The New York Times blog featured a debate recently, in the wake of the Tuscon massacre, among several people on the insanity defense. One of the debaters, Kent Scheidegger, wrote a comment that included a point that's often proposed but that needs some amendment.
Scheidegger said "The traditional test [of criminal responsibility] is whether the defendant was able to understand the nature of the act and understand that it was wrong. This test … remains the proper legal and moral test. A person who understands what he is doing and that it is wrong but does it anyway is morally responsible for his act."
There's a problem with this idea, namely, that at times culprits place themselves into a position of being unable "to understand that nature of the act and understand that is was wrong," as when they voluntarily become severely intoxicated by drugs or alcohol or some other behavior that leads to mental incapacitation. So strictly speaking while the crime is being committed, the understanding Scheidegger says is required for culpability is indeed missing; so by his account perpetrators cannot be held criminally or even morally responsible for what they have done. Yet, arguably, such persons would still be fully responsible since they ought to have been sufficiently prudent or careful prior to becoming unable to understand and embarking on conduct that requires care.
Thus, if one sits at home alone (or with family likely to offer care if needed), and imbibes to a point of mental incapacitation, that's one thing; but if one does so just before undertaking tasks where the effects of alcohol or drug consumption can reasonably be expected to lead to a crime, that's another. Ignorance of those effects at the time of the commission of the crime should be no excuse – one ought to have known!
Of course these days there are innumerable reasons being offered for not holding anyone responsible for anything one does, be it criminal or noble or whatever. The most influential grounds for this come from some experiments conducted recently in which it has been determined that an agent of conduct is most often motivated un- or subconsciously. Reported cat scans of the human brain have shown that prior one's conscious awareness of what one is intending to do, the action in question has already commenced in the brain, with consciousness coming only later. So what one is doing is in fact not in one's conscious control. Such experiments were conducted by, among others, the famous neuro-scientist Benjamin Libet. Libet himself, while casting doubt on consciously willful conduct concludes one of his famous essays, "Do We Have Free Will?" – included in Benjamin Libert, et al., eds., The Volitional Brain, Towards a neuroscience of free will (Imprint Academic, 1999) – with the observation that free will's "existence is at least as good, if not a better, scientific option than is its denial by determinist theory." Yet he regards the hypothesis of free will's existence "speculative," but does the same with the determinist position. As he puts it, "Given the speculative nature of both determinist and non-determinist theories, why not adopt the view that we do have free will (until some real contradictory evidence may appear, if it ever does)."
Since the time Libet carried out his studies there has been considerable work on the issues involved in the free will and conscious willing controversies (work that's continuing as I write these lines – for example, at the recently established Santa Barbara Institute for Consciousness Studies at UC Santa Barbara, which, as its web site states, "is dedicated to interdisciplinary research and education to advance understanding of the nature and potential of consciousness." Libet's earlier work has sparked much further work and debate but a good many neuroscientists contend now that it and further work has indeed lead to the conclusion that conscious willing is not very likely – see, for example, Daniel M. Wegner, The Illusion of Conscious Will (MIT Press, 2002).
I am not going to be able to chime in very fruitfully on this topic in a short column but I do wish to call attention, briefly, to a line of argument favoring freedom of the will that seems not to be addressed much these days when only experimental science is trusted to handle the issues involved. This line of argument basically holds that the existence of free will is undeniable or on strictly conceptual or logical grounds – that is, axiomatic – since scientific knowledge itself depends on it.
Basically the point is that knowledge must involve independent, unprejudiced observation and thinking but determinism denies this since it holds that everything one does is controlled by various impersonal causes impinging on one's conduct, including one's observations and thinking. If that were so, then no conclusion about anything, including about the free will issue, could be considered sound since all of it would be simply imposed on us. We would not in fact be concluding from unprejudiced reasoning and observation but merely exhibiting behavior imposed on our brains and caused by such imposition.
So it is best to conclude that if science is possible, including about the human mind, free will must exist.