We said earlier that all matter carries mutual information. This mutual information is an affordance which can be used by a system to gain value, i.e., move the environment towards a goal state, i.e., serve a purpose. So, for example, a bacterial food source may create particular sugar molecules which diffuse away from the source. (The source “causes” sugar molecules which float away). The sugar molecule has mutual information with respect to the source. If a bacterium can hook a mechanism to move to higher concentrations of this sugar molecule it will improve its chances of survival.
But maybe that same food source is toxic to a different bacterium. If this other bacterium can hook a mechanism to move to lower concentrations of the sugar, it will improve its own chances of survival.
So we can say mutual information is an affordance for meaning. The *meaning* of the information is determined by the mechanism which generates the response (output) to the information in the input.