Introduction
A prominent response to Larry Laudan's skeptical reading of the history of science rejects the view that empirical theories fall flat if either their central terms fail to refer or some of their assertions are seriously wrong.
A false theory, realists argue, can still be approximately true in the sense of having parts that have high truth-content—we just need to identify those parts in some principled way, hence the labels “Selectivism” and “Selective Realism.” In the 1980s and 1990s, selec- tivist efforts to identify truthful content tried to distinguish between working or essential posits on the one hand and idle or inessential posits on the other. Fresnel's theory of light was presented as an exemplar case. Embedded in now rejected assumptions (notably about the existence and character of the ether luminiferous), Fresnel's theory nonetheless contains reliable content at some theoretical levels of description. Light is not completely as Fresnel imagined, yet light is made of microscopic transversal undulations, as Fresnel thought, and these fluctuations follow the laws of reflection and refraction he derived. The general theory-parts obtained by abstracting Fresnel's original proposal from his account of the ether— the wave substratum—spell out a “thinned out” description (call it “Fresnel's core”). This core is of reduced specificity relative to the original theory, but it comprises content which in fact all subsequent theories of light have retained. Selectivists point to this comparatively abstract core as their paradigmatic recipient of likely realist content in successful theories.In the 1990s and early 2000s, the leading strategy[78] run as follows: To identify what a successful theory gets right (a) look for parts that seem indispensable for making the theory's winning predictions; (b) in the case of past theories, check that in subsequent theories the parts in question have been retained and deemed approximately correct; and (c) propose those parts as both descriptive of theoretical aspects of the intended domain and responsible for the theory's success. Objectors voiced complaints along several lines.
One focused on posits once regarded as central to a theory's success only to be rejected by subsequent science—like the ether, phlogiston, and caloric (Chang 2003). More corrosive complaints included Lyons (2006)'s argument that metaphysical and even mystical beliefs, weak analogies, erroneous calculations, and logically invalid reasoning often seem “centrally responsible” for the success of theories. Much in these objections is fair. In mature scientific disciplines, theories are typically constructs tight enough to make breaking them into independent parts exceedingly difficult. Breaking into parts is particularly troublesome in theorizing that proceeds under traditional metaphysical constraints (as virtually all pre-Einsteinian theorizing did). In the case of the ether of light, the proposals by Fresnel, Arago, Maxwell, Hertz, and Lorentz, all invoked the subsequently discarded ether. Contrary to Psillos (1999)’s suggestion, it seems that the predictions these thinkers derived from their ether-based theories could not have followed paths that actually bypassed the ether, not least because all the alternative theories then at their disposal partook of a metaphysical framework in which waves (and fields) stood as modes of being and as such something in need of a substratum (Cordero 2011).The point is that, in advanced scientific disciplines, posits are very rarely “idle” or “inessential”.[79] Responding to the challenge, over the last decade some reformed selectivists have sought to address the suggested complaints by sharpening up selectivism. The resulting proposals tilt the project towards the minimalism of structural realism. At the center of these contributions are recent works by Juha- Saatsi (2005, 2011), Peter Vickers (2013), and IoannisVotsis (2011) [SVV], whose focus is on the truth and falsity content of descriptive claims seemingly needed for deriving impressive predictions from theories.
2