Psychological egoism

From Wikipedia, the free encyclopedia

Psychological egoism is the view that humans are always motivated by self-interest, even in what seem to be acts of altruism. It claims that, when people choose to help others, they do so ultimately because of the personal benefits that they themselves expect to obtain, directly or indirectly, from doing so. This is a descriptive rather than normative view, since it only makes claims about how things are, not how they ought to be. It is, however, related to several other normative forms of egoism, such as ethical egoism and rational egoism.

A specific form of psychological egoism is psychological hedonism, the view that the ultimate motive for all voluntary human action is the desire to experience pleasure or to avoid pain. Many discussions of psychological egoism focus on this type, but the two are not the same: theorists have explained behavior motivated by self-interest without using pleasure and pain as the final causes of behavior. Psychological hedonism argues actions are caused by both a need for pleasure immediately and in the future. However, immediate gratification can be sacrificed for a chance of greater, future pleasure. Further, humans are not motivated to strictly avoid pain and only pursue pleasure, but, instead, humans will endure pain to achieve the greatest net pleasure. Accordingly, all actions are tools for increasing pleasure or decreasing pain, even those defined as altruistic and those that do not cause an immediate change in satisfaction levels.

Foundations

Beginning with ancient philosophy, Epicureanism claims humans live to maximize pleasure.  Epicurus argued the theory of human behavior being motivated by pleasure alone is evidenced from infancy to adulthood. Humanity performs altruistic, honorable, and virtuous acts not for the sake of another or because of a moral code but rather to increase the well being of the self.

In modern philosophy, Jeremy Bentham asserted, like Epicurus, that human behavior is governed by a need to increase pleasure and decrease pain. Bentham explicitly described what types and qualities of pain and pleasure exist, and how human motives are singularly explained using psychological hedonism. Bentham attempted to quantify psychological hedonism. Bentham endeavored to find the ideal human behavior based on hedonic calculus or the measurement of relative gains and losses in pain and pleasure to determine the most pleasurable action a human could choose in a situation.

From an evolutionary perspective, Herbert Spencer, a psychological egoist, argued that all animals primarily seek to survive and protect their lineage. Essentially, the need for the individual and for the individual's immediate family to live supersedes the others' need to live. All species attempt to maximize their own chances of survival and, therefore, well being. Spencer asserted the best adapted creatures will have their pleasure levels outweigh their pain levels in their environments. Thus, pleasure meant an animal was fulfilling its egoist goal of self survival, and pleasure would always be pursued because species constantly strive for survival.

Contributions to modern psychology

Psychoanalysis

Whether or not Sigmund Freud was a psychological egoist, his concept of the pleasure principle borrowed much from psychological egoism and psychological hedonism in particular. The pleasure principle rules the behavior of the Id which is an unconscious force driving humans to release tension from unfulfilled desires. When Freud introduced Thanatos and its opposing force, Eros, the pleasure principle emanating from psychological hedonism became aligned with the Eros, which drives a person to satiate sexual and reproductive desires. Alternatively, Thanatos seeks the cessation of pain through death and the end of the pursuit of pleasure: thus a hedonism rules Thanatos, but it centers on the complete avoidance of pain rather than psychological hedonist function which pursues pleasure and avoids pain. Therefore, Freud believed in qualitatively different hedonisms where the total avoidance of pain hedonism and the achievement of the greatest net pleasure hedonism are separate and associated with distinct functions and drives of the human psyche. Although Eros and Thanatos are ruled by qualitatively different types of hedonism, Eros remains under the rule of Jeremy Bentham's quantitative psychological hedonism because Eros seeks the greatest net pleasure.

Behaviorism

Traditional behaviorism dictates all human behavior is explained by classical conditioning and operant conditioning. Operant conditioning works through reinforcement and punishment which adds or removes pleasure and pain to manipulate behavior. Using pleasure and pain to control behavior means behaviorists assumed the principles of psychological hedonism could be applied to predicting human behavior. For example, Thorndike's law of effect states that behaviors associated with pleasantness will be learned and those associated with pain will be extinguished. Often, behaviorist experiments using humans and animals are built around the assumption that subjects will pursue pleasure and avoid pain. Although psychological hedonism is incorporated into the fundamental principles and experimental designs of behaviorism, behaviorism itself explains and interprets only observable behavior and therefore does not theorize about the ultimate cause of human behavior. Thus, behaviorism uses but does not strictly support psychological hedonism over other understandings of the ultimate drive of human behavior.

The debate

Psychological egoism is controversial. Proponents cite evidence from introspection: reflection on one's own actions may reveal their motives and intended results to be based on self-interest. Psychological egoists and hedonists have found through numerous observations of natural human behavior that behavior can be manipulated through reward and punishment both of which have direct effects of pain and pleasure. Also, the work of some social scientists has empirically supported this theory. Further, they claim psychological egoism posits a theory that is a more parsimonious explanation than competing theories.

Opponents have argued that psychological egoism is not more parsimonious than other theories. For example, a theory that claims altruism occurs for the sake of altruism explains altruism with less complexity than the egoistic approach. The psychological egoist asserts humans act altruistically for selfish reasons even when cost of the altruistic action is far outweighed by the reward of acting selfishly because altruism is performed to fulfill the desire of a person to act altruistically. Other critics argue that it is false either because it is an over-simplified interpretation of behavior or that there exists empirical evidence of altruistic behaviour. Recently, some have argued that evolutionary theory provides evidence against it.

Critics have stated that proponents of psychological egoism often confuse the satisfaction of their own desires with the satisfaction of their own self-regarding desires. Even though it is true that every human being seeks his own satisfaction, this sometimes may only be achieved via the well-being of his neighbor. An example of this situation could be phoning for an ambulance when a car accident has happened. In this case, the caller desires the well-being of the victim, even though the desire itself is the caller's own.

To counter this critique, psychological egoism asserts that all such desires for the well being of others are ultimately derived from self-interest. For example, German philosopher Friedrich Nietzsche was a psychological egoist for some of his career, though he is said to have repudiated that later in his campaign against morality. He argues in §133 of The Dawn, that in such cases compassionate impulses arise out of the projection of our identity unto the object of our feeling. He gives some hypothetical examples as illustrations to his thesis: that of a person, feeling horrified after witnessing a personal feud, coughing blood, or that of the impulse felt to save a person who is drowning in the water. In such cases, according to Nietzsche, there comes into play unconscious fears regarding our own safety. The suffering of another person is felt as a threat to our own happiness and sense of safety, because it reveals our own vulnerability to misfortunes, and thus, by relieving it, one could also ameliorate those personal sentiments. Essentially, proponents argue that altruism is rooted in self-interest whereas opponents claim altruism occurs for altruism's sake or is caused by a non-selfish reason.

The problem of apparent altruism

David Hume once wrote, "What interest can a fond mother have in view, who loses her health by assiduous attendance on her sick child, and afterwards languishes and dies of grief, when freed, by its death [the child's], from the slavery of that attendance?". It seems incorrect to describe such a mother's goal as self-interested.

