"Sports doping"--the use of anabolic steroids and other drugs to increase athletic performance, as Barry Bonds, Roger Clemens, and other prominent professional athletes have been accused of doing--is intensely controversial. A recent article in Nature--Barbara Sahakian and Sharon Morein-Zamir, "Professor‚Äôs Little Helper," Dec. 2007--discusses the parallel phenomenon of "intelligence doping." The term refers to the use of drugs to enhance cognitive performance. These are drugs like Adderall, Modafinil, and Provigil that are used to treat genuine disorders, such as attention deficit disorder in the case of the former and narcolepsy in the case of the latter. But they can also be used by normal people, including students and academics, to improve cognitive functioning by increasing concentration, memory, wakefulness, and mental energy generally. Coffee has many of the same effects, but they are much weaker. As in the case of sports doping, there is concern that the use of these drugs may have long-term adverse effects on the health of the user. There is even less evidence of this in the case of sports doping, however. But this may be because these drugs are newer--which means that they are just the first wave of cognition-enhancing drugs and that the subsequent waves will be more effective. Becker and I blogged about sports doping on August 27, 2006. We pointed to the arms-race character of the practice. Because of the importance attached to winning an athletic event, anything that increases an athlete's performance, such as taking steroids, places pressure on other athletes to do likewise. The result is expense, and also possible ill health, without any certain improvement in the quality of athletic competition as perceived by fans. That is not necessarily a compelling argument for trying to ban sports doping; indeed I consider the argument weak because of the difficulty and hence cost of monitoring drug use, especially the newer enhancement practice of "gene doping," and because of the existence of borderline enhancement practices (borderline between "natural" and "artificial"), such as training at a high altitude in order to increase one's production of red blood cells, which in turn enables a greater absorption of oxygen, or undergoing eye surgery to increase visual acuity. If fans object for whatever reason to sports doping, then sports leagues and team owners will have an incentive to ban the practice; the argument for criminalizing the practice would then depend on whether purely private sanctions could achieve an adequate level of deterrence. Suppose teams, leagues, and players all want to ban sports doping whether because of health concerns or fans' preferences, but that detection is extremely difficult, so that the probability of catching an athlete doing sports doping is very low. Then the optimal punishment may be more severe than the team or league could impose. The argument is the same as for why embezzlement is a crime, rather than the government's leaving it to the bank to punish the embezzler by firing him or suing him for the money he stole. Fans appear to be ambivalent about banning sports doping, because they are concerned with absolute rather than just relative performance, and so enjoy the additional spectacle created by "bionic" athletes. In fact neither the teams (and leagues) nor the players' unions seem enthusiastic about banning the practice, which suggests that it does not decrease--it may actually increase--the incomes of the teams and (on average) the players. The case for banning intelligence doping is even weaker than the case for banning sports doping. One reason is that there is a strong positive externality from increased cognitive functioning, since smart people usually cannot capture the entire social product of their work in the form of a higher income. Like other producers, part of the benefit that their production occurs inures to consumers as consumer surplus. An example is patentable inventions. Because patents are limited in duration, usually to 20 years, any benefits that a patented invention generates after the patent expires enures to persons other than the patentee. Even if there were no positive externality--even if the user of an intelligence-enhancing drug captured the entire incremental income generated by that use--there would be a social benefit, since the user is part of society, and hence no economic argument for banning. What is a possible source of concern is that because there is competition based on intelligence, for example to get into good schools or win academic prizes or achieve success in commercial fields such as finance that place a premium on intellectual acuity, the availability of intelligence-enhancing drugs places pressure on persons who would prefer not to use them because of concerns over their possible negative health consequences to use them anyway. There is also a danger that such drugs produce only very short-term effects, for example on exam performance, that may exaggerate a person‚Äôs long-term ability. (This is one of the reasons for objecting to exam coaching.) But against this is the fact that it is even more difficult than in the case of sports doping to draw a line between permitted and forbidden uses of cognition-enhancing drugs. It is hard to define "normal" cognitive functioning in a meaningful sense. Should people with an IQ above 100, which is the average IQ, be forbidden to use such drugs, but people below that level permitted to use them until it brings them up to 100? That would be absurd. The person with an IQ of 120 would argue compellingly that he should be allowed to take intelligence-enhancing drugs in order to be able to compete for good school placements and jobs with people having an IQ of 130. And so on up. Of course the naturally gifted will object to any "artificial" enhancements that enable others to compete with them. But it is not obvious why their objections should be given weight from a public policy standpoint. It is not as if allowing such enhancements would be likely to discourage the naturally gifted from developing and using their gifts (it might have the opposite effect, by creating greater competition for them), let alone discouraging bright people from seeking out other people to marry and produce children by.