Joachim Krueger has a posting in the PsychologyToday blog (here). Where he attempts to use a logical construction to disprove the conclusions of DM Wegner (2002) The illusion of conscious will.
He summarizes Wegner’s conclusion as follows:
According to this (Wegner’s) view, the brain prepares and executes both action and the conscious intention of acting at the same time. Conscious will is thereby correlated action without having any causal power. The correlation is due to the common cause of brain activity. If conscious will does not (ever) cause action, it is a dead end in the stream of causation. Conscious will is, as it were, an organism without offspring in the great genealogical tree of nature. Just as future generations are begotten by other organisms that mate, future actions are caused by other brain activities that are not causally dependent on conscious will.
Krueger attempts to prove that this is illogical. The language is a bit messy here but the argument can be made clear. If a particular brain activity, and only that brain activity, causes both the ‘conscious will’ and the ‘action’, than if either the ‘action’ or the ‘conscious will’ do not happen, it follows that the brain activity did not happen. So either ‘action and ‘conscious will’ both happen or neither happens. Therefore either ‘conscious will’ is part of the casual chain or is epiphenomenal.
What do we make of this? First, the experimental evidence is that the action and conscious will do not always happen together, they can be separately under unusual circumstances. This little logical argument does not take this into consideration and therefore does not accurately describe the situation. It can be experimentally arranged to have ‘conscious will’ without ‘action’ and to have ‘action’ without ‘conscious will’.
Second, just because ‘conscious will’ is not in this particular casual chain does not mean that it is not in some other causal chain. (I would agree that it is fairly certain that consciousness has functions because it is too biologically costly to be a frill. In other words, it is extremely improbable that consciousness is epiphenomenal.) There are other brain activities: for example, the ‘conscious will’ feeling in consciousness may mark memories as being memories of intended actions as opposed to unintended actions. Such a marking would be causal in learning outcomes of actions etc. To learn from our actions we need to remember whether there was either or both a feeling of agency and a feeling of intent. Just because consciousness is not essential in causing intended actions does not make it useless or epiphenomenal, if it records the nature of the action.
One of the problems of logical arguments such as this one is that once ‘brain activity’ becomes B, ‘conscious will’ becomes C and ‘action’ becomes A, it is difficult to notice when the meaning of these terms subtly change. When a particular brain activity becomes any/all brain activity the logic evaporates. It is suddenly not the same B. One has to be careful at every step of the logic that there is not a sleight-of-hand with the meaning of the elements.