Personality Change and the Problematic
From my perspective, of course, change in personhood is change in a qualitative whole. Suppose, for instance, we have a complete set of paintings from a great artist, arranged chronologically from youth to old age. As we scan the series, we might intuitively grasp the way the artist developed, note periods of either stability or considerable change. Like an art scholar, a personologist might have portraits of a person over time, perhaps with a running commentary on life as it was lived. And like an art scholar, a personologist would want to describe the nature of the change, what it means, what principles seem to make sense of it, and the like. To do so, to do justice to these qualitative wholes that merge and diverge, one must try to remain faithful to these wholes.
Some aspects of change can be quantified, but nearly always the result is misleading. Note that I am not claiming quantification is somehow bad. This would be absurd, particularly since some aspects of qualitative description are quantitative, such as "more or less." Rather, unbridled quantification is destructive in its use. Variables are often artificially abstracted simply because they can be measured. Qualitatively, significance guides attention and stems from a prior understanding or appreciation of a whole. The selection of quantifiable variables tends typically to be indifferent to the whole, employing instead a metaphysics that counts as real only what can be measured, or worse, employing numbers as a mere convention of what real scientists are supposed to do. Such procedures select with little regard for significance and