Psychological egoists, however, respond that helping others in such ways is ultimately motivated by some form of self-interest, such as non-sensory satisfaction, the expectation of reciprocation, the desire to gain respect or reputation, or by the expectation of a reward in a putative afterlife. The helpful action is merely instrumental to these ultimately selfish goals.

In the ninth century, Mohammed Ibn Al-Jahm Al-Barmaki (محمد بن الجـَهْم البَرمَكي) has been quoted saying:

"No one deserves thanks from another about something he has done for him or goodness he has done, he is either willing to get a reward from God, therefore he wanted to serve himself, or he wanted to get a reward from people, therefore, he has done that to get profit for himself, or to be mentioned and praised by people, therefore, to it is also for himself, or due to his mercy and tenderheartedness, so he has simply done that goodness to pacify these feelings and treat himself."

This sort of explanation appears to be close to the view of La Rochefoucauld (and perhaps Hobbes).

According to psychological hedonism, the ultimate egoistic motive is to gain good feelings of pleasure and avoid bad feelings of pain. Other, less restricted forms of psychological egoism may allow the ultimate goal of a person to include such things as avoiding punishments from oneself or others (such as guilt or shame) and attaining rewards (such as pride, self-worth, power or reciprocal beneficial action).

Some psychologists explain empathy in terms of psychological hedonism. According to the "merge with others hypothesis", empathy increases the more an individual feels like they are one with another person, and decreases as the oneness decreases. Therefore, altruistic actions emanating from empathy and empathy itself are caused by making others' interests our own, and the satisfaction of their desires becomes our own, not just theirs. Both cognitive studies and neuropsychological experiments have provided evidence for this theory: as humans increase our oneness with others our empathy increases, and as empathy increases our inclination to act altruistically increases. Neuropsychological studies have linked mirror neurons to humans experiencing empathy. Mirror neurons are activated both when a human (or animal) performs an action and when they observe another human (or animal) performs the same action. Researchers have found that the more these mirror neurons fire the more human subjects report empathy. From a neurological perspective, scientists argue that when a human empathizes with another, the brain operates as if the human is actually participating in the actions of the other person. Thus, when performing altruistic actions motivated by empathy, humans experience someone else's pleasure of being helped. Therefore, in performing acts of altruism, people act in their own self interests even at a neurological level.

Criticisms

Explanatory power

Even accepting the theory of universal positivity, it is difficult to explain, for example, the actions of a soldier who sacrifices his life by jumping on a grenade in order to save his comrades. In this case, there is simply no time to experience positivity toward one's actions, although a psychological egoist may argue that the soldier experiences moral positivity in knowing that he is sacrificing his life to ensure the survival of his comrades, or that he is avoiding negativity associated with the thought of all his comrades dying. Psychological egoists argue that although some actions may not clearly cause physical nor social positivity, nor avoid negativity, one's current contemplation or reactionary mental expectation of these is the main factor of the decision. When a dog is first taught to sit, it is given a biscuit. This is repeated until, finally, the dog sits without requiring a biscuit. Psychological egoists could claim that such actions which do not 'directly' result in positivity, or reward, are not dissimilar from the actions of the dog. In this case, the action (sitting on command) will have become a force of habit, and breaking such a habit would result in mental discomfort. This basic theory of conditioning behavior, applied to other seemingly ineffective positive actions, can be used to explain moral responses that are instantaneous and instinctive such as the soldier jumping on the grenade.

Circularity

Psychological egoism has been accused of being circular: "If a person willingly performs an act, that means he derives personal enjoyment from it; therefore, people only perform acts that give them personal enjoyment." In particular, seemingly altruistic acts must be performed because people derive enjoyment from them and are therefore, in reality, egoistic. This statement is circular because its conclusion is identical to its hypothesis: it assumes that people only perform acts that give them personal enjoyment, and concludes that people only perform acts that give them personal enjoyment. This objection was tendered by William Hazlitt and Thomas Macaulay in the 19th century, and has been restated many times since. An earlier version of the same objection was made by Joseph Butler in 1726.

Joel Feinberg, in his 1958 paper "Psychological Egoism", embraces a similar critique by drawing attention to the infinite regress of psychological egoism. He expounds it in the following cross-examination:

"All men desire only satisfaction."

"Satisfaction of what?"

"Satisfaction of their desires."

"Their desires for what?"

"Their desires for satisfaction."

"Satisfaction of what?"

"Their desires."

"For what?"

"For satisfaction"—etc., ad infinitum.

Evolutionary argument

In their 1998 book, Unto Others, Sober and Wilson detailed an evolutionary argument based on the likelihood for egoism to evolve under the pressures of natural selection. Specifically, they focus on the human behavior of parental care. To set up their argument, they propose two potential psychological mechanisms for this. The hedonistic mechanism is based on a parent's ultimate desire for pleasure or the avoidance of pain and a belief that caring for its offspring will be instrumental to that. The altruistic mechanism is based on an altruistic ultimate desire to care for its offspring.

Sober and Wilson argue that when evaluating the likelihood of a given trait to evolve, three factors must be considered: availability, reliability and energetic efficiency. The genes for a given trait must first be available in the gene pool for selection. The trait must then reliably produce an increase in fitness for the organism. The trait must also operate with energetic efficiency to not limit the fitness of the organism. Sober and Wilson argue that there is neither reason to suppose that an altruistic mechanism should be any less available than a hedonistic one nor reason to suppose that the content of thoughts and desires (hedonistic vs. altruistic) should impact energetic efficiency. As availability and energetic efficiency are taken to be equivalent for both mechanisms it follows that the more reliable mechanism will then be the more likely mechanism.

For the hedonistic mechanism to produce the behavior of caring for offspring, the parent must believe that the caring behavior will produce pleasure or avoidance of pain for the parent. Sober and Wilson argue that the belief also must be true and constantly reinforced, or it would not be likely enough to persist. If the belief fails then the behavior is not produced. The altruistic mechanism does not rely on belief; therefore, they argue that it would be less likely to fail than the alternative, i.e. more reliable.

Reciprocal altruism

From Wikipedia, the free encyclopedia

 

Diagram showing reciprocal altruism

In evolutionary biology, reciprocal altruism is a behaviour whereby an organism acts in a manner that temporarily reduces its fitness while increasing another organism's fitness, with the expectation that the other organism will act in a similar manner at a later time. The concept was initially developed by Robert Trivers to explain the evolution of cooperation as instances of mutually altruistic acts. The concept is close to the strategy of "tit for tat" used in game theory.

Theory

The concept of "reciprocal altruism", as introduced by Trivers, suggests that altruism, defined as an act of helping another individual while incurring some cost for this act, could have evolved since it might be beneficial to incur this cost if there is a chance of being in a reverse situation where the individual who was helped before may perform an altruistic act towards the individual who helped them initially. This concept finds its roots in the work of W.D. Hamilton, who developed mathematical models for predicting the likelihood of an altruistic act to be performed on behalf of one's kin.

