If one believes that the brain is, in some as yet unspecified way, the organ of mind and behaviour, then all human behaviour has a neurobiological basis. Neuroscience research over the past several decades has provided more specific reasons for believing that many addictive phenomena have a neurobiological basis. The major psychoactive drugs of dependence have been shown to act on neurotransmitter systems in the brain (Nutt 1997; Koob 2000); common neurochemical mechanisms underlie many of the rewarding effects of these (...) drugs and the phenomena of tolerance and withdrawal symptoms (Hyman & Malenka 2001; Koob 2000), and there is evidence for a genetic vulnerability to addiction (Nestler 2001; Uhl 1999) that is mediated by genes that regulate the metabolism of psychoactive drugs and the brain neurotransmitter systems on which they act (Uhl 1999). (shrink)

Suppose there are two people having a moral disagreement about, say, abortion. They argue in a familiar way about whether fetuses have rights, whether a woman’s right to autonomy over her body overrides the fetus’s welfare, and so on. But then suppose one of the people says “Oh, it’s all just a matter of opinion; there’s no objective fact about whether fetuses have rights. When we say that something is morally forbidden, all we’re really doing is expressing our disapproval of (...) it.” The other person protests: “No!—that’s totally wrong. Of course there are objective moral truths.” And suppose their dispute now settles on this new matter of whether there are objective moral facts, and the debate continues. They’ve now stopped discussing abortion, and are discussing the nature of any moral debate about abortion; they’ve stopped doing ethics, and started doing metaethics. If wondering about what one morally ought to do is to engage in ethical thought, then wondering about what one is doing when one wonders about what one morally ought to do is to engage in metaethical thought. When we make public moral judgments are we stating facts, or are we just expressing our opinions? And if there are moral facts, then what kind of fact are they? Can moral judgments be true or false? Can moral judgments be justified, and if so how? These kinds of questions are the domain of metaethics. (I’m not saying that there is a crisp and principled line to be drawn between meta-ethics and regular ethical discourse; but it is, if nothing else, a pedagogically useful division of labor.). (shrink)

Various authors debate the question of whether neuroscience is relevant to criminal responsibility. However, a plethora of different techniques and technologies, each with their own abilities and drawbacks, lurks beneath the label “neuroscience”; and in criminal law responsibility is not a single, unitary and generic concept, but it is rather a syndrome of at least six different concepts. Consequently, there are at least six different responsibility questions that the criminal law asks – at least one for each responsibility concept – (...) and, I will suggest, a multitude of ways in which the techniques and technologies that comprise neuroscience might help us to address those diverse questions. In a way, on my account neuroscience is relevant to criminal responsibility in many ways, but I hesitate to state my position like this because doing so obscures two points which I would rather highlight: one, neither neuroscience nor criminal responsibility are as unified as that; and two, the criminal law asks many different responsibility questions and not just one generic question. (shrink)