BTW, I'm currently reading _Objective Knowledge: an evolutationary approach_ (1972) by Karl Popper; and this type of issue is exactly what he addresses. Popper's section on the evolutation of knowledge in the third world (his term for a modified 'Platonic Realm') was strong, but lacked the precision that memetics inhereted from recent biological theories, especially a concept of a selfish replicator. On the other hand, he has very pleasing things to say about different forms of selection in the meme pool, and the results they can achieve.
Of course, before Joe explodes and says "that was my point!", I have to say -- yes! I agree that our knowledge of memetics has been helped immensly by our knowledge of biology. I just disagree that Darwin's theory emerged *because* of an 'empirical' study, or via some kind of 'induction' from the natural world: science just doesn't work that way, and memetics is only the latest example.
ERiC