Though Einstein did not formulate his own standpoints in philosophical terminology, we may tentatively summarise them as follows:
(1) The immanent epistemology in the forma/ principles of Einstein's theory, especially the special and the general principles of relativity. According to this epistemology, such entities as absolute space, absolute time, and absolute inertial systems, should be excluded from the physical theories. Natural phenomena, observed from a certain standpoint (coordinate system of reference), should not be considered as absolute, but always as relative to some observers. But the same principle prohibits the existence of a privileged observer. All observers are equal, for it is postulated that the natural laws should be formulated in such a way that the same mathematical forms hold in every system of reference.
(2) The essentialism implicit in the material principles of Einstein's theory, such as the constant velocity of light, and the principle of equivalence. These principles, though empirically refutable, should give some information about the essential structures of the world. For example, the constant velocity of light plays the essential role of mediation between mass and energy. The principle of equivalence, if accepted, would necessarily reform our ideas of space and time. We must adopt the curved space of non-Euclidean geometry in the presence of a gravitational field.
(3) The deterministic world-view in the background of Einstein's cosmology. The characteristic of relativistic cosmology is that uncertainty, or contingency totally disappears in the four dimensional space-time: everything should be determined sub specie aeternitatis. The appearance of contingency is due to our ignorance of necessity. It was this kind of Spinozism that forced Einstein to reject the non-deterministic interpretation of quantum mechanics.
In order to estimate a physical theory, it is not enough to understand its philosophical background. We must also know to what extent it has passed through the empirical tests. What we must bear in mind is that while the special theory of relativity, with its abundant empirical supports, has won the approval of almost every physicist, the general theory of relativity, in spite of its philosophical importance, has been treated, not as decisive, but as one of many competing gravitational theories. This is because of the comparatively few number of crucial tests, whose accuracy has often proved not sufficient enough to be reliable. It is not without reason that the general theory has been isolated from other advanced fields of physics. But thanks to the improvement of experimental techniques and the development of astronomy, the general theory of relativity has again become the center of interest among experimental physicists.
There are many theories of gravitation known as varieties of Einstein's theory, e.g. Brans-Dicke theory. famous for being faithful to Mach's principle, scalar- and vector-tensor theories, etc. From the philosophical point of view, the most interesting is Whitehead's theory of relativity. This theory, originally published in 1922, has a different paradigm from Einstein's, elegant and simple in mathematical formulation with its own philosophical background. It has been called as "a thorn in Einstein's side", because it agrees with Einstein in its prediction for all the classical tests. Whitehead's theory is closely connected with his philosophy of nature and his metaphysics. We cannot understand it without paying due attention to his philosophy. Comparing it with Einstein's theory, we may summarize the main oppositions between them as follows:
( 1) Whitehead's theory does not presuppose "the principle of relativity" in Einstein's sense. It contains a subsystem which corresponds to Einstein's theory of special relativity, but it can do without "the principle of special relativity" and "the principle of the constant velocity of light." For example, it derives the Lorentz Transformation only in terms of the weak condition concerning the symmetry and uniformity of space-time. Moreover, "the principle of general relativity" does not hold in Whitehead's theory of gravitation, in which the inertial systems are not equivalent to the rotating systems of reference.
(2) Whitehead rejected "the principle of equivalence" which was the cornerstone of Einstein's theory oj'genera/ relativity. According to Whitehead, there is no reason why we should give privileged status to gravitational fields with respect to the space-time metric. They should be treated on a par with other physical fields. The gravitational and inertial forces are, therefore on principle, distinguished from each other in his theory.
(3) Whitehead did not adopt the deterministic world-view in his background cosmology. According to his philosophy of nature, natural laws only partially restrict future contingency. The concept of matter as the substance of nature disappears with his rejection both of Cartesian dualism and of Spinoza's monism. The concept of event, or of duration which is the field of creative becoming, plays the central role in his theory.
Thus we have to say that Whitehead's theory is different from Einstein's with respect both to the formal and to the material principles, in addition to the difference of world-views in the background.
I don't intend to decide by an outside criterion which theory is better, but to consider each in its own context. It is not easy for us to compare between theories with different paradigms, and the simple data cannot tell us crucial matters by themselves. What we want is the integration of the two paradigms. This does not mean that the problem of empirical tests might well be devalued. On the contrary, as long as we discuss physics, we must try to formulate theories in such a way that they are refutable by possible observation. The problem is that there exists a difference between them concerning the kind of principles that are subject to empirical refutation.
Whitehead once said of Einstein that "the worst homage we can pay to genius is to accept uncritically formulations of truths which we owe to it." This kind of critical spirit will become the guiding thread in the following consideration, with proviso that it should be the case with Whitehead as well.
What we must notice before discussing empirical tests is that Whitehead's principle of relativity has a different meaning from that of Einstein's. Taking into consideration the importance of the Whiteheadian relativity principle, we must first make clear what he means by it in the context of his own philosophy.
