Structural Realism

Structural Realismi Edson Siquara de Souza Is structural realism the best of both worlds? We know that the life we live today is fundamentally a heritage of the scientific development of the past three hundred years and that what we know about the universe is what science tells us. We also know that theories just get close to the truth and end up been replaced by new ones that provide either a better overall understanding of reality or just add more accuracy. With that in mind, it seems to be fair to doubt theories about the behavior and structure of the world, but at the same time, it is hard to believe that someone could completely dismiss Newton´s equations and its powerful explanations about what we observe around us just because it lacks precision compared to General Relativity. The same applies to Einstein´s curved space-time structure that we can´t even see and all the stuff quantum mechanics says there is. Although we have this overall good feeling that science is a successful enterprise, there is this uneasiness associated with explanations of the world that requires the existence of things that are unobservable. In the pursuit of the final truth, science has more frequently been using references to objects that are undetected with current technology: entities that “must” exist in order for the equations to make sense. Should we trust science when it says that unproved objects exist? If we do, why can´t we trust religion for instance, or any other pseudo-science that are also in the business of explaining the world? This essay argues that Structural Realism is probably the best approach to show that the right position to take is actually a reconciliation of two opposing arguments, one that speaks for realism and another against it1. There are two divergent views about the specific case of the unobservable in science: according to the Stanford Encyclopedia of Philosophy (SEP) the “Scientific Realism is the view that we ought to believe in the unobservable entities posited by our most successful scientific theories”2. The opposing view, known as Antirealism, states that science “… is only powerful enough to yield knowledge regarding observables”3.

1 WORRAL, John; Structural Realism: The Best of Both Worlds?; Dialectica, 1989, Vol.43, p.101

2 http://plato.stanford.edu/entries/structural-realism/ (access 03-18-2015) 3 http://plato.stanford.edu/entries/scientific-realism/#ThrDimReaCom (access 03-18-2015)

The realists usually defend their view using the no-miracle argument offered by Hilary Putnam (1926), which states that science would be miraculous if scientific theories were not at least approximately true descriptions of the world4. This means that science has been proving to be so successful that somehow the entities it refers to must be “latched onto the blueprint of the universe”5. The antirealists, with their ´pessimistic meta-induction´ view, are skeptical about the realists position because looking back at the history of science we realize that successful theories were abandoned, been replaced by new and more advanced ones, meaning that it is expected that the current progressive theories will probably change in the future regardless of its today´s apparent success. Therefore, new entities will possibly replace those that belong to the older theories, so science cannot be serious when dealing with the nature of things. Structural Realism is an idea introduced by John Worrall (1946) where he tries to bring ´the best of both worlds´. According to James Ladyman “structural realism is the view that our best scientific theories describe the structure of reality, where this is more than saving the phenomena, but less than providing a true description of the natures of the unobservable entities that cause the phenomena”.6 In 1989 Worrall used the case of the transition in nineteenth century optics from Fresnel´s elastic solid ether theory to Maxwell´s theory of the electromagnetic field7 to demonstrate that the move from one to the other were structural in nature. He also referred to Newton-Einstein case, stating that although Newton´s theories were not wrong, Einstein´s were closer to the truth. This distinction is important because even if the objects or the causes of the phenomena used by those theories were different, it is clear that we consider the closeness to the truth to be of greater relevance. In Worrall´s interpretation of the shift from one theory to the other, he sees that it was not only a matter of carrying over empirical data to be better explained by the new theory, but “to exhibit cumulative growth at the structural level combined with radical replacement of the previous ontological ideas”8. Worrall wanted to show that “we should adopt the structural realist emphasis on the mathematical or structural 4 http://plato.stanford.edu/entries/structural-realism/ (access 03-18-2015) 5 WORRAL, John; Structural Realism: The Best of Both Worlds?; Dialectica, 1989, Vol.43, p.99 6 LADYMAN, James; ROSS, Don; Every Thing Must Go – Metaphysics Naturalized; p. 67; Oxford 7 LADYMAN, James; Understanding Philosophy of Science; p. 260 8 8 WORRAL, John; Structural Realism: The Best of Both Worlds?; Dialectica, 1989, Vol.43, p.120

