Though, arguably, if one is a true Platonist, one should view roles
as Aristotelian, and base classes as Platonic and therefore more
"real"...but I'm more of an Aristotelian myself, so I tend to think
of the Platonic ideals as less real than reality.
Whatever. Both Plato and Aristotle would probably have hated our
modern conceptions of what they thought. But I suspect Plato would
have liked Smalltalk or ML, while Aristotle would doubtless be
programming in something like Self, or maybe C...