人禽之別幾希？

人類獨特的心靈？St. George Jackson Mivart: non-human animals might have bodies similar to ours, but our minds remain something special.

“There is no fundamental difference between man and the higher mammals in their mental faculties.” (Darwin)

The pattern of Darwin’s argument

First, he gives a large number of examples of animal behavior, designed to overwhelm the reader with evidence that animals do in fact have instincts that operate for the good of the community.

Then he argues that this not surprising, but is precisely what one would expect on the hypothesis of natural selection. Along the way he protests the inconsistency of our unwillingness to attribute morality to the animals, when we would so characterize men for essentially the same behavior.

And finally, he offers an account of how the distinctive features of human morality could have evolved from non-human beginnings.

理性能力“Of all the faculties of the human mind, it will, I presume, be admitted that Reason stands at the summit. Few persons any longer dispute that animals possess some power of reasoning. Animals may constantly be seen to pause, deliberate, and resolve. It is a significant fact, that the more the habits of any particular animal are studied by the naturalist, the more he attributes to reason and the less to unlearnt instincts.”

“So many facts have been recorded in various works showing that animals possess some degree of reason, that I will here give only two or three instances, authenticated by Rengger, and relating to American monkeys, which stand low in their order. He states that when he first gave eggs to his monkeys, they smashed them and thus lost much of their contents; afterwards they gently hit one end against some hard body, and picked off the bits of shell with their fingers. After cutting themselves only once with any sharp tool, they would not touch it again, or would handle it with the greatest care. Lumps of sugar were often given to them wrapped up in paper; and Rengger sometimes put a live wasp in the paper, so that in hastily unfolding it they got stung; after this had once happened, they always first held the packet to their ears to detect any movement within. Anyone who is not convinced by such facts as these, and by what he may observe with his own dogs, that animals can reason, would not be convinced by anything I could add.”

人禽之別：moral sense

“Of all the differences between man and the lower animals, the moral sense is by far the most important.”

Darwin: non-human animals have the same capacities that form the basis of morality in humans; although in non-humans those capacities are not so well developed.

Social Instincts

Evidence of sociability in animals: their living in groups and their apparent need for one another’s company.

“Everyone must have noticed how miserable horses, dogs, sheep, etc. are when separated form their companions; and what affection at least the two former kinds show on their reunion.”

“Social animals perform many little services for each other: horses nibble, and cows lick each other, on any spot which itches: monkeys search for each other’s external parasites.”

Social instincts (不求回報的利他行為 )

“Capt. Stansbury found on a salt lake in Utah an old and completely blind pelican, which was very fat, and must have been long and well fed by his companions. Mr. Byth, as he informs me, saw Indian crows feeding two or three of their companions which were blind.”

Social instincts (不求回報的利他行為 )

“Brehm encountered in Abyssinia a great troop of baboons which were crossing a valley: some had already ascended the opposite mountain, and some were still in the valley; the latter were attacked by the dogs, but the old males immediately hurried down from the rocks, and with mouths widely opened, roared so fearfully, that the dogs quickly drew back. They were again encouraged to the attack; but by this time all the baboons had reascended the heights, excepting a young one, about six months old, who, loudly calling for aid, climbed on a block of rock, and was surrounded. Now one of the largest males, a true hero, came down again from the mountain, slowly went to the young one, coaxed him, and triumphantly led him away—the dogs being too much astonished to make an attack.”

Altruism in Rhesus Monkeys

Altruism might be defined simply as action that is motivated by the desire to help others. However, we may also use the word in a somewhat stronger sense, as involving the willingness to forgo some good for oneself in order to help others.

Understood in this stronger way, altruism is often taken to be the paradigmatic moral trait. But is altruism, in this sense, exclusively a human characteristic? Or do other animals also possess this quality?

A series of experiments conducted at the Northwestern University Medical School and reported in the psychological journals for 1964: these experiments were designed to discover whether rhesus monkeys are altruistic, and the method was to see whether they would be deterred from operating a device for securing food if doing so would cause pain to another monkey.