Putting this into the form of a strategy in a repeated prisoner’s dilemma would mean to cooperate unconditionally in the first period and behave cooperatively (altruistically) as long as the other agent does as well. If chances of meeting another reciprocal altruist are high enough, or if the game is repeated for a long enough amount of time, this form of altruism can evolve within a population.

This is close to the notion of "tit for tat" introduced by Anatol Rapoport, although there still seems a slight distinction in that "tit for tat" cooperates in the first period and from thereon always replicates an opponent’s previous action, whereas “reciprocal altruists” stop cooperation in the first instance of non-cooperation by an opponent and stay non-cooperative from thereon. This distinction leads to the fact that in contrast to reciprocal altruism, tit for tat may be able to restore cooperation under certain conditions despite cooperation having broken down.

Christopher Stephens shows a set of necessary and jointly sufficient conditions “… for an instance of reciprocal altruism:

1. the behaviour must reduce a donor's fitness relative to a selfish alternative;
2. the fitness of the recipient must be elevated relative to non-recipients;
3. the performance of the behaviour must not depend on the receipt of an immediate benefit;
4. conditions 1, 2, and 3 must apply to both individuals engaging in reciprocal helping.

There are two additional conditions necessary "…for reciprocal altruism to evolve:"

• A mechanism for detecting 'cheaters' must exist.
• A large (indefinite) number of opportunities to exchange aid must exist.

The first two conditions are necessary for altruism as such, while the third is distinguishing reciprocal altruism from simple mutualism and the fourth makes the interaction reciprocal. Condition number five is required as otherwise non-altruists may always exploit altruistic behaviour without any consequences and therefore evolution of reciprocal altruism would not be possible. However, it is pointed out that this “conditioning device” does not need to be conscious. Condition number six is required to avoid cooperation breakdown through backwards induction—a possibility suggested by game theoretical models.

Examples

The following examples could be understood as altruism. However, showing reciprocal altruism in an unambiguous way requires more evidence as will be shown later.

Cleaner fish

Cleaning symbiosis: a small cleaner wrasse (Labroides dimidiatus) with advertising coloration services a big eye squirrelfish (Priacanthus hamrur) in an apparent example of reciprocal altruism.

An example of reciprocal altruism is cleaning symbiosis, such as between cleaner fish and their hosts, though cleaners include shrimps and birds, and clients include fish, turtles, octopuses and mammals. Aside from the apparent symbiosis of the cleaner and the host during actual cleaning, which cannot be interpreted as altruism, the host displays additional behaviour that meets the criteria for altruism:

The host fish allows the cleaner fish free entrance and exit and does not eat the cleaner, even after the cleaning is done. The host signals the cleaner it is about to depart the cleaner's locality, even when the cleaner is not in its body. The host sometimes chases off possible dangers to the cleaner.

The following evidence supports the hypothesis:

The cleaning by cleaners is essential for the host. In the absence of cleaners the hosts leave the locality or suffer from injuries inflicted by ecto-parasites. There is difficulty and danger in finding a cleaner. Hosts leave their element to get cleaned. Others wait no longer than 30 seconds before searching for cleaners elsewhere.

A key requirement for the establishment of reciprocal altruism is that the same two individuals must interact repeatedly, as otherwise the best strategy for the host would be to eat the cleaner as soon as cleaning was complete. This constraint imposes both a spatial and a temporal condition on the cleaner and on its host. Both individuals must remain in the same physical location, and both must have a long enough lifespan, to enable multiple interactions. There is reliable evidence that individual cleaners and hosts do indeed interact repeatedly.

This example meets some, but not all, of the criteria described in Trivers’s model. In the cleaner-host system the benefit to the cleaner is always immediate. However, the evolution of reciprocal altruism is contingent on opportunities for future rewards through repeated interactions. In one study, nearby host fish observed "cheater" cleaners and subsequently avoided them. In these examples, true reciprocity is difficult to demonstrate since failure means the death of the cleaner. However, if Randall’s claim that hosts sometimes chase off possible dangers to the cleaner is correct, an experiment might be constructed in which reciprocity could be demonstrated.

Warning calls in birds

Eurasian jay, Garrulus glandarius, gives loud alarm calls from its tree perch when it sees a predator.

Warning calls, although exposing a bird and putting it in danger, are frequently given by birds. An explanation in terms of altruistic behaviors given by Trivers:

It has been shown that predators learn specific localities and specialize individually on prey types and hunting techniques. It is therefore disadvantageous for a bird to have a predator eat a conspecific, because the experienced predator may then be more likely to eat him. Alarming another bird by giving a warning call tends to prevent predators from specializing on the caller’s species and locality. In this way, birds in areas in which warning calls are given will be at a selective advantage relative to birds in areas free from warning calls.

Nevertheless, this presentation lacks important elements of reciprocity. It is very hard to detect and ostracize cheaters. There is no evidence that a bird refrains from giving calls when another bird is not reciprocating, nor evidence that individuals interact repeatedly. Given the aforementioned characteristics of bird calling, a continuous bird emigration and immigration environment (true of many avian species) is most likely to be partial to cheaters, since selection against the selfish gene is unlikely.

Another explanation for warning calls is that these are not warning calls at all: A bird, once it has detected a bird of prey, calls to signal to the bird of prey that it was detected, and that there is no use trying to attack the calling bird. Two facts support this hypothesis:

• The call frequencies match the hearing range of the predator bird.
• Calling birds are less attacked—predator birds attack calling birds less frequently than other birds.

Nest protecting

Arctic terns protect their offspring extremely aggressively by very quick drop-downs from a stationary flight over their enemies. Other birds often benefit from this behavior by breeding very close to the Arctic terns.

Red-winged blackbird males help defend neighbor's nests. There are many theories as to why males behave this way. One is that males only defend other nests which contain their extra-pair offspring. Extra-pair offspring is juveniles which may contain some of the male bird's DNA. Another is the tit-for-tat strategy of reciprocal altruism. A third theory is, males help only other closely related males. A study done by The Department of Fisheries and Wildlife provided evidence that males used a tit-for-tat strategy. The Department of Fisheries and Wildlife tested many different nests by placing stuffed crows by nests, and then observing behavior of neighboring males. The behaviors they looked for included the number of calls, dives, and strikes. After analyzing the results, there was not significance evidence for kin selection; the presence of extra-pair offspring did not affect the probability of help in nest defense. However, males reduced the amount of defense given to neighbors when neighbor males reduced defense for their nests. This demonstrates a tit-for-tat strategy, where animals help those who previously helped them. This strategy is one type of reciprocal altruism.

Vampire bats

Vampire bats also display reciprocal altruism, as described by Wilkinson. The bats feed each other by regurgitating blood. Since bats only feed on blood and will die after just 70 hours of not eating, this food sharing is a great benefit to the receiver and a great cost to the giver. To qualify for reciprocal altruism, the benefit to the receiver would have to be larger than the cost to the donor. This seems to hold as these bats usually die if they do not find a blood meal two nights in a row. Also, the requirement that individuals who have behaved altruistically in the past are helped by others in the future is confirmed by the data. However, the consistency of the reciprocal behaviour, namely that a previously non-altruistic bat is refused help when it requires it, has not been demonstrated. Therefore, the bats do not seem to qualify yet as an unequivocal example of reciprocal altruism.

