Carington's theory is compatible with interpreting psi-phenomena in terms of either causal or cognitive relations on the lines described earlier. It suggests however a possibility not previously mentioned, namely that some of the constituents of different minds are not merely alike, but are numerically identical. This notion provides one, possibly intelligible, answer to the question -- how can your associating K and O tend to make me think of O when I think of K? This is one way of interpreting "common unconscious," and it has been entertained by some psychical researchers. I feel strongly inclined to dismiss this notion as nonsensical; but I do not think we are entitled to do this merely because our verbal conventions debar us from speaking of "two minds owning the same experience." (We may in any case be forced to revise this convention, if, as Russell has suggested, physiologists learn to make a nerve connecting my brain to your aching tooth.) I mention this notion to illustrate how psychical researchers are driven to entertain possibilities which are so shocking to common-sense that many people conclude that they belong to the lunatic fringe. I feel confident that philosophers will not subscribe to this verdict, if they attend to the facts which psychical researchers are trying to explain and to the scientific postulates which seem to be violated.
Regarding the question which is the subject of this symposium, I must leave it to you to decide whether the discussion of the issues I have raised is a proper and important task for philosophers. We could leave such tasks to be performed by scientists, but, whether or not science would suffer, philosophy would surely lose by this policy.