Abstract
The central claim of the Parfitian psychological approach to personal identity is that the fact about personal identity is underpinned by a “non-branching” psychological continuity relation. Hence, for the advocates of the Parfitian view, it is important to understand what it is for a relation to take or not take a branching form. Nonetheless, very few attempts have been made in the literature of personal identity to define the “non-branching clause.” This paper undertakes this task. Drawing upon a recent debate between Anthony Brueckner and Harold Noonan on the issue, I present three candidates for the non-branching clause.
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Notes
According to Parfit, the right kind of cause may be (1) the normal cause (that requires the continued existence of the same brain), (2) any reliable cause, and (3) any cause (1984: 204-9). Parfit prefers the third view. Respecting Parfit, I will present my arguments from the perspective of the third view. However, similar arguments could easily be made mutatis mutandis in taking the other views as well.
Parfit says that there exist enough psychological connections when “the number of direct connections, over any day, is at least half the number that hold, over every day, in the lives of nearly every actual person” (1984: 206). I find this account unprincipled. For instance, it does not explain what counts as enough connections (for strong psychological connectedness) holding between two relata apart from each other by a time other than a day’s stretch of time. For our purposes, however, we may assume that there is a plausible criterion of counting enough number of psychological connections holding between two relata with any temporal distance. For further discussion, see Brueckner 1993: 2.
Parfit has not presented his view using the person-stage framework. However, with the conceptual maneuver that I will soon introduce, the kind of person-stage framework employed by Brueckner and Noonan can faithfully represent the core of the Parfitian view.
Here, (2) roughly means the following: There is a sequence of person-stages such that (a) the sequence starts with x, (b) it ends with y, and (c) each stage is C-related to its adjacent stage(s) in the sequence (i.e., each stage is C-related both to the immediately preceding stage in the sequence (if there is one) and to the immediately following stage in the sequence (if there is one)).
Though Parfit says that this is “the best description” of fission, his official view is that whether the pre-fission subject is identical to a post-fission offshoot is an empty question to which no determinate answer can be given. See his 1984: 254-60 and 1971: 4-10. It has been pointed out, however, that Parfit need not (and in my view, should not) appeal to this indeterminacy claim. Instead, he could have consistently argued that the pre-fission subject is determinately distinct from either of the offshoots, though “what matters” to the pre-fission subject is preserved in each offshoot. For further discussion, see Brueckner 1993: 8-9. I believe that such observation is tenable and that the advocates of the Parfitian view should not accept the indeterminacy claim. In order to make the Parfitian view as strong as possible, I will then ignore Parfit’s indeterminacy claim and assume that the Parfitian theorists would hold that the pre-fission subject and either of the offshoot are determinately non-identical.
Note that (5N) yields a desirable result that no one persists through the fission. The problem is that (5N) yields that no one persists before or after the fission. In other words, (5N) yields the problematic result that no one persists during any given amount of time in the Unbalanced Fission.
Here, (2) roughly means the following: There is a sequence of person-stages such that (a) the sequence starts with x, and (b) it ends with y, and (c) each stage (except y) is L-related to the next stage in that sequence.
But note that (5B) sustains the reflexivity of I at and after the fission. For instance, it ensures that CIC. The problem of (5B) is simply that it entails that no pre-fission stage bears I to any pre-fission stage (including itself).
Note that in considering whether CID, neither C nor D is C*-related to any of the stages in the right branch; hence, in (5C), (iiC) is true when x and y have the values C and D.
In fact, I have not here considered the following two possibilities: (IV) ∼(AIC), ∼(CID), and AID, and (V) ∼(AIC), ∼(CID), and ∼(AID). But, insofar as I can see, they only have the disadvantages of (I) and (III). So, I do not see any point in holding either of these views.
Here, I stipulate that if x and y are simultaneous, then either x or y can be the earliest of x and y. A similar remark applies to “the latest of x and y” in (a).
It seems clear to me that Parfit did not take the fusion case into consideration when he argued that copersonality consists in non-branching psychological continuity. However, for a complete analysis of the I-relation, I think it is relevant to discuss the fusion case as well.
Here I define: x is between y and z = df x is no later than the latest of y and z, and x is no earlier than the earliest of y and z.
References
Brueckner, A. (1993). “Parfit on What Matters in Survival,” Philosophical Studies 70, pp. 1-20.
Brueckner, A. (2005). “Branching in the Psychological Approach to Personal Identity,” Analysis 65, pp. 294-301.
Lewis, D. (1976). “Survival and Identity,” in A. Rorty (ed.) The Identities of Persons. Berkeley: University of California Press, pp. 17-40.
Noonan, H. W. (2003). Personal Identity. London: Routledge.
Noonan, H. W. (2006). “Non-Branching and Circularity – Reply to Brueckner,” Analysis 66, pp. 163-67.
Parfit, D. (1971). “Personal identity,” Philosophical Review 80, pp. 3-27.
Parfit, D. (1984). Reasons and Persons. Oxford: Clarendon Press.
Wiggins, D. (1980). Sameness and Substance. Oxford: Blackwell.
Acknowledgement
I would like to thank Anthony Brueckner and Luke Manning for helpful comments and discussions.
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Yi, H. Non-branching Clause. Int Ontology Metaphysics 11, 191–210 (2010). https://doi.org/10.1007/s12133-010-0068-9
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DOI: https://doi.org/10.1007/s12133-010-0068-9