The development of knowledge

Interaction is the mode of life of living organisms. Each must feed on its environment, ingesting chemicals or other organisms. This is something more than "interaction", it is activity directed towards the environment. Since the organism must be selective in what it ingests, it needs to discriminate among the entities in its environment. From very primitive forms of discrimination, the sensory mechanisms of organisms have evolved into the senses of man, interpreted by an internal cognitive apparatus, memories of past experiences, and an ability to take rational decisions. By "rational" I mean activity that achieves intended results because it is based on a reliable understanding of the nature of the environment. In interacting with each other to carry out tasks jointly, men have further developed language, leading to a shared understanding of the environment. This shared understanding is knowledge. I am using the word "knowledge" in a wide sense, rather as Tylor used "culture": as the complex whole which includes all the capabilities acquired by man as a member of society, behaviour learnt through interaction with the environment. The purpose of this essay is to look at some of the ways in which this shared understanding has developed since earliest times