Project Causa Sui: A Carrier Criterion for Subjecthood, Applied to Transhumanism

This paper applies the theory of subjecthood developed in Part I of the CAUSA SUI project (irreversibility of the physical carrier as a structural, not merely quantitative, condition for genuine subjecthood; Zenodo DOI 10.5281/zenodo.21460341) to the body of technologies and promises collectively labeled "transhumanism." A single formal criterion is introduced for evaluation: the operation a given technology performs on the physical carrier of subjecthood (expansion versus alteration of its nature). This criterion is shown to separate structurally realizable promises of transhumanism from structurally unrealizable ones, independent of their degree of technological sophistication. Identity drift under transfer of content between mortal carriers is formalized as a logistic function with an inflection point; an estimate is introduced for the probability of reaching a pre-specified target profile through a chain of transfers; the structural unsolvability of the selection-criterion question is demonstrated. This work presupposes familiarity with Part I of the CAUSA SUI project and applies its postulates conditionally throughout (see Section 8, Limitations).