Introduction

Much of ecology consists in making observations and then devising plausible explanations for the observations. Because alternative explanations of the observed phenomena frequently are available, the process by which the conclusions have been reached is known as “weak inference.” It is not that the conclusions are necessarily wrong; the problem is that there is little assurance that they are right, and the widespread use of the approach has led to severe criticism, from both outside and inside the field.

In principle, manipulative experiments provide a preferable alternative, because their planning requires at least an implied prediction of the outcome, and making predictions is an integral part of science. The after-the-fact explanations mentioned earlier are sometimes called “predictions” by their promulgators, but there is no assurance that the information was not available before the prediction was made. There is no implication of dishonesty. The danger is as follows: All workers in ecology have a lot of factual information about the real world, and assuming that they are interested in understanding nature, they think about how things work. It is virtually impossible to separate known facts from the thought process. The knowledge is, perhaps unconsciously, taken into account in formulating hypotheses about how nature works. Thus, when a “test” is proposed, the prior knowledge is used, and the outcome is known in advance. Such a confirmation is, of course, spurious. I have selected an example from one of my own publications (Hairston 1964).