ECO takes for granted “that the world exists independently of our knowledge of it, and that it exists as a population of essences reciprocally governed by laws” (Kant and the Platypus 298). I will grant the first proposition easily. But I will grant neither part of the second. I don’t know what an essence is or why “things” ought to be recouped as essences in fact. Essences if they exist in any way do not exist as such; they exist, like all conceptual things, but for the purposes of the moment, for the use to which they are put for whatever meaning (in its broadest sense) a person has for a thing at that moment. Things have properties. But in what sense do they have essences? And as for “governed by laws,” how does the expression differ in meaning from “are describable by equations?” Perhaps Eco is thinking of “laws” other than the “laws” of the physical sciences. But I don’t think so. And these physical “laws” since Einstein have been understood to be not the Newtonian regularities, the same everywhere, but the descriptions of facts that obtain under certain conditions. We may be fooled by the fact that these conditions seems to obtain everywhere in the universe into believing that these conditions are the facts themselves, the fixed baseline of conditions as such. But of course that is not true. We believe that the the normal “laws” of physics do not obtain at the event horizon of a black hole. We do not know that they obtain everywhere else in the universe—but only that where they do not obtain we cannot see. And current thinking contents that in other possible universes, which may well exist “elsewhere,” very different laws of operation may obtain.
Science is only one way of thinking and perceiving. It is rigorous and useful. It is also true within the parameters in which it is situated. All scientific questions require scientific answers. And it is one of the neatest discursive formations we humans have ever discovered or constructed. Its only rival is math. But it is still only one way of thinking and perceiving. Its truths are scientific truths; they are not truths as such. Things are as they are, independent of any perceiver. I will grant this. (I can’t prove it, and there is a practical advantage to granting it, but the reason to grant it is that there is no compelling reason not to grant it, and it seems to be essential to grant it in order for anything to follow.) But facts are determined by the discourse and the conditions within that discourse in which the facts must be determined.
But all water is made of H20, isn’t it? If it were, I would not have to take my water into the city once a year to have it tested. My water is not composed merely of H20. It has all sorts of things in it, including trace levels of arsenic. It’s very hard I think to get any quantity of water that is composed entirely of H20 molecules, though if we do have a molecule of H20 it is certain, within our definition, that we have a molecule of water. Nonetheless, what counts as water depends on who wants it at a given point in time for a given purpose. What counts as water does not depend on the scientific definition of water.