Primates

Grooming in primates meets the conditions for reciprocal altruism according to some studies. One of the studies in vervet monkeys shows that among unrelated individuals, grooming induce higher chance of attending to each other's calls for aid. However, vervet monkeys also display grooming behaviors within group members, displaying alliances. This would demonstrate vervet monkey's grooming behavior as a part of kin selection since the activity is done between siblings in this study. Moreover, following the criteria by Stephen, if the study is to be an example of reciprocal altruism, it must prove the mechanism for detecting cheaters.

Regulation by emotional disposition

In comparison to that of other animals, the human altruistic system is a sensitive and unstable one. Therefore, the tendency to give, to cheat, and the response to other’s acts of giving and cheating must be regulated by a complex psychology in each individual, social structures, and cultural traditions. Individuals differ in the degree of these tendencies and responses. According to Trivers, the following emotional dispositions and their evolution can be understood in terms of regulation of altruism.

• Friendship and emotions of liking and disliking.
• Moralistic aggression. A protection mechanism from cheaters acts to regulate the advantage of cheaters in selection against altruists. The moralistic altruist may want to educate or even punish a cheater.
• Gratitude and sympathy. A fine regulation of altruism can be associated with gratitude and sympathy in terms of cost/benefit and the level in which the beneficiary will reciprocate.
• Guilt and reparative altruism. Prevents the cheater from cheating again. The cheater shows regret to avoid paying too dearly for past acts.
• Subtle cheating. A stable evolutionary equilibrium could include a low percentage of mimics in controversial support of adaptive sociopathy.
• Trust and suspicion. These are regulators for cheating and subtle cheating.
• Partnerships. Altruism to create friendships.

It is not known how individuals pick partners as there has been little research on choice. Modeling indicates that altruism about partner choices is unlikely to evolve, as costs and benefits between multiple individuals are variable. Therefore, the time or frequency of reciprocal actions contributes more to an individual's choice of partner than the reciprocal act itself.

Golden Rule

From Wikipedia, the free encyclopedia

The Golden Rule is the principle of treating others as one would wish to be treated. It is a maxim that is found in many religions and cultures. The Golden Rule can be considered a law of reciprocity in some religions, although other religions treat it differently. The maxim may appear as either a positive or negative injunction governing conduct.

• One should treat others as one would like others to treat oneself (positive or directive form).
• One should not treat others in ways that one would not like to be treated (negative or prohibitive form).
• What you wish upon others, you wish upon yourself (empathic or responsive form).

The idea dates at least to the early Confucian times (551–479 BCE) according to Rushworth Kidder, who identifies that this concept appears prominently in Buddhism, Christianity, Hinduism, Judaism, Taoism, Zoroastrianism, and "the rest of the world's major religions". 143 leaders encompassing the world's major faiths endorsed the Golden Rule as part of the 1993 "Declaration Toward a Global Ethic", including the Baha'i Faith, Brahmanism, Brahma Kumaris, Buddhism, Christianity, Hinduism, Indigenous, Interfaith, Islam, Jainism, Judaism, Native American, Neo-Pagan, Sikhism, Taoism, Theosophist, Unitarian Universalist and Zoroastrian. According to Greg M. Epstein, " 'do unto others' ... is a concept that essentially no religion misses entirely," but belief in God is not necessary to endorse it. Simon Blackburn also states that the Golden Rule can be "found in some form in almost every ethical tradition".

The Golden Rule has been criticised for a number of reasons, to include the possibility of differing preferences, situations where there is a significant power disparity between actors (e.g., a judge and a prisoner being judged), and the need to apply the Golden Rule along with other ethical action guides.

Etymology

The term "Golden Rule", or "Golden law", began to be used widely in the early 17th century in Britain by Anglican theologians and preachers; the earliest known usage is that of Anglicans Charles Gibbon and Thomas Jackson in 1604.

Ancient history

Ancient Egypt

Possibly the earliest affirmation of the maxim of reciprocity, reflecting the ancient Egyptian goddess Ma'at, appears in the story of The Eloquent Peasant, which dates to the Middle Kingdom (c. 2040–1650 BC): "Now this is the command: Do to the doer to make him do."^[10][11] This proverb embodies the do ut des principle.^[12] A Late Period (c. 664–323 BC) papyrus contains an early negative affirmation of the Golden Rule: "That which you hate to be done to you, do not do to another."^[13]

Ancient India

Sanskrit tradition

In Mahābhārata, the ancient epic of India, there is a discourse in which the wise minister Vidura advises the King Yuddhiśhṭhira

Listening to wise scriptures, austerity, sacrifice, respectful faith, social welfare, forgiveness, purity of intent, compassion, truth and self-control—are the ten wealth of character (self). O king aim for these, may you be steadfast in these qualities. These are the basis of prosperity and rightful living. These are highest attainable things. All worlds are balanced on dharma, dharma encompasses ways to prosperity as well. O King, dharma is the best quality to have, wealth the medium and desire (kāma) the lowest. Hence, (keeping these in mind), by self-control and by making dharma (right conduct) your main focus, treat others as you treat yourself.

— Mahābhārata Shānti-Parva 167:9

Tamil tradition

In Chapter 32 in the Part on Virtue of the Tirukkuṛaḷ (c. 200 BC – c. 500 AD), Tiruvalluvar says: "Do not do to others what you know has hurt yourself" (K. 316.); "Why does one hurt others knowing what it is to be hurt?" (K. 318). He furthermore opined that it is the determination of the spotless (virtuous) not to do evil, even in return, to those who have cherished enmity and done them evil. (K. 312) The (proper) punishment to those who have done evil (to you), is to put them to shame by showing them kindness, in return and to forget both the evil and the good done on both sides (K. 314)

Ancient Greece

The Golden Rule in its prohibitive (negative) form was a common principle in ancient Greek philosophy. Examples of the general concept include:

• "Avoid doing what you would blame others for doing." – Thales (c. 624–546 BC)
• "What you do not want to happen to you, do not do it yourself either. " – Sextus the Pythagorean. The oldest extant reference to Sextus is by Origen in the third century of the common era.
• "Do not do to others that which angers you when they do it to you." – Isocrates (436–338 BC)

Ancient Persia

The Pahlavi Texts of Zoroastrianism (c. 300 BC–1000 AD) were an early source for the Golden Rule: "That nature alone is good which refrains from doing to another whatsoever is not good for itself." Dadisten-I-dinik, 94,5, and "Whatever is disagreeable to yourself do not do unto others." Shayast-na-Shayast 13:29

Ancient Rome

Seneca the Younger (c. 4 BC–65 AD), a practitioner of Stoicism (c. 300 BC–200 AD) expressed the Golden Rule in his essay regarding the treatment of slaves: "Treat your inferior as you would wish your superior to treat you."

