Is free will an illusion?
Maxine Clarke
Wednesday, 03 June 2009 10:04 UTC
Scientists and philosophers are using new discoveries in neuroscience to question the idea of free will. They are misguided, says Martin Heisenberg, professor emeritus in the department of biology at the University of Würzburg, in a Nature Essay (Nature 459, 164-165; 14 May 2009). “At the scale of planets, quantum effects give way to the deterministic laws of classical mechanics. At an intermediate scale, however, they are occasionally amplified to become observable, for example when we measure radioactive decay. In general, life is an interplay between the deterministic and the random. There is plenty of evidence of chance at work in the brain: take the random opening and closing of ion channels in the neuronal membrane, or the miniature potentials of randomly discharging synaptic vesicles. Behaviour that is triggered by random events in the brain can be said to be truly ‘active’ — in other words, it has the quality of a beginning.”
There is plenty of evidence, Professor Heisenberg writes, that an animal’s behaviour cannot be reduced to responses. Fruit flies, for example, can modify their expectations about the consequences of their actions when in situations they have never encountered. They can solve problems that no individual fly in the evolutionary history of the species has solved before. They can be made to use several different motor outputs to escape a life-threatening danger or to visually stabilize their orientation in space. Thus, according to Professor Heisenberg, self-initiated action is not in conflict with physics and can be demonstrated in animals. Humans can be considered free in their behaviour, in as much as their behaviour is self-initiated and adaptive. We need not be conscious of our decision-making to be free. What matters is that our actions are self-generated. Conscious awareness may help improve our behaviour, but it does not necessarily do so and is not essential. Why should an action become free from one moment to the next simply because we reflect upon it?
Updated 03 June 2009 10:13 UTC
-
Replies
Jump to resultsResults
-
Sorry to enter this debate.
Determinism is not dead. Heisenberg never said that it was. What is dead is mechanicism, i.e. the idea that knowing a given state of a system it is generally possible to predict its outcome in the long term. In short predictability is not the same thing as determinism. I do not say that because we do not know the initial conditions. No. This is true even in arithmetics, knowing all initial conditions. Let us – at least for the time being – ask what is the nth digit of pi, with n large. The only way to know this (once again, at least for the time being) is to compute the digits… The reason for that is coding and recursivity (see e.g. Gödel, Escher, Bach by Douglas Hofstadter for a long demonstration).
This is the basis of the concept of logical depth, proposed in 1988 by Charles Bennett. And if one accepts the idea that cells could be computers making computers (Turing Machines making Turing Machines) then this has the remarkable consequence that because DNA comes from DNA, comes from DNA etc, there is no “junk” DNA: every single nucleotide being logically deep.
There is a lively discussion on these matters in synthetic biology at the present time…
-
In his Essay ‘Is free will an illusion?’ (Nature 459, 164–165; 2009), Martin Heisenberg suggests that belief in free will is supported by quantum events. He makes the distinction between “conscious” free will and another type of free will, described by “self-generated actions”. Subsequent letters have refined his initial points by including discussion of emotions and conscious contributions to our physiochemical state and recognizing the biological inheritance of these states.
These points are well-taken with respect to the scientific literature, indeed what we describe as “consciousness” may be present in some ways within animals and insects previously thought to be unconscious or even having their actions completely determined by external stimuli. However, taking action that is not determined by external stimuli does not an expression of free will make. I suggest that this discussion of a new type of “free will” is not a discussion of free will at all, and that conscious free will is the only sense in which “will” has the meaning of philosophical significance.
This is based on his reference to “self-generated actions” as the defining evidence for free will, rather than the ability to consciously alter one’s action. I humbly suggest that, for “self-generated actions” to have the meaning of “will” that is commonly discussed in philosophy, the “self” in question must be the self of Descartes (“I think therefore I am” as the definition for a conscious “self”).
Heisenberg’s suggestion that the subconscious self is also capable of “free will” because it can self-generate events is misguided in that it allows for “random will” to be considered a type of free will. He points out “that behavioural output can be independent of sensory input.” However, he then uses an example of output resulting from “the interplay of chance and lawfulness in the brain”. This argument suggests microscopic chance can be considered evidence of free will. I would argue it shows only that this type of self-generated event is an example of “random will”, not free will in any sense that is philosophically meaningful.
Further, one should be careful in suggesting that, because “their brains, in a kind of random walk, continuously pre-activate, discard and reconfigure options, and evaluate short and long-term consequences” bacteria have free will. From my field, that interpretation would consider my computer to have free will, because I can program it to do Monte Carlo Molecular Dynamics (a real type of random walk, where the rules for discarding, reconfiguring, and evaluating are pre-determined).
As to the question of determinism or free will, it clearly remains unanswered. Rather than complicate matters with a new definition of “free will”, I suggest incorporating “random will” into the existing philosophical framework, as per Heisenberg’s examples. I welcome an experimental indication that humans do in fact have a philosophically meaningful free will, but, in lieu of that, I’ll have to settle for a simple indulgence of my own sense of free will by ending this correspondence unexpe
Results
-
