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 | |  Naturalistic Ontology | |
In recent years properties have played a central role in philosophical accounts of scientific realism, measurement, causation, dispositions, and natural laws. This is a less unified set of concerns than those encountered in the previous two subsections, but it is still a clearly recognizable area, and we will call it naturalistic ontology. Let us see how properties enter the picture in this field.Even quite modest and selective versions of scientific realism are most easily developed with the aid of properties. Most importantly, this is so because claims that appear to quantify over properties are common in science, as these examples show:
- If one organism is fitter than a conspecific, then there is at least one property the first organism has that gives it a greater propensity to reproduce than the second.
- There are many inherited characteristics, but there are no acquired characteristics that are inherited.
- Properties and relations measured on an interval scale are invariant under positive linear transformations, but this isn’t true of all properties and relations measured on ordinal scales.
- In a Newtonian world all fundamental properties are invariant under Galilean transformations, whereas the fundamental properties in a special-relativistic world are those that are invariant under Lorentz transformation.
No one has any idea how to paraphrase most of these claims in a non-quantificational idiom, and they certainly seem to assert (or deny) the existence of various sorts of properties; naturalproperties, one may say in the terminology of Lewis (1983), who takes naturalness as coming in degrees, so that we may speak of perfectly natural properties, perhaps negatively charged, less than perfectly natural properties such as metallic, and completely unnatural ones, e.g., Goodman’s notorious grueness (see Dorr & Hawthorne 2013 for a detailed analysis of what naturalness amounts to).Many important properties invoked in science, like being a simple harmonic oscillator, being a gene, being an edge detector, or being a belief, are often thought to be functional properties. To say that something exemplifies a functional property is, roughly, to say that there are certain properties that it exemplifies and that together they allow it to play a certain causal role. For example, DNA molecules have certain properties that allow them to transmit genetic information in pretty much the way described by Mendel’s laws. Here again, we have quantifications over properties that seem unavoidable.Much explanation in science is causal explanation, and causal explanations often proceed by citing properties of the things involved in causal interactions. For example, electrons repel one another in the way that they do because they have the same charge.In naturalistic ontology we often hear claims that one sort of thing is reducible to a second or (more frequently nowadays) that one sort of thing supervenes on another. Such claims make the best sense if we take them to involve properties. For example the claim that the psychological realm supervenes on the physical realm involves mental and physical properties.Some philosophers of science, most notably Feyerabend and Kuhn, argue that theoretical terms such as ‘mass’ draw their meaning from the theories within which they occur. Hence, they conclude, a change in theory causes a shift in the meanings of all of its constituent terms, and so different theories simply talk about different things, they are ‘incommensurable.’ The common realist rejoinder is that the reference of terms can remain the same even when the surrounding theory shifts. But for this response to work a theoretical term must refer to something, and the most plausible candidate for this is a property.Various features of measurement in science are most easily explained by invoking properties. For example, estimates of the magnitude of measurement error are typically reported along with measurement results. Such talk makes little sense unless there is a fact about what a correct measurement would be. But the very notion of correct measurement seems to imply that objects exemplify magnitude properties such as rest mass of 4kg. Moreover, nowadays measurement units are often specified directly in terms of properties. For instance, we now specify the meter in terms of something that can in principle be instantiated anywhere in the world, e.g., as the length equal to a certain number of wavelengths (in a vacuum) of a particular color of light emitted by krypton 86 atoms (Mundy 1987; Swoyer 1987).Some philosophers have employed properties in reductive accounts of causation (cf. Tooley 1987; Fales 1990). It would take us too far afield to explore this work here, but it is worth noting that it is never a single, undifferentiated amorphous blob of an object (or blob of an event) that makes things happen. It is an object (or event) with properties. Furthermore, how it affects things depends on what these properties are. The liquid in the glass causes the litmus paper to turn blue because the liquid is an alkaline (and not because the liquid also happens to be blue). This suggests that at least some properties are causal powers.Properties have played a central role in several recent accounts of natural laws. This is particularly evident in what we will call N-relation theories, according to which a natural law is a second-order relation of nomic necessitation (N, for short) holding among two or more first-order properties. Hence the logical form of a statement of a simple law is not ‘All Fs are Gs’; in the case of a law involving two first-order properties, it is a second-order atomic sentence of the form ‘N(F,G)’ (see, e.g., Armstrong 1978a; 1983; Dretske 1977; Tooley 1977).In the more exact sciences the relevant first-order properties (our Fs and Gs) will typically be determinate magnitudes like a kinetic energy of 1.6 × 10−2 joule or a force of 1 newton or an electrical resistance of 12.3 ohms (rather than mass or force or resistance simpliciter; Knowles 2015 argues interestingly for the controversial view that these properties are relations to numbers). Hence the laws specified by an equation are really infinite families of specific laws. For instance, Newton’s second law tells us that each specific, determinate mass m (a scalar, and so a monadic property) and total impressed force f (a vector, and so a relational property) stand in the N-relation to the appropriate relation (vector) of acceleration a (= f/m).The dominant accounts of laws during much of the last century were regularity theories, according to which laws are simply contingent regularities and there is no metaphysicaldifference between genuine laws and accidentally true generalizations. N-relation theories were originally devised to avoid perceived shortcomings of these earlier accounts, such as their failure to account for the modal force and the objective character of natural laws. Many laws seem to necessitate some things and to preclude others. Pauli’s exclusion principle requires that two fermions occupy different quantum states and the laws of thermodynamics show theimpossibility of perpetual motion machines. But, N-relation theorists insist, since regularity theorists forswear everything modal, they can never account for the modal aspects of laws. Moreover, according to N-relation theories, laws are objective because the N-relation relates those properties it does quite independently of our language and thought (in the case of properties that don’t specifically involve our language or thought). By contrast, the epistemic and pragmatic features used by regularity theorists to demarcate laws from accidental generalizations are too anthropocentric to account for the objectivity of laws.N-relation theories are not without difficulties (Van Fraassen 1989). First, it is not clear how to extend N-relation accounts to deal with several important kinds of laws, most prominently conservation laws and symmetry principles. Second, even in the case of laws that can be coaxed (or crammed) into the N-relation scheme, the account involves a highly idealized notion whose connection to the things that go by the name ‘law’ in labs and research centers is rather remote (attempts to remove this gap typically rely on Cartwright 1983; 1989). However, if N-relation accounts are on the right track, there is a reasonably rich realm of properties that is structured by one or more nomic relations.The work discussed in this subsection suggests that properties include determinate physical magnitudes like mass of 3.7 kg and electrical resistance of 7 ohms. Furthermore, such properties typically form families of ordered determinates (e.g., the family of determinate masses) that have a definite algebraic structure (Mundy 1987; Swoyer 1987). It also suggests that a fundamental feature of at least many properties is that they confer causal capacities on their instances. Work on naturalistic ontology doesn’t entail detailed answers to every question about the nature of properties, but it does suggest answers to some of them. | |
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