(1) The immanent epistemology in the forma/ principles of Einstein's theory, especially the special and the general principles of relativity. According to this epistemology, such entities as absolute space, absolute time, and absolute inertial systems, should be excluded from the physical theories. Natural phenomena, observed from a certain standpoint (coordinate system of reference), should not be considered as absolute, but always as relative to some observers. But the same principle prohibits the existence of a privileged observer. All observers are equal, for it is postulated that the natural laws should be formulated in such a way that the same mathematical forms hold in every system of reference.
(2) The essentialism implicit in the material principles of Einstein's theory, such as the constant velocity of light, and the principle of equivalence. These principles, though empirically refutable, should give some information about the essential structures of the world. For example, the constant velocity of light plays the essential role of mediation between mass and energy. The principle of equivalence, if accepted, would necessarily reform our ideas of space and time. We must adopt the curved space of non-Euclidean geometry in the presence of a gravitational field.
(3) The deterministic world-view in the background of Einstein's cosmology. The characteristic of relativistic cosmology is that uncertainty, or contingency totally disappears in the four dimensional space-time: everything should be determined sub specie aeternitatis. The appearance of contingency is due to our ignorance of necessity. It was this kind of Spinozism that forced Einstein to reject the non-deterministic interpretation of quantum mechanics.
In order to estimate a physical theory, it is not enough to understand its philosophical background. We must also know to what extent it has passed through the empirical tests. What we must bear in mind is that while the special theory of relativity, with its abundant empirical supports, has won the approval of almost every physicist, the general theory of relativity, in spite of its philosophical importance, has been treated, not as decisive, but as one of many competing gravitational theories. This is because of the comparatively few number of crucial tests, whose accuracy has often proved not sufficient enough to be reliable. It is not without reason that the general theory has been isolated from other advanced fields of physics. But thanks to the improvement of experimental techniques and the development of astronomy, the general theory of relativity has again become the center of interest among experimental physicists.
There are many theories of gravitation known as varieties of Einstein's theory, e.g. Brans-Dicke theory. famous for being faithful to Mach's principle, scalar- and vector-tensor theories, etc. From the philosophical point of view, the most interesting is Whitehead's theory of relativity. This theory, originally published in 1922, has a different paradigm from Einstein's, elegant and simple in mathematical formulation with its own philosophical background. It has been called as "a thorn in Einstein's side", because it agrees with Einstein in its prediction for all the classical tests. Whitehead's theory is closely connected with his philosophy of nature and his metaphysics. We cannot understand it without paying due attention to his philosophy. Comparing it with Einstein's theory, we may summarize the main oppositions between them as follows:
( 1) Whitehead's theory does not presuppose "the principle of relativity" in Einstein's sense. It contains a subsystem which corresponds to Einstein's theory of special relativity, but it can do without "the principle of special relativity" and "the principle of the constant velocity of light." For example, it derives the Lorentz Transformation only in terms of the weak condition concerning the symmetry and uniformity of space-time. Moreover, "the principle of general relativity" does not hold in Whitehead's theory of gravitation, in which the inertial systems are not equivalent to the rotating systems of reference.
(2) Whitehead rejected "the principle of equivalence" which was the cornerstone of Einstein's theory oj'genera/ relativity. According to Whitehead, there is no reason why we should give privileged status to gravitational fields with respect to the space-time metric. They should be treated on a par with other physical fields. The gravitational and inertial forces are, therefore on principle, distinguished from each other in his theory.
(3) Whitehead did not adopt the deterministic world-view in his background cosmology. According to his philosophy of nature, natural laws only partially restrict future contingency. The concept of matter as the substance of nature disappears with his rejection both of Cartesian dualism and of Spinoza's monism. The concept of event, or of duration which is the field of creative becoming, plays the central role in his theory.
Thus we have to say that Whitehead's theory is different from Einstein's with respect both to the formal and to the material principles, in addition to the difference of world-views in the background.
I don't intend to decide by an outside criterion which theory is better, but to consider each in its own context. It is not easy for us to compare between theories with different paradigms, and the simple data cannot tell us crucial matters by themselves. What we want is the integration of the two paradigms. This does not mean that the problem of empirical tests might well be devalued. On the contrary, as long as we discuss physics, we must try to formulate theories in such a way that they are refutable by possible observation. The problem is that there exists a difference between them concerning the kind of principles that are subject to empirical refutation.
Whitehead once said of Einstein that "the worst homage we can pay to genius is to accept uncritically formulations of truths which we owe to it." This kind of critical spirit will become the guiding thread in the following consideration, with proviso that it should be the case with Whitehead as well.
What we must notice before discussing empirical tests is that Whitehead's principle of relativity has a different meaning from that of Einstein's. Taking into consideration the importance of the Whiteheadian relativity principle, we must first make clear what he means by it in the context of his own philosophy.
