NEWTONIAN INTELLIGIBILITY: SATIS EST
sea.”[185] Newton limits his class of “everything” to a broad range of phenomena he seeks to explain in his present investigation. This is so as well for the depth of the explanation.
He is not attempting to discover a complete set of fundamental laws and objects that can explain all phenomena in nature at the deepest level.Are the explanations he offers “incomplete”? There are different ways this question could be answered, since there are different ways or respects in which an explanatory task can be considered complete or incomplete. Newton's explanations are incomplete in the sense that they don't answer all questions that might be raised, or even ones he himself raised about the phenomena he considered (e.g., What causes gravity to be exerted between bodies?). Nor do they answer the questions they do by invoking fundamental properties and laws governing basic “atoms” in the universe. In these respects, they are not “complete.” The explanations they give are not derived from a TOE. But there is another way to judge completeness. It is one that is relativized to the Newtonian context, to the specific project Newton sets for himself in the Principia. That project is to begin with established astronomical facts about the Keplerian motions of the planets and their moons; show how these facts provide strong evidence for the law of gravity by “deducing” the latter from the astronomical facts using his three laws of motion and theorems that follow from them; and then show how the motions of celestial bodies, and other phenomena such as the tides, can be explained from the law of gravity. Does he complete this project?
What does such “completion” require? If it requires that the law and explanations offered be correct, then Newton did not complete the project. If it requires only that Newton present evidence for the law and show how to give the explanations, then whether he completed the project depends on the sense of evidence in question.
He did not supply veridical evidence, since the law is not true. Nor, as I have argued, did he supply ES-evidence—he needed more observations. He did supply subjective evidence—observational facts he believed constituted veridical evidence for his law. And he did furnish the explanations. So, he certainly believed that he completed his project, even if, using an objective concept of evidence, he was mistaken. But when “completion” is understood using an objective concept of evidence, it is not that his project was incomplete because his explanations were not derived from a TOE that is correct and for which there is objective evidence. His project was incomplete because his explanations were not derived from a law that is correct and for which there is objective evidence.One important way to understand “intelligibility” is as relativized to a project in which one is attempting to explain a set of phenomena and to provide evidence for its correctness. If the project is completed, and an explanation of the type sought is correct, then the “intelligibility” of the phenomena is complete with respect to that project—with respect to the questions raised, the level at which they are raised, and standards of completeness set by the project. This is what I have called “Newtonian intelligibility,” even if Newton did not himself achieve it. His aim was to do so, his attempt was monumental, and, most important for present purposes, it is the type of intelligibility that all but entrenched skeptics believe scientists can and should try to achieve. To be sure, even
258 | SPECULATION: WITHIN AND ABOUT SCIENCE if the explanation provided is correct and meets standards set by the project, other projects may require that the sort of explanation provided be at a different level and that a different standard of completeness for intelligibility be met. But that is still “Newtonian intelligibility,” now relativized to a different project.
James Clerk Maxwell is also a defender and practitioner of “Newtonian intelligibility” (despite his view noted earlier about the fundamentality of dynamical explanations).
He writes: “In all scientific procedure we begin by marking out a certain region or subject as the field of our investigations. To this we must confine our attention, leaving the rest of the universe out of account till we have completed the investigation in which we are engaged.”[186]This does not mean that scientific inquiry ends when “Newtonian intelligibility” has been achieved—when the problem at issue is solved at some contextually determined appropriate level. Other tasks usually await us. But the idea behind “Newtonian intelligibility” is that whether, or to what extent, a theory has been established that provides complete intelligibility is to be evaluated, not just by how the world is but also by specific requirements of the inquiry.[187] The inquiry can change as more information is discovered, further questions are raised, and new requirements set, so that what is complete in one inquiry and context is not complete in another. If you judge completeness solely by reference to the way the world is, then you ignore what I earlier called the “scientific perspective.” To claim that unless a TOE is
produced and established the world is not completely intelligible is to do just that.
9.