The presidential address of G. C. Varley to the British Ecological Society in 1957 was entitled “Ecology as an Experimental Science.” Though delivered in January, it was published in November and thus was not known to me in June, when I made a plea for ecological field experiments at the Cold Spring Harbor Symposium on Quantitative Biology. It is an irony of history that Hutchinson's “Concluding Remarks” at the symposium set off an extremely popular movement in ecology that was almost the antithesis of experimentation. Despite the widely acclaimed experiments of Connell and Paine, the method attracted few practitioners for at least fifteen years, while the ecological world stood bemused by mathematical theory as a way of explaining observations made in the field. The wave of enthusiasm was most pronounced in the United States, but it affected, and still affects, ecologists in all parts of the world, as a perusal of the journals will show.

Some of the observations did not confirm the theories, but were nevertheless claimed to do so (Roth 1981; Simberloff & Boecklen 1981). During that period, few authors considered alternative explanations for their observations, and in addition there was the danger that the confirmatory evidence was known in advance of the construction of theory. Such a sequence involves circularity, with its obvious flaws as a method of scientific procedure. Explaining data, whether verbally or through mathematics, is a legitimate method of stating hypotheses, but they remain just that until put to an a priori test.