Isabelle Pantin writes about divergent conceptual universes revealed by an episode in the history of optics ("Simulachrum, species, forma, image: What Was Transported by Light into the Camera Obscura? Divergent Conceptions of Realism Revealed by Lexical Ambiguities at the Beginning of the Seventeenth Century," Early Science and Medicine 13(2008), 245-269. The abstract:
At the end of the Renaissance, the complete understanding of the experiment of the camera obscura required dealing with the physical problem of the relationship between light and images. According to Kepler, this experiment demonstrated that the geometry and physics of light were one and the same thing and that there was no need for the luminous rays to transport any form of species. The Jesuits Fransiscus Auguilonius and Cristoph Scheiner were conscious of the superiority of Kepler's analysis of the camera obscura, but remained attached to the old theory of species. Scheiner's attitude was particularly significant. Although he had almost entirely assimilated the new Keplerian method of demonstration, he retained the traditional conception of realism. He still believed that the mediation of species was indispensable for making certain that what was seen was a real object.
I'll abstain from applying any lesson against relying on heterogeneous orders of knowledge in scientific endeavors, or against clinging to habits of thought that have been shown to be useless, because I have a few reservations about Pantin's conclusions. In the first place, and this might be worth glossing over if not for its irony, the evidence of exactly lexical ambiguity is weak and since, as Pantin points out, simulachrum, species, forma and imago are treated as synonymous by her sources, the question is really one of, in her words, "conceptual uncertainty." Perhaps an ambiguity in Kepler's restricted use of the word species allowed the basic concept of species to go unchallenged, for a brief moment in history, but what is most interesting in this case is the conceptual uncertainty. One might speak of cognitive dissonance if that term weren't so terribly abusedbesides, one really has the sense of the passage of a whole order of knowledge rather than a simple belief. (How could it have been thought that people might have become inured to the passages of whole orders of knowledge?)
To be truthful it's not clear to me that any hard and fast demarcation between "lexical ambiguity" and "conceptual uncertainty" can be maintained, though it seems handy enough as a provisional gesture, and so with a due sense of humility I object to the following claim: Pantin says that the camera obscura "showed that light could create images independently of sensation" (256). I venture that this claim does not represent anthropomorphismnot in the way a speculative misanthropy would require us to think anthropomorphically, for instancebut I will also say that as far as I know light does not create anything and as far as I know only psychic, animate existentialities create images. Further, I don't know if can has anything at all to do with light. On the other hand, Pantin's conception of realism possibly does fall among those that resemble a (cryptodeistic) Mechanism or an enfeebled animism, that is, an animism that can't summon the strength to declare itself as a faith. Thus I must for the moment maintain an ambivalence as to whether to assign my dispute with Pantin's realism to lexical ambiguity or to conceptual uncertainty. Perhaps you have some clearer thought on the matter?