This paper proposes a biosemiotic conception of theories, as non-intentional organic theories, which is based on an analysis and comparison of philosopher Norwood Russell Hanson’s account of theories and zoologist Jakob von Uexküll’s theory of organisms. It is argued that Hanson’s proposals about scientific theories and their relation to observation are semiotic in nature and that there exists a correspondence between Hanson’s depiction of the relationship between theories, observation, and reality and von Uexküll’s views on the relationship between organisms and (...) their environments. This correspondence supports an account of theories that depicts them as organic extensions of our perceptual physiology. Among the epistemological consequences of this account are the following: The kind of correspondence that is established through theories between a subject and reality is related rather to a subject’s actions than to a faithful representation of every aspect of the world, it suggests a strong emphasis on the creative aspects of knowledge acquisition, and it urges a reassessment of the evolutionary epistemology of theories. (shrink)