Abstract

In the seventeenth century, Newton published his famous experimentum crucis, in which he claimed that light is heterogeneous and is composed of (colored) rays with different refrangibilities. Experiments, especially a crucial experiment, were important for justifying Newton’s theory of light, and eventually his theory of color. Goethe conducted a series of experiments on the nature of color, especially in contradistinction to Newton, and he defended his research with a methodological principle formulated in “Der Versuch als Vermittler.” Goethe’s principle included a series of experiments and resultant higher empirical evidence as mediator between the objective (natural phenomena) and the subjective (theory or hypothesis). Although the notion of experimentum crucis became popular among scientists, even until today, in reconstructing experimental research and for justifying theories, especially for rhetorical purposes, I propose that Newton’s justification of his theory of light and color is best reconstructed in terms of Goethe’s methodological principle. Finally, Goethe’s principle has important consequences for the contemporary philosophical underdetermination thesis.