We have become quite familiar with the idea of an evolution of structures throughout the ascending types of animals. To a considerable degree we have become familiar with the thought that an evolution of functions has gone on pari passu with the evolution of structures. Now advancing a step, we have to frame a conception of the evolution of conduct, as correlated with this evolution of structures and functions. (§3 ¶1)

These three subjects are to be definitely distinguished. Obviously the facts comparative morphology sets forth, form a whole which, though it cannot be treated in general or in detail without taking into account facts belonging to comparative physiology, is essentially independent. No less clear is it that we may devote our attention exclusively to that progressive differentiation of functions, and combination of functions, which accompanies the development of structures—may say no more about the characters and connexions of organs than is implied in describing their separate and joint actions. And the subject of conduct lies outside the subject of functions, if not as far as this lies outside the subject of structures, still, far enough to make it substantially separate. For those functions which are already variously compounded to achieve what we regard as single bodily acts, are endlessly re-compounded to achieve that co-ordination of bodily acts which is known as conduct. (§3 ¶2)

We are concerned with functions in the true sense, while we think of them as processes carried on within the body; and, without exceeding the limits of physiology, we may treat of their adjusted combinations, so long as these are regarded as parts of the vital consensus. If we observe how the lungs aërate the blood which the heart sends to them; how heart and lungs together supply aërated blood to the stomach, and so enable it to do its work; how these co-operate with sundry secreting and excreting glands to further digestion and to remove waste matter; and how all of them join to keep the brain in a fit condition for carrying on those actions which indirectly conduce to maintenance of the life at large; we are dealing with functions. Even when considering how parts that act directly on the environment—legs, arms, wings—perform their duties, we are still concerned with functions in that aspect of them constituting physiology, so long as we restrict our attention to internal processes, and to internal combinations of them. But we enter on the subject of conduct when we begin to study such combinations among the actions of sensory and motor organs as are externally manifested. Suppose that instead of observing those contractions of muscles by which the optic axes are converged and the foci of the eyes adjusted (which is a portion of physiology), and that instead of observing the co-operation of other nerves, muscles, and bones, by which a hand is moved to a particular place and the fingers closed (which is also a portion of physiology), we observe a weapon being seized by a hand under guidance of the eyes. We now pass from the thought of combined internal functions to the thought of combined external motions. Doubtless if we could trace the cerebral processes which accompany these, we should find an inner physiological co-ordination corresponding with the outer co-ordination of actions. But this admission is consistent with the assertion, that when we ignore the internal combination and attend only to the external combination, we pass from a portion of physiology to a portion of conduct. For though it may be objected that the external combination instanced, is too simple to be rightly included under the name conduct, yet a moment’s thought shows that it is joined with what we call conduct by insensible gradations. Suppose the weapon seized is used to ward off a blow. Suppose a counterblow is given. Suppose the aggressor runs and is chased. Suppose there comes a struggle and a handing him over to the police. Suppose there follow the many and varied acts constituting a prosecution. Obviously the initial adjustment of an act to an end, inseparable from the rest, must be included with them under the same general head; and obviously from this initial simple adjustment, having intrinsically no moral character, we pass by degrees to the most complex adjustments and to those on which moral judgments are passed. (§3 ¶3)

Hence, excluding all internal co-ordinations, our subject here is the aggregate of all external co-ordinations; and this aggregate includes not only the simplest as well as the most complex performed by human beings, but also those performed by all inferior beings considered as less or more evolved. (§3 ¶4)

Already the question—What constitutes advance in the evolution of conduct, as we trace it up from the lowest types of living creatures to the highest? has been answered by implication. A few examples will now bring the answer into conspicuous relief. (§4 ¶1)

We saw that conduct is distinguished from the totality of actions by excluding purposeless actions; but during evolution this distinction arises by degrees. In the very lowest creatures most of the movements from moment to moment made, have not more recognizable aims than have the struggles of an epileptic. An infusorium swims randomly about, determined in its course not by a perceived object to be pursued or escaped, but, apparently, by varying stimuli in its medium; and its acts, unadjusted in any appreciable way to ends, lead it now into contact with some nutritive substance which it absorbs, and now into the neighbourhood of some creature by which it is swallowed and digested. Lacking those developed senses and motor powers which higher animals possess, ninety-nine in the hundred of these minute animals, severally living for but a few hours, disappear either by innutrition or by destruction. The conduct is constituted of actions so little adjusted to ends, that life continues only as long as the accidents of the environment are favourable. But when, among aquatic creatures, we observe one which, though still low in type, is much higher than the infusorium—say a rotifer—we see how, along with larger size, more developed structures, and greater power of combining functions, there goes an advance in conduct. We see how by its whirling cilia it sucks in as food these small animals moving around; how by its prehensile tail it fixes itself to some fit object; how by withdrawing its outer organs and contracting its body, it preserves itself from this or that injury from time to time threatened; and how thus, by better adjusting its own actions, it becomes less dependent on the actions going on around, and so preserves itself for a longer period. (§4 ¶2)

