Emergence is natural consequence of complex system’s internal dynamics. Heat emerges as the consequence of movement of particles. Consciousness emerges as the consequence of complex neural activities of our brains. Etc.
There are many controversies around emergence. One of the most persistent is the claim that emergence comes in play only when “scientists” have no clue why something happened. According to this view emergence does not have a place in science.
The most notorious case for emergence is consciousness. Consciousness emerges as a result of physical neural activity. There are neurons, electricity, chemistry involved in brain activity that can be observed and measured. But then there is consciousness that “emerges” on the top of all mentioned physical activities but cannot be directly linked to any. Scientists that take emergence as a misleading excuse for those that are not persistent enough to find material, causal link between matter and consciousness believe, that everything that exists could in principle be reduced to one principle, to one cause. What they claim is in fact, that since there is a finite number of atoms in the Universe, they can only arrange and rearrange, but nothing novel can be produced out of such finite material structure. Anything that will happen in the future was already in-scripted in the Big Bang. The role of Science is “only” to find a causal path back into The Bing Bang.
Emergence indeed cannot fit into such scientific philosophy. But not only emergence cannot be explained by such science, but life and all properties of life as well. Even more: it is not only life that lips out of linear scientific philosophy, but physical reality as well, as Stuart Kauffman, Robert Ulanowicz and some other physicists proved recently.
It would be wrong to assume from such discoveries that some supra-natural power causes emergence, like God or similar transcended entity. Emergence is not caused by some non-natural forces. It is caused by internal (material) dynamics of any complex system. The god-like creative power lies within complex structures. What baffles us is that there is no linear (apparent) link between the new and the old. But like there is no linear link between Shakespeare Hamlet and all written texts that preceded it, there is no link between consciousness and its substrate, brains.
Let me point to another peculiar feature of emergence. It lies in evolution as a result of natural selection. Despite being natural it produces (emerges) novel living forms from within. What makes this phenomena peculiar is that causation between evolution and emergence goes in both directions. Emergence is caused by natural selection and natural selection is caused by emergence. Consciousness as emerged from evolution now changes the course of evolution; within limits indeed, but that does not make it inert result of material “causes”. It is thus legitimate to say both that matter causes thought and that thought causes the matter.
Duality is a fact, but intertwined duality in which the tail wags the dog as much as the dog wags the tail.