One animal (called by the experimenters the “operator” or “O”) was placed in one side of a divided box and taught to obtain food by pulling either of two chains. Food was available only when a light signal was given (a different light for each chain), and the O was trained to show no special preference for either chain.

Another monkey (called the “stimulus animal” or “SA”) was put into the other side of the box, which was divided by a one-way mirror so that the O could see the SA but not the other way around. The floor on the SA’s side was covered with a grid attached to a shock source. Three days were allowed for the O to adapt to the presence of the SA, and then a circuit was completed so that whenever the O pulled one of the chains to secure food the SA received a severe electrical shock. Pulling the other chain continued to give food, but produced no shock. Now, by turning on one signal light at a time, in various sequences and at various intervals, the experimenters could determine the extent to which the perception of the SA’s distress would influence the O’s willingness to pull the shock-producing chain.

After numerous trials the experimenters concluded that “a majority of rhesus monkeys will consistently suffer hunger rather than secure food at the expense of electroshock to a conspecific”. In particular, in one series of tests, 6 of 8 animals showed this type of sacrificial behavior; in a second series, 6 of 10; and in a third, 13 of 15. One of the monkeys refrained from pulling either chain for 12 days, and another for 5 days, after witnessing shock to the SA—which means they had no food at all during that time.

These experiments seem to show the rhesus monkeys are altruistic in the strong sense—that they will sacrifice their own good for the sake of others.

Some worries

Was the O’s reluctance to pull the shock chain correlated with relative positions in a dominance—submissiveness hierarchy?

Did differences in sex have any effect?

Reply to worry 1

Relative dominance was determined when the animals “were paired against each other in another apparatus and required to compete for 100 grapes presented one at a time. In most cases dominance was quickly established, the dominant animal getting 90 percent of the grapes.”

The experiments were then divided into those in which the dominant animal was the SA and the submissive animal was the O; those in which the roles were reversed; and so forth.

And it was found that this made no difference to the outcome.

Reply to worry 2

Experiments showed it made no difference whether the O was male and the SA female; whether they were both male; and so forth.

Additional evidence for the ascription of altruism

The experimenters found that animals who had previously been SAs were significantly more reluctant to pull the shock chain when they were made Os than animals who had not been SAs themselves.

The explanation suggested by the hypothesis of altruism is that these animals were more reluctant to pull the chain because, having suffered the shocks themselves, they had a more vivid comprehension of what it was like, and so a greater reluctance to see someone else in the same position.

Additional evidence for the ascription of altruism

It was also found that Os who had been cage-mates of their SAs were more reluctant to pull the shock chain than Os who had not been cage-mates of their SAs.

Again, this is just what we would expect if we take our common knowledge of human beings as our model: we are less willing to harm someone we know than we are to harm strangers.

Special moral capacities of human beings

Despite his concern to demonstrate continuities between human and animal life, Darwin does not argue that non-humans are moral agents in the same sense as humans: there are obviously differences between the moral capacities of humans and non-humans, and Darwin does not deny it. Instead, he sets himself to explain what those differences are and why they exist.

Darwin’s notion of morality

Darwin: when ethics is viewed from the perspective of natural history, we find reason to reject the opinion of some philosophers that “the foundation of morality lay in a form of selfishness.” It is the social instinct, and not the instinct for self-preservation, that forms its basis.

Therefore, Darwin says, those philosophers who have advocated “the Greatest Happiness principle” are closer to the mark—although he thinks it would be better to speak of “the general good or welfare of the community, rather than the general happiness.” (The latter, in his opinion, is too restricted a term.) Of course, Darwin believed that the social instincts arise only because the drive for self-preservation is more fundamental. But morality comes into existence only with the social instincts. Hence Darwin’s insistence that “the Greatest Happiness principle” more aptly expresses the basic moral rule.

Darwin’s notion of morality

Darwin assumes that moral behavior promotes the general welfare, but he also stresses that a moral agent is an individual with a conscience—a sense of duty—not unlike that envisioned by Kant.

