Anthony Trewavas will have ruffled a few green feathers in his Commentary “Urban myths of organic farming” (Nature 410, 409–410; 2001), in which he discusses the myths of organic agriculture. Many of the points he raises are valid, and will be accepted by many (though not all) adherents of organic farming.

Trewavas takes a highly positivistic attitude towards science, in contrast to most of the organic movement. In the positivistic world, something is true if established by the falsification of a null hypothesis. By contrast, many supporters of organic agriculture doubt that an objective, proven scientific truth can exist. They believe an agricultural system is more than the sum of its parts, that the reductionistic view widely used in natural science does not see the big picture, and hence that it fails as a political or social tool of analysis. Organic farming, of course, has a strong social and political agenda.

Take, for example, food quality. Trewavas states that “hundreds of rigorous tests have failed to reveal better-tasting properties or improved nutritional value, but have consistently shown that organic produce has lower nitrate and protein content”. The literature he cites, however, raises the point that a lot of food-quality studies concerning the impact of different growing methods lack standards for important parameters such as varieties, growing locations, maturity and storage conditions. These have important effects on compounds influencing the taste and nutritional value of fruit and vegetables.

In addition, only a few studies were performed for certain food groups, leaving the effects of organic or non-organic growing conditions unclear. Furthermore, people are not necessarily buying organic produce because they are unaware of any drawbacks. They may have other reasons which the researchers do not appreciate.

Because the positivistic point of view doubts what has not been 'proved', it will automatically be sceptical towards non-rigorous, anecdotal reported differences between organically and conventionally produced food. On the other hand, many supporters of organic agriculture rely on personal experiences and beliefs that make them more receptive to the idea that there is a difference between organic and conventionally produced food.

In essence, Trewavas is using organic agriculture as a case study of the tendency in modern western society for scepticism about science. Although, as scientists, we may deplore the fact that people are swayed by non-scientific views, the fact is that a lot of them are. Despite the arguments presented by Trewavas, many people believe that organic production systems produce better food, care more for animal welfare and are kinder to the environment. As inquisitive scientists, we should be asking why this is the case.

We should try not to see organic farming in “is it true?” black-and-white terms, but rather look at the social factors leading people to chose organic products. The role of science here is to assist social dialogue rather than simply to deliver the technical 'truth'. For instance, scientists could identify agricultural and environmental conditions under which organic farming might usefully be practised, and those in which it would not be beneficial.

In the era of BSE and of GM foods, we cannot escape the conclusion that the social position of science is changing. The crucial question is whether dialogue is possible between strict rationalists and those scientists more able to see their subject in a broad social context. That is the wider issue highlighted by Trewavas, and the one that needs to be considered by the whole scientific community.