Alfred Mele
In Free Will, Causality, & Neuroscience
Chapter 4
Here are some excerpts:
Decisions to do things, as I conceive of them, are momentary actions of forming an intention to do them. For example, to decide to flex my right wrist now is to perform a (nonovert) action of forming an intention to flex it now (Mele 2003, ch. 9). I believe that Libet understands decisions in the same way. Some of our decisions and intentions are for the nonimmediate future and others are not. I have an intention today to fly to Brussels three days from now, and I have an intention now to click my “save” button now. The former intention is aimed at action three days in the future. The latter intention is about what to do now. I call intentions of these kinds, respectively, distal and proximal intentions (Mele 1992, pp. 143–44, 158, 2009, p. 10), and I make the same distinction in the sphere of decisions to act. Libet studies proximal intentions (or decisions or urges) in particular.
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Especially in the case of the study now under discussion, readers unfamiliar with Libet-style experiments may benefit from a short description of my own experience as a participant in such an experiment (see Mele 2009, pp. 34–36). I had just three things to do: watch a Libet clock with a view to keeping track of when I first became aware of something like a proximal urge, decision, or intention to flex; flex whenever I felt like it (many times over the course of the experiment); and report, after each flex, where I believed the hand was on the clock at the moment of first awareness. (I reported this belief by moving a cursor to a point on the clock. The clock was very fast; it made a complete revolution in about 2.5 seconds.) Because I did not experience any proximal urges, decisions, or intentions to flex, I hit on the strategy of saying “now!” silently to myself just before beginning to flex. This is the mental event that I tried to keep track of with the assistance of the clock. I thought of the “now!” as shorthand for the imperative “flex now!” – something that may be understood as an expression of a proximal decision to flex.
Why did I say “now!” exactly when I did? On any given trial, I had before me a string of equally good moments for a “now!” – saying, and I arbitrarily picked one of the moments. 3 But what led me to pick the moment I picked? The answer offered by Schurger et al. is that random noise crossed a decision threshold then. And they locate the time of the crossing very close to the onset of muscle activity – about 100 ms before it (pp. E2909, E2912). They write: “The reason we do not experience the urge to move as having happened earlier than about 200 ms before movement onset [referring to Libet’s partipants’ reported W time] is simply because, at that time, the neural decision to move (crossing the decision threshold) has not yet been made” (E2910). If they are right, this is very bad news for Libet. His claim is that, in his experiments, decisions are made well before the average reported W time: −200 ms. (In a Libet-style experiment conducted by Schurger et al., average reported W time is −150 ms [p. E2905].) As I noted, if relevant proximal decisions are not made before W, Libet’s argument for the claim that they are made unconsciously fails.