The two notions are wedded by Darwin’s assumption that a person of conscience will standardly approve of behavior that promotes the general welfare.

The task he sets himself is to explain, compatibly with the principles of natural selection, how humans could have come to be moral agents of this sort.

Reason and the acquisition of moral knowledge

Human morality is the product, not just of the social instincts, but of the the social instincts plus intelligence.

Thus, on Darwin’s view, the higher stages of morality emerge with the development of the higher rational capacities: “Any animal whatever, endowed with well-marked social instincts, would inevitably acquire a moral sense or conscience, as soon as its intellectual powers had become as well developed, or nearly we well developed, as in man.”

智力如何促進道德？“The social instincts which no doubt were acquired by man, as by the lower animals, for the good of the community, will from the first have given to him some wish to aid his fellows, and some feeling of sympathy. Such impulses will have served him at a very early period as a rude rule of right and wrong. But as man gradually advanced in intellectual power and was enabled to trace the more remote consequences of his actions; as he acquired sufficient knowledge to reject baneful customs and superstitions…so would the standard of his morality rise higher and higher.”

Conscience

18th century Britain produced a distinguished group of moral philosophers, including such figures as Lord Shaftesbury, Joseph Butler, and David Hume. The idea of a “moral sense”, or conscience, was prominent in their thinking, but they gave the notion a decidedly naturalistic interpretation.

To have a moral sense was to have a capacity for second-order attitudes—attitudes that have one’s other attitudes as their objects. This, they thought, was what makes man a moral agent in a sense in which other animals are not.

Can dogs have conscience?

A dog’s attitudes (they said) are all directed at objects external to the dog himself: he desires food, he desires what will make him warm, he desires to avoid the sources of pain. Perhaps, they might have said if they had known more about altruism among the animals, a dog might even desire that other dogs should not suffer.

But the dog cannot desire to have a certain attitude, and he cannot regret that he has certain attitudes.

A man, on the other hand, can want something (I want to hurt the person who hurt me) and at the same time can regret that he wants it (I disapprove of myself for wanting revenge, and wish that I had a more generous temperament).

It is this capacity for approving or disapproving of one’s own attitudes that constitute one’s conscience.

In Darwin’s notebooks for 1838-40 there are numerous references to these thinkers, and Darwin’s own treatment of conscience, elaborated years later in The Descent of Man, is similar to their treatment.

But Darwin thought that the very existence of conscience is puzzling: how can there be such a thing?

Conscience, as Darwin conceives it, is a phenomenon closely associated with conflict situations.

Facing a choice about what to so, a man may be pulled in different directions by conflicting “natural impulses”. For example, there may be a danger that he can avoid by running away and he may be afraid; or, there may be food that he can seize, and he may be hungry. At the same time, running away from the danger or seizing the food may be contrary to the interests of the community at large, and because he has “social instincts” he is disinclined to do those things. So whatever he does, he will be going against one or another of his natural impulses.

Suppose, then, his fear or his hunger wins out, and he acts contrary to the general welfare of the community. Later, when he reflects on what he has done, he feels bad about this, and regrets it. This is the deliverance of conscience; it is the wish that one, rather than another, of one’s attitudes prevailed.

Puzzle

Darwin found this puzzling because it seemed strange that one sort of “natural impulse”—the social instincts—should be thought better or more worthy of respect than any other. Why, in retrospect, are we uncomfortable with the fact that we acted on some instincts rather than on others, when they all equally “natural”?

As Darwin put it, “Why does man regret, even though he may endeavor to banish such regret, that he has followed the one natural impulse, rather than the other; and why does he further feel that he ought to regret his conduct? Man in this respect differs profoundly from the lower animals.”

Two solutions

The 18th century moralists had considered two general solutions to this problem:

First, we can distinguish between the strengths of the various impulses to action. Perhaps the social instincts are simply stronger than the others, so that when the man regrets giving in to fear or hunger the regret is produced by the superior strength of the social impulse.

This sort of explanation, however, does not seem to work. If the social impulse is stronger than fear or hunger, then why he did not act on it originally?

