Taking into account Stephen Toulmin´s approaches, we will look at some aspects in the historical development of Chemistry connected to the concept of substance. In a superficial and non-linear manner, the text tries to show some complex networks that developed between the diverse components named by Toulmin as "intellectual ecology", such as the niches of rationality and the representations among them. This aproximation to the outcoming allows to identify the questions and the problems which with different meanings, emphasis and shades are still current; explanatory models which have pretended giving an answer to those questions and some forms of validity which permit the contextual acceptance of them. Finally, we propose possible implications of these analysis to teaching.
Rationality; Argumentation; Representation; Evolution; Substance
