Ernst Cassirer was a neo-Kantian philosopher who had a great influence on the philosophical implications of quantum physics, by personal contacts with the major quantum physicists, and through his 1936 book Determinism and Indeterminism in Modern Physics. The English translation, published in 1956, was prepared with the help of Henry Margenau, who had studied with Cassirer.
Max Born said it was a satisfaction to him that Cassirer “also sees the philosophical importance of quantum theory not so much in the question of indeterminism but in the possibility of several complementary perspectives in the description of the same phenomena as soon as different standpoints of meaning are taken.”
Arthur Stanley Eddington had associated free decisions with “free” electron jumps, a position he repudiated a few years after Cassirer’s book.
Cassirer attacked this simplistic notion:
When it is said that the electron is bound in no other way than as demanded by these rules, or that it has a certain playground within which it is “free,” this is nothing else and nothing more than a metaphysical mode of expression. From this interpretation of freedom as a mere possibility, bounded by natural laws, there is no path toward that reality of will and decision which concerns ethics. To identify the “selection” (Auswahl) that an electron is able to make from the set of different quantum orbits — in accordance with Bohr’s theory — with “choice” (Wahl) in the ethical sense of that concept would be to succumb to a purely linguistic confusion. For a choice exists only when there are not only different possibilities, but where also a conscious differentiation and a conscious decision is made.
Note that Cassirer is here very close to the idea of the two-stage Cogito model of free will, if he would accept the different possibilities as generated by quantum randomness.
But Cassirer strongly defends determinism (p.203), so doubts that quantum mechanics can help with the problem of free will:
The new mode of determination which is to be established is not built on the ruins of nature’s conformity to law; rather it joins the latter as a correlative and complement. For this reason alone it is most questionable whether, or in what manner, a relaxation or dissolution of scientific determinism can be made useful for the solution of the fundamental problem of ethics.
Cassirer is concerned about the randomness objection in the standard argument against free will
A “freedom” emanating from such a source and based on such a foundation would be a fatal gift to ethics. For it would contradict the characteristic and positive meaning of ethics; it would not leave room for that moral responsibility the possibility and necessity of which ethics aims to prove. Whenever something is “ascribed” to a person in the ethical sense, it presupposes, and is connected with, some type of prior determination on the part of that person. An action which should simply fall out of the causal nexus, which should take place at random without reasons, would stand entirely alone and could not be referred or ascribed to a persisting ethical subject.
Dogmatic fatalism is pre-determinism. Adequate determinism is a critically developed determinism
Only an action “grounded” in some way can be considered a responsible action, and the value ascribed to it depends on the type, on the quality of these grounds and not on their absence. Thus the question of free will cannot and must not be confused with the question of physical indeterminism. The free will whose establishment concerns ethics is incompatible with a dogmatic fatalism; but it is by no means incompatible with a critically conceived and developed determinism.
Henry Margenau on Ernst Cassirer
Margenau was a close colleague, perhaps more a disciple, of Ernst Cassirer and generally claimed to agree with Cassirer’s thoughts on causality and determinism. When Cassirer died, Margenau was preparing an appendix for the 1956 English translation of Determinism and Indeterminism in Modern Physics. The appendix (and a bibliography) was to bring the question of causality up to date as of 1956.
A dozen years later, Margenau was invited to give the Wimmer Lecture at St. Vincent College in Pennsylvania. His topic was Scientific Indeterminism and Human Freedom, and instead of holding to Cassirer’s view “that it would be fatal for ethics to tie itself to and, as it were, fling itself into the arms of a limitless indeterminism,” Margenau embraced indeterminism as the first step toward a solution of the problem of human freedom.
Margenau lamented that “it forces us to part company with many distinguished moral philosophers who see the autonomy of ethics threatened when a relation of any sort is assumed to exist between that august discipline and science.” He clearly means his longtime mentor. “Ethics,” says Cassirer, “should not be forced to build its nests in the gaps of physical causation, but he fails to tell where else it should build them, if at all.”
(Scientific Indeterminism and Human Freedom, Wimmer Lecture XX, 1968 (p.71))
Ernst Cassirer on Emil du Bois-Reymond
Cassirer devotes the opening pages of his Determinism and Indeterminism in Modern Physics to the claim that “determinism” in the modern sense of a complete causal physical determinism was not really understood until an essay of du Bois-Reymond in 1872.
This seems completely wrong, but Cassirer was very influential for many modern physicists, insisting on subjective versus objective views (mirroring Neils Bohr’s dualistic complementarity, with its wave versus particle views. Cassirer preserves a spiritual view, similar to Immanuel Kant’s noumenal world view, as the realm of ethics and freedom.
Du Bois-Reymond was quite wrong about determinism, which was equated with necessity in the eighteenth-century debates about freedom versus necessity. He is right that those debates turned into questions of freedom versus determinism in the nineteenth century, but they both assumed there were causal chains that threatened human freedom. See chapter 18 on “Cassirer’s Thesis” in Ian Hacking’s The Taming of Chance for more.