2nd solution

This sort of consideration led Butler to distinguish the strength of conscience from its authority. He held that the various springs of action form a natural hierarchy, with conscience at he top, so that conscience has a supremacy that does not depend on its strength.

Thus, even if an individual constantly acts contrary to conscience because his conscience is weak, while his other impulses are strong, his conscience still dictates what he ought to do because that is its natural function.

Darwin, however, regarded this as so much hocus-pocus, and sought a less exotic explanation.

“Butler and MacIntosh characterize moral sense by its ‘supremacy’—I make its supremacy solely due to greater duration of impression of social instincts, than other passions, or instincts.”

It was this notion of ‘greater duration’ that was to provide the key for Darwin’s explanation.

Darwin’s account

Suppose a man does something , out of fear or hunger, that harms the community. Then he reflects on what he has done. Now the social instincts are permanent, and persistent; but particular desires come and go. Therefore, when he reflects on his past conduct, his social instincts are still with him, but the particular desire that, at the time of action, overwhelmed the social instincts, is fading away. Thus he regrets what he did. This after-the-fact reflection is what we call ‘conscience’, and the fact that the social instincts are stronger at the time of reflection, even if they were not stronger at the time of the action, explains why such reflection results in their endorsement.

“Thus, as man cannot prevent old impressions continually passing through his mind, he will be compelled to compare the weaker impressions of, for instance, past hunger, or of vengeance satisfied or danger avoided at the cost of other men, with the instinct of sympathy and good-will to his fellows, which is still present and ever in some degree active in his mind. He will then feel in his imagination that a stronger instinct has yielded to one which now seems comparatively weak… At the moment of action, man will no doubt be apt to follow the stronger impulse; and though this may occasionally prompt him to the noblest deeds, it will far more commonly lead him to gratify his own desires at the expense of other men. But after their gratification, when past and weaker impressions are contrasted with the ever-enduring social instincts, retribution will surely come. Man will then feel dissatisfaction with himself, and will resolve with more or less force to act differently in the future. This is conscience; for conscience looks backwards and judges past actions, inducing that kind of dissatisfaction, which if weak we call regret, and if severe remorse.”

Admirable people

Completely admirable people: people’s social instincts are strong enough to overcome the particular inclinations—fear, hunger, etc.—which might otherwise lead them to act contrary to the general welfare.

Not completely admirable people:

(1) those who yield to temptation but later regret it

(2) those who have no regrets (‘essentially bad’ people: their social instincts are so weak, or even non-existent, that they do not even control later reflections. These are the people who have no conscience.)

Darwin: “If he has no such sympathy, and if his desires leading to bad actions are at the time strong, and when recalled are not overmastered by the persistent social instincts, then he is essentially a bad man; and the sole restraining motive left is the fear of punishment.”

How can there be such people? The natural explanation, from the standpoint of natural history, is that they are variations.

Moral progressDespite his acknowledgement of the existence of conscienceless men, Darwin was an optimist who believed, in good 19th century fashion, that the human race is advancing towards ever greater moral perfection.

His account of the nature of this progress, and of the conditions of human life that make it possible, followed naturally from his view about the role of reason in expanding the scope of the social instincts.

He envisioned an ever-widening circle of moral concern, that would spread beyond self and family to include neighbors and countrymen and eventually all mankind. And the human social instinct would go a step beyond even that, to include within its sphere of concern the other animals as well.

As man became more rational and as his social instincts were guided more and more by reason, “his sympathies became more tender and widely diffused, so as to extend to the men of all races, to the imbecile, the maimed, and other useless members of society, and finally to the lowered animals—so would the standard of his morality rise higher and higher.”

Discussion

Is the difference between humans and non-human animals in terms of social instinct a matter of degree?

Is the difference between humans and non-human animals in terms of rationality a matter of degree?

Is Darwin’s account of conscience (well-marked social instincts + advanced intellectual powers) plausible?

Does Darwin’s account succeed in naturalizing morality?

Is there anything distinctive about human morality?