IS ECONOMICS SCIENTIFIC? IS SCIENCE SCIENTIFIC? – Part 3
By Phin Upham
The third part of Cartwright’s model is the simulacrum. She begins her discussion of simulacra by giving the secondary OED deﬁnition: “Something having merely the form or appearance of a certain thing, without possessing its substance or proper qualities.” The simulacrum moves away from reality in order to be able to generate laws. The process begins with a set of laws of phenomena but then develops causal relationships and fundamental laws. Cartwright envisions the simulacrum as a home to these laws.
In order to create the simulacrum, however, one must warp reality instead of reﬂecting the complex and rich world of phenomena. At the very least, the simulacrum must disregard the possibility that there are unknown forces outside of its conﬁnes. In this way it must necessarily put restrictions upon itself that differ from reality. The simulacrum might appear to be like the real world, but since it is constrained and warped, it is able to establish uniform and causal relationships and “fundamental laws” that are true only of the simple simulacrum, not of complex reality.
Simulacra are implicit in any law that postulates frictionless planes, perfect vacuums, evenly dense universes, and, more generally, gravity—-where no other forces counteract the fundamental law being examined. It would be coincidental, if it were even possible, to ﬁnd any object in reality that acts precisely as does as an object in the gravity simulacrum. Almost always things such as air (or any other medium that is not a perfect vacuum) and electric charges affect gravitational movement in unpredictable ways. Only in the simulacrum are the object’s movements explained solely by gravity. Only there do we find such theoretical entities as three—level atoms, and such quasi—realistic entities as electromagnetic fields and Classical electron oscillators. Other than the law of gravity, some examples of fundamental laws are the laws of quantum mechanics, Maxwell’s Equations, and E=MC2.
A fundamental law, for Cartwright, is a causal law that describes the entities in the simulacrum, but not entities in the world of phenomena. “It usually does not make sense to talk of the fundamental laws of nature playing out their consequences in reality. For the kind of antecedent situations that fall under the fundamental laws are generally the ﬁctional situations of a model, prepared for the needs of the theory, and not the blousy situations of reality” (Cartwright I983, 160). There— fore, Cartwright insists, “fundamental equations do not govern objects in reality, they govern only objects in the models” (ibid., 129). Fundamental laws do not apply to reality, Cartwright argues, because the very fact that they are able to explain a broad number of phenomena implies that they distort the reality of a “dappled” world.
Reality, Cartwright insists, is necessarily much more complicated than any model. Because reality is internally disuniﬁed, different laws interact in the real world in ways that are not additive, but rather are intrinsically unpredictable in principle. Cartwright gives the example of calculating the attraction of two objects that are both massive and charged. When Coulomb’s Law (which gives the force between charges) intersects the law of universal gravitation, the two laws interact in such a way as to make them both wrong, and the new attraction between the two objects is not explained by merely adding or subtracting the two laws. “For the fundamental laws of physics do not describe true facts about reality. Rendered as descriptions of facts, they are false; amended as true, they lose their fundamental explanatory force” (Cartwright I983, 54). Nature, in Cartwright’s View, has pro— vided an untidy palate with which to paint laws. We must apply laws piecemeal in order to capture even a part of this reality. After all, “what [fundamental laws] govern has only the appearance of reality and the appearance is far tidier and more regimented than reality itself ” (ibid., 162).
The fact that fundamental laws and simulacrum models are not completely faithful representations of reality not only isn’t a problem for Cartwright; in her View, it is one of the strengths of her analysis. We are able to use our few fundamental laws readily and fruitfully because they are simple and, therefore, inaccurate. “The great explanatory power of quantum mechanics comes from its ability to deploy a small number of well understood Hamiltonians to cover a broad range of cases, and not from its ability to match each situation one—to—one with a new mathematical representation. That way of proceeding would be crazy,” she writes. “The beauty and strength of contemporary physics lies in its ability to give simple treatments with simple models, Where at least the behavior in the model can be understood and the equations can not only be written down but can even be solved in approximation” (Cartwright 1983, 144—45).
This works so well because the simpliﬁcations and assumptions of the simulacra are not random. They are specifically crafted so that a fundamental law can operate causally upon the entities in the model. “A model is a work of fiction. Some properties ascribed to objects in the model will be genuine properties of the objects modeled, but others will be merely properties of convenience” (Cartwright 1983, 153). Thus, It is important that the models we construct allow us to draw the right conclusions about the behavior of the phenomena and their causes. But it is not essential that the models accurately describe everything that actually happens; and in general it will not be possible for then to do so. . . . This does not mean that the right lessons cannot be drawn.
So here is the tradeoff. The less accurate we make our fundamental laws (or, stated a different way, the more untrue to reality we make our Simulacra), the broader the causal and explanatory power we may get. Cartwright (1983, I49) maintains that we seek two different sorts of realism when constructing a model. We want a realistic relationship between the model and the world, where “the model is realistic if it presents an accurate picture of the world: it describes the real constituents of the system the substances and ﬁelds that make it up—and ascribes to them characteristics and relationships that obtain.” At the same time, there should be a realistic relationship between the model and the mathematics of fundamental laws—which, in order to be precise, have to be unfaithful to over determined and imprecise reality.
Cartwright’s framework is now complete. The fundamental laws apply to the objects in the simulacrum, which, at best, approximate the behavior we would expect based on laws that describe particular phenomena of the real world. The simulacrum is a ground between the two kinds of law. Simulacra must be such that the fundamental laws are true—that is to say, causal of the objects in them (and such that we can derive an account of how the objects behave). At the same time, simulacra must be such that the fundamental laws are closely tied to at least some bits of reality (or else the simulacrum might be a theory that would have no practical use). “The simulacrum account is not a formal account. It says that we lay out a model, and within the model we ‘derive’ [through an admittedly unexplained mechanism] various laws which match more or less well with bits of phenomenological behavior” (Cartwright 1983, 161).