Metaphysics - The Value of Metaphysics

The Value of Metaphysics

A number of individuals have suggested that much of metaphysics should be rejected. In the 18th century, David Hume took an extreme position, arguing that all genuine knowledge involves either mathematics or matters of fact and that metaphysics, which goes beyond these, is worthless. He concludes his Enquiry Concerning Human Understanding with the statement:

If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.

In the 1930s, A. J. Ayer and Rudolf Carnap endorsed Hume's position; Carnap quoted the passage above. They argued that metaphysical statements are neither true nor false but meaningless since, according to their verifiability theory of meaning, a statement is meaningful only if there can be empirical evidence for or against it. Thus, while Ayer rejected the monism of Spinoza, noted above, he avoided a commitment to pluralism, the contrary position, by holding both views to be without meaning. Carnap took a similar line with the controversy over the reality of the external world.

33 years after Hume's Enquiry appeared, Immanuel Kant published his Critique of Pure Reason. Though he followed Hume in rejecting much of previous metaphysics, he argued that there was still room for some synthetic a priori knowledge, concerned with matters of fact yet obtainable independent of experience. These included fundamental structures of space, time, and causality. He also argued for the freedom of the will and the existence of "things in themselves", the ultimate (but unknowable) objects of experience.

Much recent work has been devoted to analyzing the role of metaphysics in scientific theorizing. Alexandre Koyré led this movement, declaring in his book Metaphysics and Measurement, "It is not by following experiment, but by outstripping experiment, that the scientific mind makes progress." Imre Lakatos maintained that all scientific theories have a metaphysical "hard core" essential for the generation of hypotheses and theoretical assumptions. Thus, according to Lakatos, "scientific changes are connected with vast cataclysmic metaphysical revolutions."

An example from biology of Lakatos' thesis: David Hull has argued that changes in the ontological status of the species concept have been central in the development of biological thought from Aristotle through Cuvier, Lamarck, and Darwin. Darwin's ignorance of metaphysics made it more difficult for him to respond to his critics because he could not readily grasp the ways in which their underlying metaphysical views differed from his own.

In physics, new metaphysical ideas have arisen in connection with quantum mechanics, where subatomic particles arguably do not have the same sort of individuality as the particulars with which philosophy has traditionally been concerned. Also, adherence to a deterministic metaphysics in the face of the challenge posed by the quantum-mechanical uncertainty principle led physicists like Albert Einstein to propose alternative theories that retained determinism.

In chemistry, Gilbert Newton Lewis addressed the nature of motion, arguing that an electron should not be said to move when it has none of the properties of motion.

Katherine Hawley notes that the metaphysics even of a widely accepted scientific theory may be challenged if it can be argued that the metaphysical presuppositions of the theory make no contribution to its predictive success.