Religious context

According to Simon Blackburn, the Golden Rule "can be found in some form in almost every ethical tradition".

Abrahamic religions

Judaism

A rule of altruistic reciprocity was first stated positively in a well-known Torah verse (Hebrew: ואהבת לרעך כמוך‬):

You shall not take vengeance or bear a grudge against your kinsfolk. Love your neighbor as yourself: I am the LORD.

— Leviticus 19:18

Hillel the Elder (c. 110 BC – 10 AD), used this verse as a most important message of the Torah for his teachings. Once, he was challenged by a gentile who asked to be converted under the condition that the Torah be explained to him while he stood on one foot. Hillel accepted him as a candidate for conversion to Judaism but, drawing on Leviticus 19:18, briefed the man:

What is hateful to you, do not do to your fellow: this is the whole Torah; the rest is the explanation; go and learn.

— Shabbath folio:31a, Babylonian Talmud

Hillel recognized brotherly love as the fundamental principle of Jewish ethics. Rabbi Akiva agreed and suggested that the principle of love must have its foundation in Genesis chapter 1, which teaches that all men are the offspring of Adam, who was made in the image of God (Sifra, Ḳedoshim, iv.; Yer. Ned. ix. 41c; Genesis Rabba 24). According to Jewish rabbinic literature, the first man Adam represents the unity of mankind. This is echoed in the modern preamble of the Universal Declaration of Human Rights. And it is also taught, that Adam is last in order according to the evolutionary character of God's creation:

Why was only a single specimen of man created first? To teach us that he who destroys a single soul destroys a whole world and that he who saves a single soul saves a whole world; furthermore, so no race or class may claim a nobler ancestry, saying, 'Our father was born first'; and, finally, to give testimony to the greatness of the Lord, who caused the wonderful diversity of mankind to emanate from one type. And why was Adam created last of all beings? To teach him humility; for if he be overbearing, let him remember that the little fly preceded him in the order of creation.

The Jewish Publication Society's edition of Leviticus states:

Thou shalt not hate thy brother. in thy heart; thou shalt surely rebuke thy neighbour, and not bear sin because of him. 18 Thou shalt not take vengeance, nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I am the LORD.

This Torah verse represents one of several versions of the Golden Rule, which itself appears in various forms, positive and negative. It is the earliest written version of that concept in a positive form.

At the turn of the eras, the Jewish rabbis were discussing the scope of the meaning of Leviticus 19:18 and 19:34 extensively:

The stranger who resides with you shall be to you as one of your citizens; you shall love him as yourself, for you were strangers in the land of Egypt: I the LORD am your God.

— Leviticus 19:34

Commentators summed up foreigners (= Samaritans), proselytes (= 'strangers who resides with you') (Rabbi Akiva, bQuid 75b) or Jews (Rabbi Gamaliel, yKet 3, 1; 27a) to the scope of the meaning.
On the verse, "Love your fellow as yourself," the classic commentator Rashi quotes from Torat Kohanim, an early Midrashic text regarding the famous dictum of Rabbi Akiva: "Love your fellow as yourself – Rabbi Akiva says this is a great principle of the Torah."

Israel's postal service quoted from the previous Leviticus verse when it commemorated the Universal Declaration of Human Rights on a 1958 postage stamp.

Christianity

Jesus taught the Golden Rule during the Sermon on the Mount.

The "Golden Rule" was given by Jesus of Nazareth (Matthew 7:12 NCV, see also Luke 6:31). The common English phrasing is "Do unto others as you would have them do unto you". A similar form of the phrase appeared in a Catholic catechism around 1567 (certainly in the reprint of 1583). The Golden Rule is stated positively numerous times in the Hebrew Pentateuch as well as the Prophets and Writings. Leviticus 19:18 ("Forget about the wrong things people do to you, and do not try to get even. Love your neighbor as you love yourself."; see also Great Commandment) and Leviticus 19:34 ("But treat them just as you treat your own citizens. Love foreigners as you love yourselves, because you were foreigners one time in Egypt. I am the Lord your God.").

The Old Testament Deuterocanonical books of Tobit and Sirach, accepted as part of the Scriptural canon by Catholic Church, Eastern Orthodoxy, and the Non-Chalcedonian Churches, express a negative form of the golden rule:

"Do to no one what you yourself dislike."

— Tobit 4:15

"Recognize that your neighbor feels as you do, and keep in mind your own dislikes."

— Sirach 31:15

Two passages in the New Testament quote Jesus of Nazareth espousing the positive form of the Golden rule:

Matthew 7:12

Do to others what you want them to do to you. This is the meaning of the law of Moses and the teaching of the prophets.

Luke 6:31

Do to others what you would want them to do to you.

A similar passage, a parallel to the Great Commandment, is Luke 10:25-28

²⁵And one day an authority on the law stood up to put Jesus to the test. "Teacher," he asked, "what must I do to receive eternal life?"


²⁶What is written in the Law?" Jesus replied. "How do you understand it?" ²⁷He answered, " ‘Love the Lord your God with all your heart and with all your soul. Love him with all your strength and with all your mind.’(Deuteronomy 6:5) And, ‘Love your neighbor as you love yourself.’ " ²⁸"You have answered correctly," Jesus replied. "Do that, and you will live.".

The passage in the book of Luke then continues with Jesus answering the question, "Who is my neighbor?", by telling the parable of the Good Samaritan, indicating that "your neighbor" is anyone in need. This extends to all, including those who are generally considered hostile.

Jesus' teaching goes beyond the negative formulation of not doing what one would not like done to themselves, to the positive formulation of actively doing good to another that, if the situations were reversed, one would desire that the other would do for them. This formulation, as indicated in the parable of the Good Samaritan, emphasizes the needs for positive action that brings benefit to another, not simply restraining oneself from negative activities that hurt another. Taken as a rule of judgment, both formulations of the golden rule, the negative and positive, are equally applicable.

In one passage of the New Testament, Paul the Apostle refers to the golden rule:
Galatians 5:14

¹⁴For all the law is fulfilled in one word, even in this; Thou shalt love thy neighbour as thyself.

Islam

The Arabian peninsula was known to not practice the golden rule prior to the advent of Islam. "Pre-Islamic Arabs regarded the survival of the tribe, as most essential and to be ensured by the ancient rite of blood vengeance"
However, this all changed when Muhammad came on the scene:

Fakir al-Din al-Razi and several other Qur'anic commentators have pointed out that Qur'an 83:1-6 is an implicit statement of the Golden Rule, which is explicitly stated in the tradition, "Pay, Oh Children of Adam, as you would love to be paid, and be just as you would love to have justice!" 

Similar examples of the golden rule are found in the hadith of the prophet Muhammad. The hadith recount what the prophet is believed to have said and done, and traditionally Muslims regard the hadith as second to only the Qur'an as a guide to correct belief and action."

