Abstract

I define the Gaia hypothesis as the descriptive claim, supposedly supported by biology and the earth sciences, that there's a fitness for one-and-all, and the owner of that fitness is Gaia. Much of the argument for Gaia turns on the supposed discovery of negative feedback loops serving its fitness. I present an argument against such a fitness, and so against Gaia. I distinguish two types of negative feedback systems. Systems in the engineering sense are information exploiters, whereas systems in the Boolean sense are simply producers of stability. I address three arguments presented by the advocates of Gaia for thinking that they have discovered a special variety of the Boolean system that is most supportive of Gaia's reality. I show that these arguments are specious. Furthermore I show that systems in the engineering sense would be the most supportive of the Gaia hypothesis, and no global feedback systems of that type have ever been found. These analyses have a constructive consequence of fundamental importance to biology: a theory of the way negative feedback, taken in the purely quantitative sense of information theory, comes to acquire the semantic character of being information about various features of an organism's niche