Jacob McDowell

Every physical theory has two different forms of mathematical equations to represent its target systems: the dynamical and the kinematical. Kinematical constraints are differentiated from equations of motion by the fact that their particular form is fixed once and for all, irrespective of the interactions the system enters into. By contrast, the particular form of a system's equations of motion depends essentially on the particular interaction the system enters into. All contemporary accounts of the structure and semantics of physical theory treat dynamics, i.e., the equations of motion, as the most important feature of a theory for the purposes of its philosophical analysis. I argue to the contrary that it is the kinematical constraints that determine the structure and empirical content of a physical theory in the most important ways: they function as necessary preconditions for the appropriate application of the theory; they differentiate types of physical systems; they are necessary for the equations of motion to be well posed or even just cogent; and they guide the experimentalist in the design of tools for measurement and observation. It is thus satisfaction of the kinematical constraints that renders meaning to those terms representing a system's physical quantities in the first place, even before one can ask whether or not the system satisfies the theory's equations of motion.

I do not think the notion of rigidity in designation can be correct, at least not in any way that can serve to ground a semantics purports both to be fundamental in a semiotical sense and to the best science of the day. A careful examination of both content and the character of our best scientific knowledge not cannot support anything like what the notion of rigidity requires, but actually shows the notion to be, at bottom, incoherent. In particular, the scientific meaning of natural kind terms can be determined only within the context of a fixed scientific framework and not sub specie aeternitatis. Along the way, I provide grounds for the rejection of essentialist views of the ontology of natural kinds.

Polysemous concepts with multiple related meanings pervade natural languages, yet some philosophers argue that we should eliminate them to avoid miscommunication and pointless debates in scientific discourse. This paper defends the legitimacy of polysemous concepts in science against this eliminativist challenge. My approach analyses such concepts as patchworks with multiple scale-dependent, technique-involving, domain-specific and property-targeting uses (patches). I demonstrate the generality of my approach by applying it to "hardness" in materials science, "homology" in evolutionary biology, "gold" in chemistry and "cortical column" in neuroscience. Such patchwork concepts are legitimate if the techniques used to apply them produce reliable results, the domains to which they are applied are homogenous, and the properties they refer to are significant to describe, classify or explain the behavior of entities in the extension of the concept. By following these normative constraints, researchers can avoid miscommunication and pointless debates without having to eliminate polysemous patchwork concepts in scientific discourse.

I argue that an adequate semantics for physical theories must be grounded on an account of the way that a theory provides formal and conceptual resources appropriate for---that have propriety in---the construction of representations of the physical systems the theory purports to treat. I sketch a precise, rigorous definition of the required forms of propriety, and argue that semantic content accrues to scientific representations of physical systems primarily in virtue of the propriety of its resources. In particular, neither the adequacy of those representations nor any referential relations their terms may enter into play any fundamental role in the determination of the representation's semantic content. One consequence is that anything like traditional Tarskian semantics is inadequate for the task.