Human Freedom and the Limitations of Scientific Determinism

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Recent developments in science have stimulated the centuries-old debate between proponents of determinism and those who defend human freedom. Determinism implies that every event, including every human action, is causally necessitated by prior events, so that no person could have acted otherwise. If so, it would seem that free will is an illusion. It we could not have avoided acting as we did, it is pointless to hold people morally responsible for their acts. Man becomes merely an agglomeration of molecules in motion or a product of genetic evolution. Even mind and consciousness, under the determinist view, will ultimately be explained by the laws of inanimate matter. Because of the prestige of science, non-scientists arc inclined to assume that what scientists say about the natural world is likely to be true. The prestige accorded to science unci scientists is well deserved. Science, like all other human endeavors, nevertheless has its limitations. Some of these have been noted by the renowned physicist Stephen Hawking: "Godel's theorem, Heisenberg's uncertainty principle, and the practical impossibility of following the evolution of even a deterministic system that becomes chaotic, form a core set of limitations to scientific knowledge that only came to be appreciated during the twentieth century." (1) More broadly, it can be said that science ceases to be fully applicable whenever the question at issue depends on phenomena that cannot be measured or empirically observed and therefore cannot be reduced to quantitative analysis. Such common terms as "meaning," "beauty" and "justice" fall into this non-quantifiable category.

Standard definitions of freedom include at least four principal meanings: 1) the state of not being coerced or constrained by necessity or circumstances beyond one's control; 2) the absence of antecedent causal determination of human decisions; 3) exemption from slavery or involuntary restraint by others; and 4) political meanings: e.g., the right to speak, vote, or otherwise participate in public affairs. In this essay, we will be concerned primarily with the second meaning. The relevant question has been succinctly put by Steven Pinker: "...how can we have both explanation, with its requirement of lawful causation, and responsibility, with its requirement of free choice?" (2)

The debate over "free will" has been a staple of Western philosophy for centuries. Aristotle assumed as self-evident that freedom is a presupposition of moral action, since one incurs responsibility only for voluntary actions. (3) This assumption has been generally accepted by moral philosophers, since moral philosophy would make little sense without it. In Kant's moral writings, for example, morality presupposes freedom of the will: "the will of a rational being can be a will of its own only under the idea of freedom. ..." (4)

The rise of modern science, however, has led some observers to question the presumption of freedom. Many (perhaps most) scientists believe that science progresses through a process of reduction, in which the world is seen as an assemblage of physical parts that can be broken apart into their elementary constituents, whose behavior is or will eventually be explained entirely by the laws of physics. Determinism assumes that the state of the world at any instant of time, including our disposition to act, follows necessarily from the state of the world at the immediately preceding instant of time by reason of the laws of physical causation. The past completely determines the present. If determinism is true, such human feelings as resentment, blame, remorse, and forgiveness are pointless and human beings are objects to be manipulated rather than subjects of personal relationships. The deterministic point of view thus renders meaningless human dignity, human rights, and much of the discourse of customary human interaction. No one can deny, of course, that there are serious constraints on human freedom. …