From the hadith, the collected oral and written accounts of Muhammad and his teachings during his lifetime:

A Bedouin came to the prophet, grabbed the stirrup of his camel and said: O the messenger of God! Teach me something to go to heaven with it. Prophet said: "As you would have people do to you, do to them; and what you dislike to be done to you, don't do to them. Now let the stirrup go!" [This maxim is enough for you; go and act in accordance with it!]"

— Kitab al-Kafi, vol. 2, p. 146

None of you [truly] believes until he wishes for his brother what he wishes for himself.

— An-Nawawi's Forty Hadith 13 (p. 56)

Seek for mankind that of which you are desirous for yourself, that you may be a believer.

— Sukhanan-i-Muhammad (Teheran, 1938)

That which you want for yourself, seek for mankind.

The most righteous person is the one who consents for other people what he consents for himself, and who dislikes for them what he dislikes for himself.

Ali ibn Abi Talib (4th Caliph in Sunni Islam, and first Imam in Shia Islam) says:

O' my child, make yourself the measure (for dealings) between you and others. Thus, you should desire for others what you desire for yourself and hate for others what you hate for yourself. Do not oppress as you do not like to be oppressed. Do good to others as you would like good to be done to you. Regard bad for yourself whatever you regard bad for others. Accept that (treatment) from others which you would like others to accept from you... Do not say to others what you do not like to be said to you.

— Nahjul Balaghah, Letter 31

Indian religions

Hinduism

One should never do that to another which one regards as injurious to one’s own self. This, in brief, is the rule of dharma. Other behavior is due to selfish desires.

— Brihaspati, Mahabharata (Anusasana Parva, Section CXIII, Verse 8)

By making dharma your main focus, treat others as you treat yourself

Also,

श्रूयतां धर्मसर्वस्वं श्रुत्वा चाप्यवधार्यताम्।
आत्मनः प्रतिकूलानि परेषां न समाचरेत्।।

If the entire Dharma can be said in a few words, then it is—that which is unfavorable to us, do not do that to others.

— Padmapuraana, shrushti 19/357–358

Buddhism

Buddha (Siddhartha Gautama, c. 623–543 BC) made this principle one of the cornerstones of his ethics in the 6th century BC. It occurs in many places and in many forms throughout the Tripitaka.

Comparing oneself to others in such terms as "Just as I am so are they, just as they are so am I," he should neither kill nor cause others to kill.

— Sutta Nipata 705

One who, while himself seeking happiness, oppresses with violence other beings who also desire happiness, will not attain happiness hereafter.

— Dhammapada 10. Violence

Hurt not others in ways that you yourself would find hurtful.

— Udanavarga 5:18

Putting oneself in the place of another, one should not kill nor cause another to kill.

Jainism

The Golden Rule is paramount in the Jainist philosophy and can be seen in the doctrines of Ahimsa and Karma. As part of the prohibition of causing any living beings to suffer, Jainism forbids inflicting upon others what is harmful to oneself.
The following quotation from the Acaranga Sutra sums up the philosophy of Jainism:

Nothing which breathes, which exists, which lives, or which has essence or potential of life, should be destroyed or ruled over, or subjugated, or harmed, or denied of its essence or potential.

In support of this Truth, I ask you a question – "Is sorrow or pain desirable to you ?" If you say "yes it is", it would be a lie. If you say, "No, It is not" you will be expressing the truth. Just as sorrow or pain is not desirable to you, so it is to all which breathe, exist, live or have any essence of life. To you and all, it is undesirable, and painful, and repugnant.

A man should wander about treating all creatures as he himself would be treated.

— Sutrakritanga, 1.11.33

In happiness and suffering, in joy and grief, we should regard all creatures as we regard our own self.

— Lord Mahavira, 24th Tirthankara

Saman Suttam of Jinendra Varni gives further insight into this precept:-

Just as pain is not agreeable to you, it is so with others. Knowing this principle of equality treat other with respect and compassion.

— Suman Suttam, verse 150

Killing a living being is killing one's own self; showing compassion to a living being is showing compassion to oneself. He who desires his own good, should avoid causing any harm to a living being.

— Suman Suttam, verse 151

Sikhism

Precious like jewels are the minds of all. To hurt them is not at all good. If thou desirest thy Beloved, then hurt thou not anyone's heart.

— Guru Arjan Dev Ji 259, Guru Granth Sahib

East Asian religions

Confucianism

己所不欲，勿施於人。

"What you do not wish for yourself, do not do to others."

子貢問曰："有一言而可以終身行之者乎"？子曰："其恕乎！己所不欲、勿施於人。"

Zi gong (a disciple of Confucius) asked: "Is there any one word that could guide a person throughout life?"

The Master replied: "How about 'shu' [reciprocity]: never impose on others what you would not choose for yourself?"

--Confucius, Analects XV.24, tr. David Hinton (another translation is in the online Chinese Text Project)

The same idea is also presented in V.12 and VI.30 of the Analects (c. 500 BC), which can be found in the online Chinese Text Project. The phraseology differs from the Christian version of the Golden Rule. It does not presume to do anything unto others, but merely to avoid doing what would be harmful. It does not preclude doing good deeds and taking moral positions, but there is slim possibility for a Confucian missionary outlook, such as one can justify with the Christian Golden Rule.

Taoism

The sage has no interest of his own, but takes the interests of the people as his own. He is kind to the kind; he is also kind to the unkind: for Virtue is kind. He is faithful to the faithful; he is also faithful to the unfaithful: for Virtue is faithful.

— Tao Te Ching, Chapter 49

Regard your neighbor's gain as your own gain, and your neighbor's loss as your own loss.

— T'ai Shang Kan Ying P'ien

Mohism

If people regarded other people’s states in the same way that they regard their own, who then would incite their own state to attack that of another? For one would do for others as one would do for oneself. If people regarded other people’s cities in the same way that they regard their own, who then would incite their own city to attack that of another? For one would do for others as one would do for oneself. If people regarded other people’s families in the same way that they regard their own, who then would incite their own family to attack that of another? For one would do for others as one would do for oneself. And so if states and cities do not attack one another and families do not wreak havoc upon and steal from one another, would this be a harm to the world or a benefit? Of course one must say it is a benefit to the world.

— Mozi, c. 400 BC

Mozi regarded the golden rule as a corollary to the cardinal virtue of impartiality, and encouraged egalitarianism and selflessness in relationships.

Iranian religions

Zoroastrianism

Do not do unto others whatever is injurious to yourself. -- Shayast-na-Shayast 13.29

New religious movements

Bahá'í Faith

The writings of the Bahá'í Faith encourages everyone to treat others as they would treat themselves and even prefer others over oneself:

O SON OF MAN! Deny not My servant should he ask anything from thee, for his face is My face; be then abashed before Me.

— Bahá'u'lláh

Blessed is he who preferreth his brother before himself.

— Bahá'u'lláh

And if thine eyes be turned towards justice, choose thou for thy neighbour that which thou choosest for thyself.