content of our theories” 9 , and simply deny a straightforwardly acceptance of the standard realism thesis, but, at the same time, avoiding been antirealists about science. If Worrall is right, we have to see science as an enterprise that aims to explain the workings of the universe as a mathematical structure, accepting the fact that will keep developing, getting us closer and closer to the truth and, sometimes, in need to replace old references to entities by new ones. He is not saying that the universe comes from an equation that started it all; he is simply saying that the objects that concerns the antirealists can be a structure in which its nature is less relevant or nonexistent and what is important is the overall understanding of reality using the best tool to describe it, which is math. Although Worrall´s position has gained enormous attention, it has also received comments showing some of its weakness or ambiguities, like whether is more towards metaphysics or epistemology. LADYMAN (2002 : 261), for instance, believes that Worrall “put an epistemic constraint on realism to the effect that we only commit ourselves to believing in the structural content of a theory, while remaining agnostic about the rest”; but he himself mentions in LADYMAN and ROSS (2006 : 13) that “a first approximation to his own metaphysics is that ´There are no things. Structure is all there is.´” Worrall in his defense to Structural Realism was clearly moving towards Quantum Mechanics to make his point even more evident, since we can recognize it as the best theory we have that explains the building blocks of the universe. However, Quantum Mechanics also tell us about things we do not observe, like particles, fields, things that are and are not, etc. Quantum Mechanics is powerful to explain phenomenon, but is it powerful enough to convince non-scientists about the entities it relates to? The Cartesians usually prefer to avoid that, since there is this sort of prejudice that the World should be explained accordingly to the experience we have of it; but it is not necessarily so. According to Worrall, “The structural realist simply asserts…that, in view of the theory´s (quantum mechanics) enormous success, the structure of the universe is (probably) something like quantum-mechanical. It

9

LADYMAN, James; Understanding Philosophy of Science; p. 261

is a mistake to think that we need to understand it in classical terms.”10 If Structural Realism is right, we ought to see science´s aim in terms of explaining the universe with higher and higher precision, without necessarily telling us what kind of stuff it is made. This is definitely not easy to understand since science started explaining what we observe, but the nature of reality seems to keep challenging scientist to have new approaches. If the building blocks of the universe is not a particle or a string (the best bet we have to find the final truth), we have to take seriously the possibility that the universe is a continuum, a structure that its constituents cannot explain the hole; but mathematical formulations and relations within the structure can be the best way to understand what it is real. This means that if there is not a fundamental particle out there, we should not demand science to find one; science is not committed to find this entity, it is committed to find the truth or the closest thing possible. Therefore, for the antirealists and Cartesians alike, the best of both worlds is the one that bring us closer to the truth.

10 WORRAL, John; Structural Realism: The Best of Both Worlds?; Dialectica, 1989, Vol.43, p.164

BIBLIOGRAPHY

WORRAL, John; Structural Realism: The Best of Both Worlds?; Dialectica, 1989, Vol.43(1‐2), [Peer Reviewed Journal]

http://plato.stanford.edu/entries/structural-realism/ (access in 03-18-2015)

http://plato.stanford.edu/entries/scientific-realism/#ThrDimReaCom (access in 03-18-2015)

WORRAL, John; Structural Realism: The Best of Both Worlds?; Dialectica, 1989, Vol.43(1‐2), [Peer Reviewed Journal] LADYMAN, James; ROSS, Don; Every Thing Must Go – Metaphysics Naturalized; Oxford; 2007

LADYMAN, James; Understanding Philosophy of Science; 2002

This paper was written as the final assignment in the course Philosophy of Science at Oxford University. i