Ioannis Votsis

Structural realism has various diverse manifestations. One of the things that structural realists of all stripes have in common is their endorsement of what I call 'the structural continuity claim'. Roughly, this is the idea that the structure of successful scientific theories survives theory change because it has latched on to the structure of the world. In this talk I elaborate, elucidate and modify the structural continuity claim and its associated argument. I do so without presupposing a particular conception of structure that favours this or that kind of structural realism but instead by concentrating on neutrally formulated historical facts. The result, I hope, throws light on what a structural realist must do to evidentially benefit from the historical record of science. The implicit argument underwriting the structural continuity claim can be reconstructed as follows: Premise (1) Only structural elements of predictively and explanatorily successful scientific theories have been (and will be) preserved through theory change. Premise (2): Preservation of an element implies or at least is good evidence for its (approximate) truth. Premise (3): Non-preservation of an element implies or at least is good evidence for its falsity. Conclusion: It is probably the case that only structural elements are (approximately) true. In this summary I restrict my comments to the first premise. Several points can be raised with respect to it. First, not all structures are created equal. Some play no active role in the predictive and explanatory success of a theory because they do not correspond to any structure in the world. Their non-preservation would therefore not encumber the structural realist. Traditional scientific realists have long employed a distinction between essential and idle posits to weed out those elements of theories that played no substantial role in their predictive and explanatory success..

Let us call ‘veridicalism’ the view that perceptual beliefs and observational reports are largely truthful. This paper aims to make a case for veridicalism by, among other things, examining in detail and ultimately deflating in import what many consider to be the view’s greatest threat, the so-called ‘theory-ladenness’ of perception and/or observation. In what follows, it is argued that to the extent that theoretical factors influence the formation of perceptual beliefs and observational reports, as theory-ladenness demands, that influence is typically not detrimental to their veridicality or at least not irreversibly so. Central to the defence of veridicalism are two principles: that of internal similarities and that of internal dissimilarities.

In scientific realist eyes we are only warranted to assert that a theory is true or approximately true if that theory enjoys considerable explanatory and predictive success. The most well known challenge to this claim, the pessimistic meta-induction, holds that the history of science is replete with successful theories that are now considered false. In effect, this challenge raises doubts about the reliability of inferences from explanatory and predictive success to (approximate) truth. The main realist reaction has been to argue that upon closer scrutiny the historical record can be reconciled with scientific realism. When a successful theory is abandoned, not all of its components are discarded but only those that are inessential or idle for the theory’s success. Their abandonment is thus inconsequential for the realist. In this talk I consider what the modern kinetic theory of heat managed to salvage from the outdated caloric theory and whether the inter-theoretic relations between the two theories support a realist view of science