Two-step intertheory relationships: different realist interpretations

OLIMPIA LOMBARDI

Tartu

Simposio; Keynote Speaker: From ϕ-science to practical realism: an international conference in honour of Rein Vihalemm; 2019

University of Tartu

At present there is awide consensus regarding that realism in science cannot be disconnected fromthe practice of science itself. However, practice is usually conceived in termsof laboratory activities: science is practical due to its experimental side.But this view forgets that theoretical activities are also part of the practiceof science: theoretical scientific practice is also essential to thediscussions about realism. In this context, how the relationships betweenscientific theories are interpreted contributes to the discussions in asignificant way. In this talk I will beginby arguing that relevant cases of relationships between scientific theories-in particular, those traditionally conceived in terms of reduction- involve two steps, an intra-theoryrelationship and an inter-theoryrelationship, usually mediated by an intermediatetheory that supplies the link between the two original theoretical domains.I will illustrate this view with three examples, stressing the analogies amongthem: (i) thermodynamics and classical mechanics, mediated by classicalstatistical mechanics, (ii) classical mechanics and quantum mechanics, mediatedby the theory of decoherence, and (iii) structural chemistry and quantummechanics, mediated by the quantum theory of atoms in molecules (QTAIM). Finally,by focusing on the third example, I will consider how the two steps involved inthe relationship -the intra-theory step linking quantummechanics and QTAIM and the inter-theory step linking QTAIM and structuralchemistry- can be interpreted from differentrealist perspectives.