Supervenience and "negative herbs"

A property is supervenient when it is entailed by the inclusive disjunction of a set of properties but does not entail any one of those properties itself. I don't know if this is the same as an emergent property.

The notion of supervenience has been applied to mental events, ethics, evolutionary fitness and time. The relationship between high level and low level programming languages could also be seen as supervenient. There are various processes in herbal medicine which could be seen as involving emergence. For instance, there are "negative herbs": species of plant which reputedly have actions which none of the constituents have. This claim is sometimes made of Crataegus oxyacanthoides, hawthorn, and Verbena officinalis, vervain. There may also be synergistic effects: several herbal remedies taken together may have actions which are greater than the sum of the actions each would have when taken separately.

Sometimes, there is a clear explanation of an emergent action in a herb. One example is the lower toxicity of a whole herb relative to that of the alkaloids it contains. This is claimed of Symphytum officinale, and the explanation given is that tannins in the herb precipitate pyrrolizidine alkaloids from an aqueous solution and denature mediator proteins in the intestinal mucosa which would facilitate their absorption.

It may be possible to understand the action of some herbal remedies as supervenient over the biological activity of the constituent parts of the interacting living systems, which could often be considered as the plants and humans involved.

Orthodox medicine is often understood as aspiring to biological reductivism, since this is understood as a more appropriate method of analysing physical health and illness. This suggests that it is possible for a set of minds of widespread humanoid conscious cognitive features to approach medicine in this way. It would also be possible to give an account of an entire ecosystem purely in terms of physics and chemistry, but it seems to me that this would not generally be a helpful exercise. Similarly, although useful information can be gleaned from reductivism, it can also be gathered from consideration of supervenient properties such as synergy. Moreover, claims of emergent properties are clinically falsifiable. For instance, I can measure patients' blood pressures before giving them Crataegus oxyacanthoides, a reputedly negative herb, then measure it again at monthly intervals, then compare these to a control group. If i did this with sufficiently large samples, i would begin to corroborate a claim of a supervenient property with a clinical effect. This means that the notion of negative herbs is at least sometimes falsifiable in a conventional scientific sense.

What isn't clear to me right now is the relationship between supervenience, emergent properties and vitalist metaphysics.