The Physical Basis of Life by Thomas Henry Huxley

First published: Written in 1868; published in Method and Results, 1896

Type of work: Essay in scientific philosophy

Critical Evaluation:

“The Physical Basis of Life,” together with the other essays that compose Huxley’s METHOD AND RESULTS, reveals a nineteenth-century man of science attempting to go beyond the limits prescribed by authoritarian scientists and churchmen and making an effort to bring the clarity of philosophy to the interpretation and expression of the results of empirical observation. This particular essay is among Huxley’s most famous. Its subject matter is protoplasm, and its claim is that all life has as its physical basis protoplasmic substance.

Such a claim, which to twentieth-century man seems so trivial as not to be worth making, was revolutionary in an age which demanded that all studies of man find him unique, possessed of a life-giving principle by reference to which he could be distinguished from all those animals that were merely animals. Huxley realized that his contention would be novel, even shocking, to many of his contemporaries. It was bad enough to suggest that life is not independent of matter but has a physical basis; it was even worse to insist that there is but one physical basis of life for all living things. To reduce man to the material and to equate him with the beast—that was intolerable even to those who respected science.

In his essay Huxley was careful to state that even though all life has protoplasm as its physical basis, it by no means follows that materialism—the philosophical theory that everything is nothing but matter—is true; in fact, he argued that materialism involved “grave philosophical error.”

Huxley’s objections to a strict materialism are made in the spirit of Hume’s philosophy. Referring to Hume as “the most acute thinker of the eighteenth century,” Huxley argues that we mean by the terms “matter” and “spirit” either something that can be explained by reference to matters of our scientific experience, or else names for unknown, even imaginary, causes. He joins Hume in objecting to the idea that it makes sense to talk about a necessity that is anything more than the observed order of events. “Fact I know; and Law I know,” wrote Huxley, “but what is this Necessity, save an empty shadow of my own mind’s throwing?” Since both materialism and spiritualism (or idealism) depend on unfathomable senses of the terms “matter,” “spirit,” and “necessity,” Huxley concluded that such unscientific philosophies were unsatisfactory.

In opposition to metaphysical philosophies, Huxley proposed what he called the “New Philosophy,” the attempt to limit philosophical thought and inquiry to matters that could be verified experimentally or explained by reference to matters of experience. In doing this he anticipated the most significant direction of twentieth-century philosophy, the logical empiricist movement as amended by pragmatism and linguistic analysis.

Huxley made a plea for limiting the consideration of problems to those matters about which something can be known. Agreeing with Hume in the rejection of theology and metaphysics, he argued that progress in scientific philosophy is possible on the basis of two assumptions: “the first, that the order of Nature is ascertainable by our faculties to an extent which is practically unlimited; the second, that our volition counts for something as a condition of the course of events.” In a footnote Huxley explained that it would be more accurate to say that not volition but “the physical state of which volition is the expression” may condition the course of events.

He then went on to point out the practical advantages, from the scientific point of view, that resulted from using the language of materialism. The materialistic terminology allowed the scientist to relate thought and life to experienceable phenomena and permitted a kind of expression which facilitated the human control of events. The language of those who held that all is spirit and idea—the spiritualists—was barren and confusing, according to Huxley.

Nevertheless, despite the practical advantages of the terminology of materialism, it would be a mistake, Huxley wrote, to slide into metaphysical materialism.

The reader who asks what Huxley was, if he was neither a materialist nor an idealist, makes the mistake of supposing that Huxley’s rejection of two opposing metaphysical positions is somehow a sign of his having adopted a third. The truth is that Huxley had no sympathy for metaphysics. He wanted to use an empirically meaningful language to talk about events that came within the scope of scientific inquiry; hence he had no metaphysics.

In arguing that protoplasm is the physical basis of life, Huxley was making a much more radical claim than the theory that without protoplasm there is no life. He argued that the matter of life is composed of ordinary matter; life is not an indestructible and unchangeable substance. Furthermore, the vital properties of protoplasm are the result of molecular changes. He concluded that his thoughts, and the thoughts of the audience, were the expression of molecular changes in protoplasm.

In his analysis Huxley found a unity in three respects among all living organisms: “a unity of power or faculty, a unity of form, and a unity of substantial composition.” The faculty which all living matter has in common is contractility; as to form, protoplasm is usually a nucleated mass, and it is composed of carbon, hydrogen, oxygen, and nitrogen. The line between plants and animals is not at all precise—there are borderline cases—but both forms of living matter are alike in the respects mentioned.

The essays collected under the title METHOD AND RESULTS, also to be found in Huxley’s COLLECTED ESSAYS (1898), are intended to outline “the indispensable conditions of scientific assent” as defined by Descartes in his DISCOURSE ON METHOD, and to show the results of applying the method to various problems. In an essay written in 1870 concerning Descartes’ method, Huxley praised Descartes as the thinker from whose works the philosophy and science of the modern world stem. Huxley agreed with Descartes in valuing doubt as the first critical operation in science and philosophy, as the beginning of what Goethe called “the active scepticism whose whole aim is to conquer itself.” Although he found fault with Descartes’ acceptance of “I think; therefore, I am” as an indubitable truth, he credited the Frenchman with having made a reconciliation of physics and metaphysics possible. According to Huxley, Descartes’ analysis suggests what physics must admit: that “all the phaenomena of Nature are, in their ultimate analysis, known to us only as facts of consciousness. . . .” But metaphysics must admit, Huxley adds, that the facts of consciousness make sense, practically speaking, only as interpreted by physics. The ideas in this essay are very similar to those which William James was later (1906-1907) to present as the basis of pragmatism in his lectures at Columbia University.

Devotion to skepticism and to the benefits of natural science was shown and defended by Huxley in his essay “On the Advisableness of Improving Natural Knowledge” (1866). The essay is a defense of the advantage of finding out about the world by studying the world itself, a sensible procedure from the twentieth-century point of view. But the tentative, practical, empirical character of natural science was believed by many critics of Huxley to be antipathetic to religion. Huxley himself argued that science need not conflict with religion, although it could not tolerate meaningless metaphysics and theology. Huxley concluded that science must refuse to acknowledge authority; for the scientist “scepticism is the highest of duties; blind faith the one unpardonable sin.” Justification for the scientist is not by faith, but by verification.

These ideas led Huxley to argue bitterly against churchmen who proclaimed that belief in God or in the particular dogmas of a church was the duty of every man. The duty of a man, according to Huxley, is to face the facts, to test his ideas by reference to the course of natural events, and to know the limits of his inquiry. It cannot be his duty, then, to believe what he has no reason to believe.

Almost a century after Huxley wrote “The Physical Basis of Life,” it seems clear that the value of the essay results from the clear and temperate defense of scientific method which it contains. Resisting the impulse to deify science, Huxley indicated its method and results; and he rested secure in the conviction that the progress of science would justify his faith. There is every reason to suppose that from Huxley’s point of view, that of a man concerned with the practical search for knowledge, he was right in his belief.