— Bahá'u'lláh

Ascribe not to any soul that which thou wouldst not have ascribed to thee, and say not that which thou doest not.

— Bahá'u'lláh

Wicca

Here ye these words and heed them well, the words of Dea, thy Mother Goddess, "I command thee thus, O children of the Earth, that that which ye deem harmful unto thyself, the very same shall ye be forbidden from doing unto another, for violence and hatred give rise to the same. My command is thus, that ye shall return all violence and hatred with peacefulness and love, for my Law is love unto all things. Only through love shall ye have peace; yea and verily, only peace and love will cure the world, and subdue all evil."

— The Book of Ways, Devotional Wicca

Scientology

The Way to Happiness expresses the Golden Rule both in its negative/prohibitive form and in its positive form. The negative/prohibitive form is expressed in Precept 19 as:

19. Try not to do things to others that you would not like them to do to you.

— The Way to Happiness, Precept 19

The positive form is expressed in Precept 20 as:

20. Try to treat others as you would want them to treat you.

— The Way to Happiness, Precept 20

Traditional African religions

Yoruba

One who is going to take a pointed stick to pinch a baby bird should first try it on himself to feel how it hurts.

— Yoruba Proverb

Odinani

Egbe bere, ugo bere. (Let the eagle perch, let the hawk perch.)

— Igbo Proverb

Nke si ibe ya ebene gosi ya ebe o ga-ebe. (Whoever says the other shall not perch, may they show the other where to perch.)

— Igbo Proverb

Secular context

Global ethic

The "Declaration Toward a Global Ethic" from the Parliament of the World’s Religions (1993) proclaimed the Golden Rule ("We must treat others as we wish others to treat us") as the common principle for many religions. The Initial Declaration was signed by 143 leaders from all of the world's major faiths, including Baha'i Faith, Brahmanism, Brahma Kumaris, Buddhism, Christianity, Hinduism, Indigenous, Interfaith, Islam, Jainism, Judaism, Native American, Neo-Pagan, Sikhism, Taoism, Theosophist, Unitarian Universalist and Zoroastrian. In the folklore of several cultures the Golden Rule is depicted by the allegory of the long spoons.

Humanism

In the view of Greg M. Epstein, a Humanist chaplain at Harvard University, " 'do unto others' ... is a concept that essentially no religion misses entirely. But not a single one of these versions of the golden rule requires a God". Various sources identify the Golden Rule as a humanist principle:

Trying to live according to the Golden Rule means trying to empathise with other people, including those who may be very different from us. Empathy is at the root of kindness, compassion, understanding and respect – qualities that we all appreciate being shown, whoever we are, whatever we think and wherever we come from. And although it isn’t possible to know what it really feels like to be a different person or live in different circumstances and have different life experiences, it isn’t difficult for most of us to imagine what would cause us suffering and to try to avoid causing suffering to others. For this reason many people find the Golden Rule’s corollary – "do not treat people in a way you would not wish to be treated yourself" – more pragmatic.

— Maria MacLachlan, Think Humanism

Do not do to others what you would not want them to do to you. [is] (…) the single greatest, simplest, and most important moral axiom humanity has ever invented, one which reappears in the writings of almost every culture and religion throughout history, the one we know as the Golden Rule. Moral directives do not need to be complex or obscure to be worthwhile, and in fact, it is precisely this rule's simplicity which makes it great. It is easy to come up with, easy to understand, and easy to apply, and these three things are the hallmarks of a strong and healthy moral system. The idea behind it is readily graspable: before performing an action which might harm another person, try to imagine yourself in their position, and consider whether you would want to be the recipient of that action. If you would not want to be in such a position, the other person probably would not either, and so you should not do it. It is the basic and fundamental human trait of empathy, the ability to vicariously experience how another is feeling, that makes this possible, and it is the principle of empathy by which we should live our lives.

— Adam Lee, Ebon Musings, "A decalogue for the modern world"

Existentialism

When we say that man chooses for himself, we do mean that every one of us must choose himself; but by that we also mean that in choosing for himself he chooses for all men. For in effect, of all the actions a man may take in order to create himself as he wills to be, there is not one which is not creative, at the same time, of an image of man such as he believes he ought to be. To choose between this or that is at the same time to affirm the value of that which is chosen; for we are unable ever to choose the worse. What we choose is always the better; and nothing can be better for us unless it is better for all.

— Jean-Paul Sartre, Existentialism is a Humanism, pp. 291–292

Other contexts

Human rights

According to Marc H. Bornstein, and William E. Paden, the Golden Rule is arguably the most essential basis for the modern concept of human rights, in which each individual has a right to just treatment, and a reciprocal responsibility to ensure justice for others.

However Leo Damrosch argued that the notion that the Golden Rule pertains to "rights" per se is a contemporary interpretation and has nothing to do with its origin. The development of human "rights" is a modern political ideal that began as a philosophical concept promulgated through the philosophy of Jean Jacques Rousseau in 18th century France, among others. His writings influenced Thomas Jefferson, who then incorporated Rousseau's reference to "inalienable rights" into the United States Declaration of Independence in 1776. Damrosch argued that to confuse the Golden Rule with human rights is to apply contemporary thinking to ancient concepts.

Science and economics

There has been research published arguing that some 'sense' of fair play and the Golden Rule may be stated and rooted in terms of neuroscientific and neuroethical principles.

The Golden Rule can also be explained from the perspectives of psychology, philosophy, sociology, human evolution, and economics. Psychologically, it involves a person empathizing with others. Philosophically, it involves a person perceiving their neighbor also as "I" or "self". Sociologically, "love your neighbor as yourself" is applicable between individuals, between groups, and also between individuals and groups. In evolution, "reciprocal altruism" is seen as a distinctive advance in the capacity of human groups to survive and reproduce, as their exceptional brains demanded exceptionally long childhoods and ongoing provision and protection even beyond that of the immediate family. In economics, Richard Swift, referring to ideas from David Graeber, suggests that "without some kind of reciprocity society would no longer be able to exist."

Criticism

Philosophers, such as Immanuel Kant and Friedrich Nietzsche, have objected to the rule on a variety of grounds. The most serious among these is its application. How does one know how others want to be treated? The obvious way is to ask them, but this cannot be done if one assumes they have not reached a particular and relevant understanding.

Differences in values or interests

George Bernard Shaw wrote, "Do not do unto others as you would that they should do unto you. Their tastes may be different." This suggests that if your values are not shared with others, the way you want to be treated will not be the way they want to be treated. Hence, the Golden Rule of "do unto others" is "dangerous in the wrong hands,"^[78] according to philosopher Iain King, because "some fanatics have no aversion to death: the Golden Rule might inspire them to kill others in suicide missions."

Differences in situations

Immanuel Kant famously criticized the golden rule for not being sensitive to differences of situation, noting that a prisoner duly convicted of a crime could appeal to the golden rule while asking the judge to release him, pointing out that the judge would not want anyone else to send him to prison, so he should not do so to others. Kant's Categorical Imperative, introduced in Groundwork of the Metaphysic of Morals, is often confused with the Golden Rule.