A superior sub-kingdom, as the Mollusca, still better exemplifies this contrast. When we compare a low mollusc, such as a floating ascidian, with a high mollusc, such as a cephalopod, we are again shown that greater organic evolution is accompanied by more evolved conduct. At the mercy of every marine creature large enough to swallow it, and drifted about by currents which may chance to keep it at sea or may chance to leave it fatally stranded, the ascidian displays but little adjustment of acts to ends in comparison with the cephalopod; which, now crawling over the beach, now exploring the rocky crevices, now swimming through the open water, now darting after a fish, now hiding itself from some larger animal in a cloud of ink, and using its suckered arms at one time for anchoring itself and at another for holding fast its prey; selects, and combines, and proportions, its movements from minute to minute, so as to evade dangers which threaten, while utilizing chances of food which offer: so showing us varied activities which, in achieving special ends, achieve the general end of securing continuance of the activities. (§4 ¶3)

Among vertebrate animals we similarly trace up, along with advance in structures and functions, this advance in conduct. A fish roaming about at hazard in search of something to eat, able to detect it by smell or sight only within short distances, and now and again rushing away in alarm on the approach of a bigger fish, makes adjustments of acts to ends that are relatively few and simple in their kinds; and shows us, as a consequence, how small is the average duration of life. So few survive to maturity that, to make up for destruction of unhatched young and small fry and half-grown individuals, a million ova have to be spawned by a cod-fish that two may reach the spawning age. Conversely, by a highly-evolved mammal, such as an elephant, those general actions performed in commoa with the fish are far better adjusted to their ends. By sight as well, probably, as by odour, it detects food at relatively great distances; and when, at intervals, there arises a need for escape, relatively-great speed is attained. But the chief difference arises from the addition of new sets of adjustments. We have combined actions which facilitate nutrition—the breaking off of succulent and fruit-bearing branches, the selecting of edible growths throughout a comparatively wide reach; and, in case of danger, safety can be achieved not by flight only, but, if necessary, by defence or attack: bringing into combined use tusks, trunk, and ponderous feet. Further, we see various subsidiary acts adjusted to subsidiary ends—now the going into a river for coolness, and using the trunk as a means of projecting water over the body; now the employment of a bough for sweeping away flies from the back; now the making of signal sounds to alarm the herd, and adapting the actions to such sounds when made by others. Evidently, the effect of this more highly-evolved conduct is to secure the balance of the organic actions throughout far longer periods. (§4 ¶4)

And now, on studying the doings of the highest of mammals, mankind, we not only find that the adjustments of acts to ends are both more numerous and better than among lower mammals; but we find the same thing on comparing the doings of higher races of men with those of lower races. If we take any one of the major ends achieved, we see greater completeness of achievement by civilized than by savage; and we also see an achievement of relatively numerous minor ends subserving major ends. Is it in nutrition? The food is obtained more regularly in response to appetite; it is far higher in quality; it is free from dirt; it is greater in variety; it is better prepared. Is it in warmth? The characters of the fabrics and forms of the articles used for clothing, and the adaptations of them to requirements from day to day and hour to hour, are much superior. Is it in dwellings? Between the shelter of boughs and grass which the lowest savage builds, and the mansion of the civilized man, the contrast in aspect is not more extreme than is the contrast in number and efficiency of the adjustments of acts to ends betrayed in their respective constructions. And when with the ordinary activities of the savage we compare the ordinary civilized activities—as the business of the trader, which involves multiplied and complex transactions extending over long periods, or as professional avocations, prepared for by elaborate studies and daily carried on in endlessly-varied forms, or as political discussions and agitations, directed now to the carrying of this measure and now to the defeating of that,—we see sets of adjustments of acts to ends, not only immensely exceeding those seen among lower races of men in variety and intricacy, but sets to which lower races of men present nothing analogous. And along with this greater elaboration of life produced by the pursuit of more numerous ends, there goes that increased duration of life which constitutes the supreme end. (§4 ¶5)

