Conjoined Twins and the Biological Account of Personal Identity
Koch-Hershenov (Rose J.)
Source: The Monist, Vol. 89, No. 3, Coming into Being and Passing Away (July 2006), pp. 351-370
Paper - Abstract

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Author’s Abstract

  1. During the first 16 days after fertilization, the developing embryo1 has the capacity to separate into two genetically identical embryos2, or monozygotic twins3 (triplets, etc.). Because of this capacity, philosophers typically argue that the pre-16 day embryo4 is not a human being.
  2. On a Biological Account of Personal Identity (BAPI), which considers us human beings as essentially organisms, the development of the embryo5 into an organism at 16 (or 21) days marks our origins. The development of an embryo6 into an organism is also said to mark the point at which the embryo7 loses its potential to give rise to monozygotic twins8. This is considered a strength of the Biological account of our origins.
  3. I will argue here that it is the BAPI's own criteria that will have to allow cases of monozygotic twinning9 occurring even after 16 days, and that in virtue of this a Biological Account faces twinning10 puzzles usually reserved for earlier accounts of our origins.


Hard copy in "Various - Papers on Identity Boxes: Vol 08 (I-K)".

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