Cannot be a sole guide to action

In his book How to Make Good Decisions and Be Right All the Time, philosopher Iain King has argued that "(although) the idea of mirroring your treatment of others with their treatment of you is very widespread indeed… most ancient wisdoms express this negatively – advice on what you should not do, rather than what you should." He argues this creates a bias in favour of inertia which allows bad actions and states of affairs to persist. The positive formulation, meanwhile, can be "incendiary", since it "can lead to cycles of tit-for-tat reciprocity," unless it is accompanied by a corrective mechanism, such as a concept of forgiveness. Therefore, he concludes that there can be no viable formulation of the Golden Rule, unless it is heavily qualified by other maxims.

Responses to criticisms

Walter Terence Stace, in The Concept of Morals (1937), wrote:

Mr. Bernard Shaw's remark "Do not do unto others as you would that they should do unto you. Their tastes may be different" is no doubt a smart saying. But it seems to overlook the fact that "doing as you would be done by" includes taking into account your neighbor's tastes as you would that he should take yours into account. Thus the "golden rule" might still express the essence of a universal morality even if no two men in the world had any needs or tastes in common.

Marcus George Singer observed that there are two importantly different ways of looking at the golden rule: as requiring (1) that you perform specific actions that you want others to do to you or (2) that you guide your behavior in the same general ways that you want others to. Counter-examples to the golden rule typically are more forceful against the first than the second.

In his book on the golden rule, Jeffrey Wattles makes the similar observation that such objections typically arise while applying the golden rule in certain general ways (namely, ignoring differences in taste, in situation, and so forth). But if we apply the golden rule to our own method of using it, asking in effect if we would want other people to apply the golden rule in such ways, the answer would typically be no, since it is quite predictable that others' ignoring of such factors will lead to behavior which we object to. It follows that we should not do so ourselves—according to the golden rule. In this way, the golden rule may be self-correcting. An article by Jouni Reinikainen develops this suggestion in greater detail.

It is possible, then, that the golden rule can itself guide us in identifying which differences of situation are morally relevant. We would often want other people to ignore any prejudice against our race or nationality when deciding how to act towards us, but would also want them to not ignore our differing preferences in food, desire for aggressiveness, and so on. This principle of "doing unto others, wherever possible, as they would be done by..." has sometimes been termed the platinum rule.

Popular references

Charles Kingsley's The Water Babies (1863) includes a character named Mrs Do-As-You-Would-Be-Done-By (and another, Mrs Be-Done-By-As-You-Did).

Cosmological Constant and Dark energy

August 22, 2018  

Original link:  https://notsoeasyphysics.blogspot.com/2018/08/cosmological-constant-and-dark-energy.html 

Before we dive into this topic we should learn about Einstein Field Equation.

The Einstein Field Equation, which describes the gravity as a curvature of spacetime

1. Rᵤᵥ - ½Rgᵤᵥ + Λgᵤᵥ = 8πGTᵤᵥ /c⁴

Here

Rᵤᵥ is Ricci tensor which comes from Riemann tensor after, contracting one of the indices.
gᵤᵥ is metric tensor thus defines the surface or geometry
R is ricchi scalar which is trace of Rᵤᵥ
Tᵤᵥ is Stress Energy Tensor (Not Cauzy Stress Tensor)
G is universal gravitational constant(the same one used in Newtonian Gravity)
c is speed of light
Λ is cosmological constant

Here left-hand side is the curvature of spacetime, or gravity and right-hand side is the source term, like charge is the source of electric field and charge causes the curvature in electric field.

But let me write few more equations just to justify that metric tensor is enough to know everything about spacetime.

We use " metric tensor " to define Christoffel symbol

2. Γᵏᵢⱼ=½gᵏˡ(∂ᵢgⱼₗ+∂ⱼgᵢₗ−∂ₗgᵢⱼ)

We use Christoffel symbol to define Riemann Curvature Tensor

3. Rᵏₗₘₙ = ∂ₗΓᵏₘₙ - ∂ₙΓᵏₘₗ + ΓᵏₗₐΓᵃₘₙ - ΓᵏₙₐΓᵃₘₗ

Then, we use Riemann Curvature Tensor to define Ricci Tensor

4. Rᵏₗₖₘ= Rₗₘ

Finally, use it to define Ricci Scalar

5. Rᵤᵤ = R

Enough of that, as you are now familiar with Einstein Field Equation now we can talk some Physics. If we assume that Λ is "0" then, the equation turns to

Rᵤᵥ - ½Rgᵤᵥ = 8πGTᵤᵥ /c⁴

Which is fully attractive in nature, just like Newtonian Gravity is and under low speed and weak gravitation assumption the equation written above turns to

∇²φ = 4πGρ

Which is Poisson's law and g = - ∇φ

Now, we know this much, that General Relativity converges to Newtonian one, under two assumptions, but now let's talk about the Λ term in Einstein Field Equation a.k.a. Cosmological Constant. The sign and value of this term decides the fate of spacetime (that's why physicist often says gravitation decides the fate of our universe) if this term is negative, then in the sense that it could cancel out(as it will add with ricci scalar) and could cause gravitation to vanish and could make universe static. But it turns out the value of cosmological constant is not negative but positive it would reduce the value of ricci tensor. In the expression every term is dynamic(in the sense that, it depends on the scenario) but cosmological constant ain't and that's good as it is responsible for Big Bang.  Let me elaborate it a bit, but for that you would have to accept one thing that if the positive stress tensor makes gravity then, negative stress tensor would make repulsive gravity.

Now, let's modify the equation a bit and assume Tᵤᵥ = 0.

The equation becomes

Rᵤᵥ - ½Rgᵤᵥ + Λgᵤᵥ = 0

Few modifications

Rᵤᵥ - ½Rgᵤᵥ = -Λgᵤᵥ

Now, here Λgᵤᵥ , term act as pseudo stress tensor as this can also cause spacetime to curve, because the curvature depends only on "gᵤᵥ" which affects "Rᵤᵥ" but doesn't affect "Λgᵤᵥ".

So, if I assume, Λ < 0

Then, it would act as normal gravity source but if Λ > 0, then

As R.H.S. is -ve  so L.H.S must also be, which means it acts opposite to attractive gravity as repulsive gravity.

Now, all of these stuff is clear how cosmological constant can change, the fate of gravity, we all know from Inflation Theory that total energy of universe is "0" hence that would make Tᵤᵥ = 0 . But this doesn't affect Λ and hence can cause repulsive gravity even without energy or matter.

Now, we know what is this cosmological constant and how it could drive the expansion of our universe. But let's talk about Dark Energy, this is the most mysterious form of energy, as it drives the expansion rate of our universe, its just a name given to cosmological constant (in a sense). I haven't told you the whole glory detail but that would make you board, so I am gonna just tell you, there is an equation known as Friedman Equations, whicj involves the cosmological constant and it describes the acceleration of universe on the basis of value of cosmological constant long but some other parameters.

Thanks
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