Van Brakel, Jaap. “The nature of chemical substances.” Of minds and molecules: New philosophical perspectives on chemistry (2000): 162-84.
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Professor Hare, delivering the presidential address to the Aristotelian Society in Oxford in 1984, said: “It is commonly said that the property of being water supervenes on the chemical (or ultimately on the physical) property of being H2O. As it stands this view seems to me to be obviously false.” In terminology, that will become clearer as we proceed, Hare defended the manifest image—in this case, ordinary liquid water against elimination by the scientific image (which reduces “being water” to “being H2O”). Hare used the verb to supervene instead of to be reducible, but the difference between the two is slight (as we shall see in a later section). A more common view among philosophers and scientists is expressed in the following citation from Kim (1990, p. 14): “Chemical kinds and their microphysical compositions (at least, at one level of description) seem to strongly covary with each other, and yet it is true, presumably, that natural kinds are asymmetrically dependent on microphysical structures.” Kim takes the view that manifest objects are “appearances” of a reality constituted by systems of imperceptible particles. Such a view takes for granted that the macroscopic, manifest world is dependent on the microstructure of the world in such a way that it is underlying things that are more real and determine appearances. In crude jargon: science uncovers the Dinge-an-sich that explain the phenomena we see. I chose the quotations of Hare and Kim because both point to, though fail to address, the philosophical issue I discuss in this chapter, viz. the tension between manifest and scientific image, focusing on chemistry. “Manifest” versus “scientific” imagery talk stems from Sellars. The manifest image refers to things like water, milk-lapping cats, injustice-angry people, as well as sophisticated interpretations of “people in the world.” The scientific image is concerned with things like neurons, DNA, quarks, and the Schrödinger equation, again including sophisticated reflection and a promise of more to come. I use “manifest image” with a different inflection from Sellars, avoiding associations with sense data (which was an important part of his concern), associating it rather with forms of life.