And here is suggested the need for supplementing this conception of evolving conduct. For besides being an improving adjustment of acts to ends, such as furthers prolongation of life, it is such as furthers increased amount of life. Reconsideration of the examples above given, will show that length of life is not by itself a measure of evolution of conduct; but that quantity of life must be taken into account. An oyster, adapted by its structure to the diffused food contained in the water it draws in, and shielded by its shell from nearly all dangers, may live longer than a cuttlefish, which has such superior powers of dealing with numerous contingencies; but then, the sum of vital activities during any given interval is far less in the oyster than in the cuttle-fish. So a worm, ordinarily sheltered from most enemies by the earth it burrows through, which also supplies a sufficiency of its poor food, may have greater longevity than many of its annulose relatives, the insects; but one of these during its existence as larva and imago, may experience a greater quantity of the changes which constitute life. Nor is it otherwise when we compare the more evolved with the less evolved among mankind. The difference between the average lengths of the lives of savage and civilized, is no true measure of the difference between the totalities of their two lives, considered as aggregates of thought, feeling, and action. Hence, estimating life by multiplying its length into its breadth, we must say that the augmentation of it which accompanies evolution of conduct, results from increase of both factors. The more multiplied and varied adjustments of acts to ends, by which the more developed creature from hour to hour fulfils more numerous requirements, severally add to the activities that are carried on abreast, and severally help to make greater the period through which such simultaneous activities endure. Each further evolution of conduct widens the aggregate of actions while conducing to elongation of it. (§4 ¶6)

Turn we now to a further aspect of the phenomena, separate from, but necessarily associated with, the last. Thus far we have considered only those adjustments of acts to ends which have for their final purpose complete individual life. Now we have to consider those adjustments which have for their final purpose the life of the species. (§5 ¶1)

Self-preservation in each generation has all along depended on the preservation of offspring by preceding generations. And in proportion as evolution of the conduct subserving individual life is high, implying high organization, there must previously have been a highly-evolved conduct subserving nurture of the young. Throughout the ascending grades of the animal kingdom, this second kind of conduct presents stages of advance like those which we have observed in the first. Low down, where structures and functions are little developed, and the power of adjusting acts to ends but slight, there is no conduct, properly so named, furthering salvation of the species. Race-maintaining conduct, like self-maintaining conduct, arises gradually out of that which cannot be called conduct: adjusted actions are preceded by unadjusted ones. Protozoa spontaneously divide and sub-divide, in consequence of physical changes over which they have no control; or, at other times, after a period of quiescence, break up into minute portions which severally grow into new individuals. In neither case can conduct be alleged. Higher up, the process is that of ripening, at intervals, germ-cells and sperm-cells, which, on occasion, are sent forth into the surrounding water and left to their fate: perhaps one in ten thousand surviving to maturity. Here, again, we see only development and dispersion going on apart from parental care. Types above these, as fish which choose fit places in which to deposit their ova, or as the higher crustaceans which carry masses of ova about until they are hatched, exhibit adjustments of acts to ends which we may properly call conduct; though it is of the simplest kind. Where, as among certain fish, the male keeps guard over the eggs, driving away intruders, there is an additional adjustment of acts to ends; and the applicability of the name conduct is more decided. Passing at once to creatures far superior, such as birds which, building nests and sitting on their eggs, feed their broods for considerable periods, and give them aid after they can fly; or such as mammals which, suckling their young for a time continue afterwards to bring them food or protect them while they feed, until they reach ages at which they can provide for themselves; we are shown how this conduct which furthers race-maintenance evolves hand-in-hand with the conduct which furthers self-maintenance. That better organization which makes possible the last, makes possible the first also. Mankind exhibit a great progress of like nature. Compared with brutes, the savage, higher in his self-maintaining conduct, is higher too in his race-maintaining conduct. A larger number of the wants of offspring are provided for; and parental care, enduring longer, extends to the disciplining of offspring in arts and habits which fit them for their conditions of existence. Conduct of this order, equally with conduct of the first order, we see becoming evolved in a still greater degree as we ascend from savage to civilized. The adjustments of acts to ends in the rearing of children become far more elaborate, alike in number of ends met, variety of means used, and efficiency of their adaptations; and the aid and oversight are continued throughout a much greater part of early life. (§5 ¶2)

In tracing up the evolution of conduct, so that we may frame a true conception of conduct in general, we have thus to recognize these two kinds as mutually dependent. Speaking generally, neither can evolve without evolution of the other; and the highest evolutions of the two must be reached simultaneously. (§5 ¶3)

To conclude, however, that on reaching a perfect adjustment of acts to ends subserving individual life and the rearing of offspring, the evolution of conduct becomes complete, is to conclude erroneously. Or rather, I should say, it is an error to suppose that either of these kinds of conduct can assume its highest form, without its highest form being assumed by a third kind of conduct yet to be named. (§6 ¶1)

