The Difference Between Life and Non-Life

a) How Things May Differ — b) Points of Essential Difference in Living and Lifeless Bodies

a) How Things May Differ

Things are either identical or they are different. The identity of things may be more or less complete. It may occur only in minor matters such as quality or quantity (thus snow and milk are identical in point of whiteness; honey and sugar are identical in the fact that they are both sweet; a yard of silk is identical with a yard of cotton in quantity) or it may occur in the major matter of essence. In point of essence again, identity may be more or less complete. The oak and the pine are identical as trees; the oak, the pine, weeds, moss, grass, and ivy are not identical as trees, but they are identical as plants.

The absence of identity is called distinction, and sometimes difference. It is obvious that just as identity is a matter of degree, so with difference.

Of course, every single reality in the universe has its own proper identity as an individual thing, and, in this respect, it is distinct and different from every other individual thing. The grains of sugar in a sugar-basin are individual grains; one is not another; and hence every grain is distinct from (and, in so far, different from) every other grain, and from every other reality. But the grains of sugar are all of the same essential kind; they are identical in their essence, even though they are distinct as individual grains. Again: John and Mary differ as individuals; they differ in sex and in name, and, most likely, in age, in size, in weight, in appearance, in complexion, in strength of body, in ability of mind, in disposition, in degree of health; likely, they differ also in parentage and place of birth; perhaps they differ in nationality, and even in color. But John and Mary do not differ in their essence,—in the basic kind of being they are; for each is a human being. They differ as individuals, but not in essential kind. In other words, their difference is not essential, but non-essential or accidental.

Now we ask about the difference between life and non-life, which, for our present study, amounts to the difference between living bodies and lifeless bodies. We ask, “Is this difference essential, or is it merely accidental?” The question is fundamental in psychology; upon its answer depends our whole philosophy of life and living bodies. And the right answer to the question is this: living bodies differ essentially from non-living bodies. The proof of this assertion is now to follow.

b) Points of Essential Difference Between Living and Lifeless Bodies

Everyone knows that there are marked differences between living bodies and lifeless bodies. But some philosophers and scientists have taught that these differences are not essential but merely accidental. Against this mistaken view stands the certain fact that the properties of a thing (unvarying characteristics and inevitable functions) indicate its essence; and the fact that the properties of living bodies are essentially different from (and often opposite to) the properties of non-living bodies. Now, essences that are indicated by essentially different properties are essentially different essences. Therefore, living bodies are essentially different from non-living bodies.

Among many points of essential difference between living and lifeless bodies we must notice the following:

1. Natural Origin—Living bodies come into existence by way of vital generation. Immediately or mediately, parent bodies produce them. And the parent bodies are of the same essence and nature as the generated bodies. Non-living bodies do not come into existence in this way. They are not generated by a vital process but are formed by physical accretion or by chemical combination. The apple-tree produces apples which have seeds that will produce other apple-trees, and these will produce other apples, and so on indefinitely. Apple-trees really come from parent apple-trees (in the mediate way described above, or by the immediate way of cutting and planting a suitable portion of the parent tree). The parent-trees and the generated trees are of the same nature and essence. But a block of granite does not bud forth fruit or seeds from which other blocks of granite may be grown, nor will a “cutting” of the block grow and develop into another block. In point of natural origin we discern an essential difference between living and lifeless bodies.

2. Growth and Decline—A living body begins with a cell or group of cells which multiply and form tissues and organs and so build up a definite and complete living body (or organism) of a determinate type and kind. Normally, this body will develop into a state of maturity, using, from the first,—as indeed it did in its primal cells,—a strange power called nutrition, by which it takes alien substances into itself and changes these into its own substance. Reaching maturity, the living body tends to maintain its perfection for a time, still taking food and replacing the cells and tissues used up in the exercise of its functions. After a time,—even though food remain plentiful and all external conditions for living continue favorable,—the living body begins to decline in power, activity, function. Presently the organism breaks down; life is no longer present; the body is resolved into its physical and chemical elements. Now, it is not so with the growth and decline of non-living bodies. These do not really grow at all, even when they increase in size or bulk. Non-living bodies do not come from active cells which multiply to build up their bulk and structure. There is, in lifeless bodies, no inner drive for development to a state of maturity or towards completeness in size, shape, or constitution. Lifeless bodies increase by the addition of parts from without, not by the development of parts through the exercise of immanent power. No one can fail to notice the essential difference between the growth of a plant and the increase of a snowdrift. The plant grows by the exercise of an inner power which assimilates alien substances and changes these into its own substance; the snowdrift grows by the external addition of flake to flake. Like the snowdrift, certain crystalline substances “grow”; chemical attraction draws to the mass of crystals other free crystals of the same essential kind, and these are piled up, layer on layer, to make the mass larger. But who does not see that this is a process essentially different from the growth of a living body?—Living bodies tend to exist and function for a period of time which can be well determined within maximum and minimum limits, and then to break down and decay; they tend to run a definite course of self-perfective action. Non-living bodies, on the contrary, tend to remain stable and maintain an equilibrium. The crystal vase may be as frail as the lily it contains; but the vase, if merely left alone, will stand ten thousand years, while the lily fades, dies, and falls to pieces in a few hours. Non-living bodies may, indeed, be worn down and dissolved, but this is always an effect of the activity of outer agencies; they never disappear through the failure of some indwelling power which finds the body structure increasingly unsuitable to sustain its action. It is surely obvious that, in point of growth and decline, living and lifeless bodies are marked by essential differences.

