So, I am wondering if anyone could help me with the notions of grounding (supervenience?) and emergence in the modern discussions in philosophy of science. What are they and what is the relation between them? Any papers or simply thoughts?
Apparently, "grounding" is a new word of choice in metaphysical debates, there was a philosophical Conference on Grounding and Emergence held in Glasgow last May. This is a reaction to fading hopes of reducing sciences to more fundamental ones and ultimately to physics, which was the original programme of scientific realism, known as reductionism or physicalism. The original replacement was supervenience, changes in composite objects can not happen without changes in their physical substrates, but supervenience proved to be too weak and too vague a notion to satisfy many philosophers with realist leanings.
"Grounding" is an ostensibly stronger relation, which still falls short of a reduction. Since attempts to express it in terms of supervenience were unsuccessful Fine, Rosen and Schaffer recently proposed to treat it as a primitive instead. What "grounding" is supposed to express is that some states/processes "happen in virtue of" or "metaphysically depend on" others, and therefore are not "over and above" those others, which metaphysically "constitute" them. In application, grounding is supposed to complement statistical correlation and causal dependence as a mode of scientific explanation. Emergence is traditionally the opposite of reduction, higher level processes irreducible to lower level ones are called "emergent", grounding is consistent with epistemic emergence, emergence to us, true metaphysical emergence is excluded.
A paradigmatic example are mental states being "grounded" in the brain states. They are linked to them in a way different from a causal connection or outright reduction, but more definitive than mere supervenience or correlation. Fine in The Question of Realism traces the idea to Aristotle:"it is possible to imagine metaphysical scenarios in which the nonbasic, or grounded, is plausibly taken to be real. Suppose, to take one kind of case, that Aristotle is right about the nature of water and that it is both indefinitely divisible and water through-and-through". This is somewhat different from the use of "ground" as a source of justification by Kant, Hegel, Husserl or Heidegger, say knowledge is grounded in something (categories, pure intuition, being-here), but without being caused by it.
As Dupré in Metaphysical Disorder sarcastically remarked about supervenience, "if this dependency is not to be wholly mysterious, there is presumably some set of facts that could be known that would permit the inference of the macroscopic from a sufficient knowledge of the microscopic. Perhaps we could not, even in principle, know these facts. But God, I suppose, would need merely to exist in order to know them". Grounding is replacing this relation with essentially reduction, only we release ourselves from having to demonstrate it explicitly because it takes place metaphysically "in reality" rather than semantically "in theory". This has a ring of "advantages of theft over honest toil", in Russell's words. It remains to be seen if grounding can offer more than that.