De servo arbitrio, that is: will the neurosciences free us from the burden of freedom?

Abstract

According to some neuroscientists – called hard or radical determinists – philosophical, ethical and juridical consequences, in particular deterministic consequences, can be drawn from neurobiological researches. The subject of this work is thus the question whether the discovery of the cerebral  mechanisms correlating  with  our choices and decisions will eventually  sweep off our firm long lasting belief in human freedom. Among those who consider  the freedom of man an out-of-date idea, and just when crime is in question, we come across Greene and Cohen: in their opinion  crimes should be imputed to our brain and we would then be innocent. They have apparently chosen the reductionistic option, which regards the mind as a secondary phenomenon of the brain; but we can object that we are not “only” our brain. Libet and coll. would have supported the idea that conscious acting is but illusory, proving through experiments that the neurological impulses causing the actions that seem to us voluntary, can actually be traced about 200 thousandths of a second before the subject perceives his conscious decision. However this can at most prove that we become conscious of our choice only after  making it in case of  almost automatic or scarcely  significant or  impulsive actions, which bypass our conscious will. Otherwise our actions start before we become aware  of them  when we are beyond pathological limits. We should also keep in mind that we are actually speaking of  laboratory experiments, in which only simple and scarcely significant actions are asked of the subjects, that is actions little involving the subjects’ values and beliefs. Whatever we do obviously requires a biological frame. However all this proves that a  neuronal substratum is a condition necessary to our actions and our decisions – which philosophy calls condicio sine qua non – but  cannot be regarded also as a sufficient condition. Besides: does the fact that cerebral and mental events relate with one another mean that the former must necessarily cause the latter? Why couldn’t it be just the opposite? That is, above all: correlation is not causation. Greene and all those who reduce a moral choice to a mere question of this or that portion of the brain seem to overlook a further distinction, that is the one between facts and values: a descriptive statement cannot be changed into a set of norms and values (prescriptions). We must also remember  that a crime is acknowledged as such on not natural but cultural grounds. It is only obvious that when we make a choice actually some portions of the brain are activated, and  also  different portions of it may be activated whether our choice is “right” or “wrong”, that is whether it is in agreement or in contrast with what has been stored up within ourselves through man evolution. But this concerns the structure of the choosing process, not its various kinds of content. According to Greene  and Cohen our “belief” in will-freedom would be determined by the structure of our brain and would thus be but an illusion, and what’s more, a biologically induced illusion. Well, some objections can be raised to such assertions both from a skeptical and a methodological point of view, like: just on the contrary the determinism itself might be “written in our brain”. Besides, the assertion of the determinists is anything but scientific because as it is it cannot be confuted. When research is concerned, neurosciences, like all sciences, obviously use  models, in particular reductive models; but models as such neither are the reality nor include the whole, therefore they cannot exclude the existence of what is not relevant to their purposes. If our being is not only our brain but also our history, then we cannot speak of an absolute freedom, uprooted from our experience and from the factors actually influencing us, among which the biological ones. Moreover, all the factors conditioning us are actually “conditions” not “causes”, that is they reduce the number of our possibilities, but – except for some extreme cases – they don’t necessarily cancel such possibilities. From a logical point of view, though, it is not impossible to assert that a cause makes the occurrence of an effect more probable without making it necessary, which means events can be caused and not determined. Finally we mustn’t forget the “double nature” of human beings: in fact they share the causal structure of the physical world and are nevertheless free-acting beings causing their own actions as capable of self-determination and endowed with the possibility of acting otherwise.