership, the Wittgenstein question could be asked to the participants of some experiments. Then we could, according to Liang, measure and elaborate on not only what is experienced but also on who is experiencing. Liang convinces us that there is more to explain than just senses of body ownership. If the sense of experiential ownership marks out a specific phenomenal target property, then much has to be done in philosophical and interdisciplinary empirical research. If Liang is right—which we think he is—and the target phenomenon of the sense of experiential ownership is empirically tractable, some further research would be very interesting and illuminating.