The multitudinous creatures of all kinds which fill the Earth, cannot live wholly apart from one another, but are more or less in presence of one another—are interfered with by one another. In large measure the adjustments of acts to ends which we have been considering, are components of that struggle for existence carried on both between members of the same species and between members of different species; and, very generally, a successful adjustment made by one creature involves an unsuccessful adjustment made by another creature, either of the same kind or of a different kind. That the carnivore may live herbivores must die; and that its young may be reared the young of weaker creatures must be orphaned. Maintenance of the hawk and its brood involves the deaths of many small birds; and that small birds may multiply, their progeny must be fed with innumerable sacrificed worms and larvae. Competition among members of the same species has allied, though less conspicuous, results. The stronger often carries off by force the prey which the weaker has caught. Monopolizing certain hunting grounds, the more ferocious drive others of their kind into less favourable places. With plant-eating animals, too, the like holds: the better food is secured by the more vigorous individuals, while the less vigorous and worse fed, succumb either directly from innutrition or indirectly from resulting inability to escape enemies. That is to say, among creatures whose lives are carried on antagonistically, each of the two kinds of conduct delineated above, must remain imperfectly evolved. Even in such few kinds of them as have little to fear from enemies or competitors, as lions or tigers, there is still inevitable failure in the adjustments of acts to ends towards the close of life. Death by starvation from inability to catch prey, shows a falling short of conduct from its ideal. (§6 ¶2)

This imperfectly-evolved conduct introduces us by antithesis to conduct that is perfectly evolved. Contemplating these adjustments of acts to ends which miss completeness because they cannot be made by one creature without other creatures being prevented from making them, raises the thought of adjustments such that each creature may make them without preventing them from being made by other creatures. That the highest form of conduct must be so distinguished, is an inevitable implication; for while the form of conduct is such that adjustments of acts to ends by some necessitate non-adjustments by others, there remains room for modifications which bring conduct into a form avoiding this, and so making the totality of life greater. (§6 ¶3)

From the abstract let us pass to the concrete. Recognizing men as the beings whose conduct is most evolved, let us ask under what conditions their conduct, in all three aspects of its evolution, reaches its limit. Clearly while the lives led are entirely predatory, as those of savages, the adjustments of acts to ends fall short of this highest form of conduct in every way. Individual life, ill carried on from hour to hour, is prematurely cut short; the fostering of offspring often fails, and is incomplete when it does not fail; and in so far as the ends of self-maintenance and race-maintenance are met, they are met by destruction of other beings, of different kind or of like kind. In social groups formed by compounding and re-compounding primitive hordes, conduct remains imperfectly evolved in proportion as there continue antagonisms between the groups and antagonisms between members of the same group—two traits necessarily associated; since the nature which prompts international aggression prompts aggression of individuals on one another. Hence the limit of evolution can be reached by conduct only in permanently peaceful societies. That perfect adjustment of acts to ends in maintaining individual llfe and rearing new individuals, which is effected by each without hindering others from effecting like perfect adjustments, is, in its very definition, shown to constitute a kind of conduct that can be approached only as war decreases and dies out. (§6 ¶4)

A gap in this outline must now be filled up. There remains a further advance not yet even hinted. For beyond so behaving that each achieves his ends without preventing others from achieving their ends, the members of a society may give mutual help in the achievement of ends. And if, either indirectly by industrial co-operation, or directly by volunteered aid, fellow citizens can make easier for one another the adjustments of acts to ends, then their conduct assumes a still higher phase of evolution; since whatever facilitates the making of adjustments by each, increases the totality of the adjustments made, and serves to render the lives of all more complete. (§6 ¶5)

The reader who recalls certain passages in First Principles, in the Principles of Biology, and in the Principles of Psychology, will perceive above a re-statement, in another form, of generalizations set forth in those works. Especially will he be reminded of the proposition that Life is the definite combination of heterogeneous changes, both simultaneous and successive, in correspondence with external coexistences and sequences; and still more of that abridged and less specific formula, in which Life is said to be the continuous adjustment of internal relations to external relations. (§7 ¶1)

The presentation of the facts here made, differs from the presentations before made, mainly by ignoring the inner part of the correspondence and attending exclusively to that outer part constituted of visible actions. But the two are in harmony; and the reader who wishes further to prepare himself for dealing with our present topic from the evolution point of view, may advantageously join to the foregoing more special aspect of the phenomena, the more general aspects before delineated. (§7 ¶2)

After this passing remark, I recur to the main proposition set forth in these two chapters, which has, I think, been fully justified. Guided by the truth that as the conduct with which Ethics deals is part of conduct at large, conduct at large must be generally understood before this part can be specially understood; and guided by the further truth that to understand conduct at large we must understand the evolution of conduct; we have been led to see that Ethics has for its subject-matter, that form which universal conduct assumes during the last stages of its evolution. We have also concluded that these last stages in the evolution of conduct are those displayed by the highest type of being, when he is forced, by increase of numbers, to live more and more in presence of his fellows. And there has followed the corollary that conduct gains ethical sanction in proportion as the activities, becoming less and less militant and more and more industrial, are such as do not necessitate mutual injury or hindrance, but consist with, and are furthered by, co-operation and mutual aid. (§7 ¶3)

These implications of the Evolution-Hypothesis, we shall now see harmonize with the leading moral ideas men have otherwise reached. (§7 ¶4)