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Once upon a time, and it wasn't so long ago, there was nothing round here but fundamentalists. Any public pronouncement on drugs had to be accompanied by due expressions of concern, and preferably condemnation. There was just one thing that really needed to be said about drugs, and that was "no".

Today, the Just Say No principle endures but its adherents have lost their nerve. They still believe in it as an ideal, and much of public opinion may well agree with them, but they know that it doesn't work as a policy. And they have nothing else to say; so the space has been filled by innumerable opinion pieces, editorials and books advocating various degrees of change to the regime by which intoxicants are controlled.

Standing out in this crowd is not easy, but Stuart Walton has achieved it with his sophisticated pro-drug fundamentalism. It's a little while before the nature of his book becomes clear. Early on he seems to be promising a scholarly overview of drug history, and a sociological survey based on "respondents". But these characters slip in and out of the rhetorical shadows, fading as Walton warms to his argument. He applies his literary craft and his learning, both of them impressive, to the thesis that the human condition is an intoxicated condition. To the current prohibition regime and its "No" slogan he gives the retort that it had coming to it: intoxication, he proposes, is a human right. And then some: it is "our birthright, our inheritance and our saving grace".

True to its theme, Walton's compelling and trenchant polemic is apt to induce a welter of sensations. The rush is exhilarating, but may be accompanied by queasiness. Walton's sentences are a pleasure to contemplate, as is the extent of his frame of reference, from classical Athens to Janis Joplin.

Almost all readers will find plenty here they didn't know before. But his rhetorical stance allows him to disregard questions which many readers would consider essential. He is happy to observe that illegal drug use seems to be increasing relentlessly, for he sees this "mass defiance" as a "heartening and positive phenomenon".

It is thus easy for him to acknowledge that legalising drugs would lead to further increases in their consumption. He sees no need to discuss the possible health consequences in any detail. Similarly, he is scornful of unit-counting, a suspiciously elastic set of goalposts erected to inhibit alcohol consumption, but the actual evidence about health risks is beside his point. His is a reactionary stance in the strict sense of the term, and occasionally it leads him to sound reactionary in the familiar sense.

Giving alcohol to children has "sound historical precedent", he claims, noting that boys of 10 used to be given strong ale for breakfast. They also used to be soundly thrashed, and that supposedly never did them any harm either.

Walton relies heavily on nature to underpin his case for the fundamental significance of intoxication, arguing that it is probably an instinct because it is universal. That would not in itself make it our "organic birthright", since you could say the same about homicide. And since the illicit drug market stands about as much chance as homicide of being legalised in the politically foreseeable future, discussions about drugs are likely to drift into such airily speculative regions. They may as well take the opportunity to wander where they will, free from any pressing obligation to think through policy. Instead of just saying no, people can now say just what they please, to just as little effect.

Marek Kohn's Dope Girls: The Birth of the British Drug Underground is published by Granta.