Of all the arguments levelled against taking drugs for human enhancement, the idea that it is cheating has least power. Yes, when organized competition or formal testing of abilities is the name of the game, drug-based strengthening is questionable and regulations against it need to be adhered to.

More debatable are arguments by opponents of drug-based enhancement that it is cheating against oneself. “Personal achievements impersonally achieved are not truly the achievements of persons,” said the report Beyond Therapy by the US President's Council on Bioethics, chaired at the time by ethicist Leon Kass. Yet imagine if a researcher could improve his or her ability to memorize the postulated connections in a complex signalling pathway central to tumour development, or if a musician could improve his or her concentration and deliver a better performance on the night. Far from cheating on themselves or others, they would be delivering a higher return on their investment of effort, and indeed on society's investment in them. We all benefit.

Studies have documented usage of drugs for cognitive enhancement by 5–15% of students.

What is sure is that opponents of enhancement are, to a degree, whistling in the wind. They raise other spectres — unfairness of access (although today's enhancing dose is cheaper than a cup of coffee), possibilities of employer coercion and the loss of human dignity or of the 'natural' — but ultimately, to little avail. Many healthy people still opt for chemical enhancements of all sorts, as suppliers of cosmetics and some pharmaceuticals know well. Such actions betoken an ethical argument on the other side: the pursuit of personal liberty.

Studies on healthy volunteers have shown the cognitive effects of enhancing drugs to be mild, but sufficient to be considered helpful. The pills with least risky side effects seem to be methylphenidate (prescribed for attention-deficit disorder) and modafinil (prescribed for narcolepsy). Studies, mostly in the United States, have documented usage of drugs for cognitive enhancement by 5–15% of students, and anecdotes abound of use by postdocs and academics.

As described in a valuable discussion paper from the British Medical Association (http://www.bma.org.uk/ap.nsf/Content/CognitiveEnhancement2007), these drugs have an honourable track record in helping the afflicted — and they could do yet more to that end. The risks of long-term use are not well understood (although that also applies to many approved drug therapies). And the ethical issues are not to be ignored, although the document lacks a description of who stands to make money from enhancement drugs. Appropriately, it reviews the issues and sets out topics for debate, rather than advocating use or restriction of enhancers.

The debate itself is not new, but it has been confined to relatively small circles. Yet the use of cognitive-enhancing drugs by both the ill and the healthy — and those in the substantial grey zone overlapping both — is already more widespread than is generally appreciated. The lack of debate on regulation by nations or by institutions, such as universities, is increasingly problematic. And those in favour of chemically induced cognitive enhancement for the healthy need to develop their scientific and ethical case, because it will be all too easy for the ethically conservative to hold sway over political leaders, most of whom would prefer to wish this particular challenge away.