Is science harmed by the reckless use of ... metaphors?

Carl Philips, Brian Guenzel and Paul Bergen are hopping mad about bad metaphors. Writing in the Journal of Harm Reduction, they pull on their imaginary boxing gloves.

Stepping into the ring, so to speak, they declare: "Anti-harm-reduction advocates sometimes resort to pseudo-analogies to ridicule harm reduction. Those opposed to the use of smokeless tobacco as an alternative to smoking sometimes suggest that the substitution would be like jumping from a three-storey building rather than a 10-storey, or like shooting yourself in the foot rather than the head."

Following their summary of these two disagreeable analogies, Philips, Guenzel and Bergen proceed to administer a good thrashing.

They have collected several versions of the "jump from a building" metaphor. While some metaphor makers "likened smoking to falls from at least the 10th floor and smokeless tobacco to falls from at least the third, we found numbers as high as 50 and 30".

These are beneath contempt, they explain, because "anyone with a passing familiarity with the human body and earth's gravity should be aware that falls from the 10th storey are almost always fatal".

Perhaps unsure of their own familiarity with the human body and Earth's gravity, they conduct a review of the available literature on mortality rates as a function of free-fall distance.

"It is surprising," they write, "how little information is published on the topic. The literature suggests that falls from up to the third storey are almost always survived, with the death rate increasing sharply and approaching 100% over the next three or four storeys.

"More accurate analogies might actually be fairly useful in painting the picture for consumers. A non-trivial portion of young men have probably jumped from a second-storey window, but few would dare jump from the fourth."

This is their main line of attack, and they go at it from other directions, too.

In the second bout, they pummel the "gunshot to the head" metaphor, applying a devastating one-two punch combination:

· "It is immediately obvious that the gunshot metaphor is absurd: if someone was faced with the choice of shooting himself in the head and shooting himself in the foot or leg, the latter option is quite obviously better from a health-outcomes perspective."

· "Mortality risk from self-inflicted gunshot wounds to the head dwarfs that from smoking, while foot wounds, though they have a low mortality rate, have a high probability of permanent debilitating orthopedic damage, a risk absent in tobacco use."

In the end, they let slip what has most got up their nose. "The metaphors," they write, "exhibit a flippant tone that seems inappropriate for a serious discussion of health science."

Philips and Bergen are at the University of Alberta in Edmonton. Guenzel is at the centre for philosophy, health and policy sciences in Houston, Texas.

· Marc Abrahams is editor of the bimonthly magazine Annals of Improbable Research and organiser of the Ig Nobel Prize