The rule does not rule out epiphenomenalism. It only rules out entities without causal connection in any direction with the material world, and epiphenomenalism says that there is a connection, albeit only in one direction.
Epiphenomena can be considered in terms of causal graphs. Suppose you have two causal graphs proposed to describe some phenomenon. In one, there is a variable called X, with many arrows in and out. The second graph is identical to the first, except that X is renamed to a new variable Y, then X is added back in with a causal arrow from Y to X, and no other arrows impinging on X. Y is stipulated to be unobservable and un-intervenable on, and X to be observable but un-intervenable on in both graphs.
Given these limitations on observations and interventions, is there any experiment that can distinguish between the two graphs? I think there is not.
If not, what does it mean to say that there is such a Y, and that it is Y, not X, that is producing the apparent causal effects of X? It’s almost as if at the meta-level, it is Y, not X, that is the epiphenomenon.
The rule does not rule out epiphenomenalism. It only rules out entities without causal connection in any direction with the material world, and epiphenomenalism says that there is a connection, albeit only in one direction.
Epiphenomenalism is ruled out for other reasons.
Epiphenomena can be considered in terms of causal graphs. Suppose you have two causal graphs proposed to describe some phenomenon. In one, there is a variable called X, with many arrows in and out. The second graph is identical to the first, except that X is renamed to a new variable Y, then X is added back in with a causal arrow from Y to X, and no other arrows impinging on X. Y is stipulated to be unobservable and un-intervenable on, and X to be observable but un-intervenable on in both graphs.
Given these limitations on observations and interventions, is there any experiment that can distinguish between the two graphs? I think there is not.
If not, what does it mean to say that there is such a Y, and that it is Y, not X, that is producing the apparent causal effects of X? It’s almost as if at the meta-level, it is Y, not X, that is the epiphenomenon.