|Dear Matthew, |
just a few clarifications concerning my lab's work. Note that I am just trying to catch up with the (main points of the) discussion, and I am probably missing many things. I look forward to seeing the discussion synthesised somewhere, in order to allow everybody to understand how we progress.
Matthew West writes (answering to Giancarlo Guizzardi):
MW: This is very similar to the 4D, but is relatively opaque, and gives more individuals than if you adopt extensional identity in 4D. In this case playing multiple roles simultaneously does not give multiple states, but one state playing multiple roles. A bit more elegant I think. MW: This seems to generalise the idea above a bit. One problem I have with both of these is that (if I understand it correctly) they treat social and other roles as purely classes. This gives me a problem if I want to shake the hand of the president, or start P101, because classes are abstract, and these are just things you can’t do to them. This is central to what I find unsatisfactory with these kinds of approaches. The situation is confused by there being several different meanings to role, from the participant role in an activity or state, to the component in a system, or social role with significant differences in character between them.
The second paper is still work in progress, while the first one is more established. In both cases, however, for sure the approach does not only admit roles as "pure classes", and new kinds of individuals are introduced. I defend a similar, although slightly different approach in the paper below, which explicitly considers the parts replacement problem (among other things) by introducing the notion of a "virtual individual" (NOTE - this is still a draft - comments welcome):