3. Structure and Function—Every living body is cellular in structure. That is to say, a living body is made up of cells, which are microscopic bits of living matter (and hence each cell is itself a living body). The cells are highly complex in constitution and amazingly active. They grow and divide, spread and multiply, to build up a body of most varied parts (roots, bark, fiber, leaves, etc., or flesh, bone, muscle, nerve, etc.) and yet a body that is perfectly arranged and organized according to a definite type, and unified for its proper functions. The cells build up the body and the organs of the body. Organs are special parts (root, radicel, sucker, etc., or eye, ear, nose, lung, liver, heart, etc.) which are fitted to different and individual functions, and yet all their varied operations are meant to serve the living body as a whole. The cells thus build up a body that is most complex and varied in its parts, and all the various parts come together in a marvellous unity and balance according to a definite nature, plan, and type, in each sort of living body. The living body is, therefore, heterogeneous in its parts (that is, it has parts of different kinds) but perfectly harmonious in its entirety. The union of heterogeneous parts in a harmonious living unit is called organization (for each part is an organ) and the living body is said to be organized and constitutes an organism. Sometimes we use these terms metaphorically in our daily speech, as when we speak of a newspaper as the organ of a political party, or say that a committee was organized for some purpose, or declare that a company of business men is a well-balanced organization. But, strictly and literally, there is no organization but that of the parts of a living body united in one harmonious whole. The word organism is synonymous with living body. Every living cell is an organism (for it is a living unit made of various parts) and every body made of living cells is an organism.—Now, non-living bodies are not cellular in structure, nor are they built up by a drive or power resident in their elements and tending to form them into bodies of definite structure and function. Atoms and molecules are active in non-living bodies, but their activity is purely mechanical (local movement), physical (variation in qualities, such as color, heat, sound, electricity), and chemical (activity of uniting, dissolving, etc.); their activity is never vital. In other words, the activities of non-living bodies are invariably transient in character, while the activities of organisms (that is, of living bodies) are specifically immanent. Of course, living bodies are bodies and have the activities proper to all bodies, living and lifeless; and hence there is much activity, even in organisms, which is mechanical, physical, or chemical in character. But the point we make is this: living bodies have all the kinds of activity observable in non-living bodies, and, in addition, they possess an inner drive towards definite, complex, balanced structure and function, which non-living bodies do not possess at all, and do not so much as begin to possess at all. Further: living bodies are heterogeneous in their parts; lifeless bodies are homogeneous (that is, all parts are the same essential kind). The branch of a tree is of a different structure from its root; the fruit is not the same as the bark; but a bit of limestone chipped from a block is of the same structure as the block. An explosion may blow plant or animal into ten thousand pieces; but the pieces are not as perfectly plants or animals as the original living body was plant or animal. But an explosion will blow a block of limestone into ten thousand pieces, and each of the pieces is just as perfectly limestone as the original block. This illustrates what we mean by indicating heterogeneity and homogeneity as points of essential difference between living and lifeless bodies. We might develop the point further: the parts of a heterogeneous living organism are interdependent; their special functions all meet in a unified and unvarying tendency to perfect the organism as a whole,—to develop it, preserve it, and propagate it. And these interdependent parts and functions are thus substantially united in one living body. But the parts of a homogeneous mass (non-living body) are not interdependent, and they cling together accidentally (and not substantially) by reason of the external or extrinsic forces called gravitation and cohesion. Knock off a part from a living body, and the body suffers; it tends to repair the injury, and if it cannot repair it, or heal its wound and manage without the lost part, it dies and decays, and is dissolved into non-living matter. Knock off a part from a non-living body (a stone, a block of dry wood, a ball of wax) and the body is not discomfited; it makes no effort to heal or repair; it shows no tendency to decay and to resolve itself into other kinds of matter. Here we see that in point of interdependence and substantial union of parts, living bodies differ essentially from non-living bodies, the parts of which are not interdependent nor substantially unified. In all this we clearly see that living and lifeless bodies are such different things that only the blindest or most perverse judgment could refuse to recognize their difference as essential. Structure and function indicate, beyond the possibility of quibble, that living and non-living bodies are basically different kinds of bodies. In other words, they are essentially different.

Summary of the Article

In this Article we have studied the meaning of identity and difference, and have learned what is meant by essential difference as distinguished from accidental difference. We have reasoned from the essential difference of the properties of living and of lifeless bodies to the essential difference of these bodies themselves. In support of our reasoned argument we have drawn special proofs from a study of living and non-living bodies in point of their natural origin, their growth and decline, and their structure and function. Thus we have established the inescapable truth that between life and non-life, between living bodies and lifeless bodies, there is a difference truly essential.