I have often tried to explain my biggest problem with connectivism (most recently on Friday). Maybe a picture works better.
See Slideshare version
There is the neuronal layer (more precisely: “domain”), and then there is the society layer. But how are these related? The recent criticisms show that it is difficult to reconcile these two. Unfortunately, a possible third one closing the gap, does not yet qualify for the strictly sound arguments of Stephen Downes: the conceptual connections, that are still merely a metaphor.
However, I think they make it easier to understand what “knowledge in a society” means.