What are social norms and how do they influence our behaviour?


To ask a human what and how influential social norms are, is a little bit akin to asking a fish: What is water and how does it affect you? The difference: fish seem to honour the old latin proverb si tacuisses, philosophus mansisses and don’t embarrass themselves by trying to answer.

Humans are ultra-social beings, with a capacity to transmit masses of adaptive information, including norms (cf. Joyce 2007, p.40). Thus, from birth, we are completely submerged in norms. Most of the time we are unaware of them – sometimes even denying their existence (cf. Binmore 2010, p.143).

As norms are deeply ingrained in our lives, yet constantly changing, they are hard to study. Moreover, there are even meta-norms governing discourses on norms. In particular, religions and ideologies often advocate against objective inquiry into the nature of norms (cf. Binmore 2011, p. 2) – sometimes going so far as to justify the killing of critics, as the Catholic Church did in the past and some schools of Islamic jurisprudence still do (cf. Fitzpatrick & Walker 2014, pp. 64-67). This isn’t surprising, since these actors base their authority on their claim to superior moral insight (cf. Binmore 2011, pp. 1 -2).

Consequently, there isn’t a consensual theory of the nature of norms among philosophers, psychologist and scientist yet (cf. Dubreuil et al. 2013, p. 137).

In this essay I outline a game theoretical approach to the objective study of norms. In doing so, I try to answer the question: What are social norms and how do they affect our behaviour?

2. A Definition

Norms are understood as a kind of grammar of social interaction: systems of rules specifying right and wrong (cf. Bicchieri et al. 2023, p.3). When a norm exists, people have a conditional preference for certain behaviour based on their empirical and normative expectations (cf. ibid. p.7). These expectations form an invisible consensus, which coordinates interaction and induces people to punish or reward others for certain behaviour (cf. Bendor & Swistak 2001, pp. 1493-1494) Punishment may range from mild e.g. subtle scorn, to severe like killing (cf. Binmore 2011, pp. 3 -4). Norms are therefore self-enforcing at the group level (cf. Young 2015, p.5).

3. The Scope

There’s no consensus on the scope of norms. While some research suggests a cross-cultural norm already present in children, to distinguish norms (cf. Joyce 2007, pp. 138 – 139), other research indicates that the distinction between e.g. moral and non-moral norms may be based solely on the perceived seriousness of transgression (cf. Dubreuil & Grégoire 2012, pp. 149 – 151; cf. Binmore 2011, p. 3). For the sake of a general argument, this essay takes the latter, broader approach, grouping together all types of norms – e.g. formal, informal and moral – as social norms.

4. The Origin

The question of the origin of norms – or their genealogy – is important, as depending on the answer, people tend to infer a lot about their nature. This question may seem innocent in relation to most norms, e.g. manners; and is often quickly answered by citing convention – although even bad manners can be punished by death in some cultures and times (cf. Clifton 2018; cf. Binmore 2011, p.3). The question becomes thornier when we look at the set of norms labelled moral.

As to the origins of more strictly enforced norms such as morality, religious authorities like to point to commands from a god or gods. Supposedly enlightened thinkers, on the other hand, like to use counterfactual thought experiments or some more or less metaphysical principle as an axiomatic primitive. But these explanations seem insufficient to explain the empirically observable great diversity of norms, as well as their dynamism (cf. Joyce 2011).

When priests, ideologues or ethicists talk about norms, they often do not seem to be talking about our world, inhabited by real people and governed by real norms, but about a platonic fantasy. Absolute and eternal universal norms can’t be found outside of books and declarations. Most of these writing can be even interpreted as just individuals trying to prove their own preferences as binding on everyone else (cf. ibid.). Some scientists don’t fare much better – taking norms for granted without asking why and how they came about or behaving like secular priests and propagating their own normative views (cf. ibid; cf. Bendor & Swistak 2001, pp. 1495).

The orthodox normative discourse is a disappointing spectacle, millennia of spilled ink and wasted compute (cf. Joyce 2011) – as the question how one ought to behave is the wrong question to begin with (cf. Binmore 2011, p.1). If we want to understand norms and adopt better ones, we need to step out of the water and ask: why and how did normativity emerge?

From a naturalistic position the answer is to be found in evolution. After all, humans are the result of at least 3.5 billion years of biological (cf. Arnoldt 2015) and thousands of years of cultural evolution. Our behaviour today – while itself not necessarily adaptive – is the product of psychological mechanisms that developed through genetic, cultural, and individual adaptions (cf. Joyce 2007, p.5).

Our belief in norms, and our desire to enforce them, seem to be innate traits of human nature. Innate in the sense as e.g. fear is an innate trait: the capacity for fear is present in all but brain-damaged humans, but the content of our fears seems to result mainly from the environment (cf. Joyce 2007, pp.6-8). Similarly, a predisposition for normative thinking, a moral faculty, appears to be hard-wired, while the content is highly malleable. This is why the search for eternal moral truths has been so fruitless in millennia of religion and philosophy:

The psychological mechanisms behind norms are not the result of divine sparks, but of the human brain, whose high plasticity allows us to adapt more quickly to a wide variety of environments than the slow grind of purely biological evolution (cf. ibid.). Since normativity is the result of our adaptation to changing environments, it should come to no surprise, that as environments change, so do norms.

5. Norms and Evolution

Evolution doesn’t seem to select for Plato’s idea of the good – but if this is the case, how could social norms – especially those that lower fitness – be the result of evolution? Entire books have been written on this subject. To discuss all mechanisms and concepts – e.g. kin-, group- and sexual-selection, indirect reciprocity etc. – in detail is beyond the scope of this essay. Therefore, I will just outline three key problems that seem fundamental as they are solved by normative faculties:

5.1 Cooperation

How can stable cooperation among rational actors be possible, despite conflicting interests (cf. Bendor & Swistak 2001, p. 1500)?

Consider a small Stone Age tribe roaming the savannah. Suddenly a lion emerges from the tall grass and attacks them. For the sake of simplicity, let us assume each tribe member has two options: Run away or throw a stone at the lion. If everyone throws stones the lion will probably flee, and no one will die. However, if some run away, the lion will certainly eat one of the stone-throwers, while the runners have a high probability of escaping unharmed.

What is the rational decision for an individual in this single encounter? Run away. Because if others run away, you don’t want to be left alone with the lion. The Nash equilibrium in this single game is to run – if they are rational and prefer their own survival, everyone will run. The lion snatches someone, but the odds are it isn’t you.

But: This single event isn’t all. If such encounters repeat and each time all run away and each time the lion snatches someone, over time, the tribe will get smaller and smaller. Eventually the tribe and its genes vanish. Individual rationality caused collective tragedy – a classical dilemma from game theory (cf. Binmore 2011, pp. 57 – 62).

How could this dilemma be solved by making it rational to throw stones? The payoffs must change so that running away is more costly than staying and risking death. Here norms come into play: If a group adopts a norm to denounce fleeing and selfish individuals as unreliable cowards and egoists, and subsequently denies them access to resources and reproductive sex, the Nash equilibrium shifts closer to cooperatively throwing a stone. This can be further encouraged by harsher norms affecting kin, e.g. the norm to kill the children of fallen men – which has been observed in tribal societies (cf. Buss 2016, pp. 79, 140). In the absence of a modern police force with surveillance and forensics, telling people the lie that they are being watched by an all-mighty God may make cooperation even easier – and become a useful fiction branded as the absolute truth of religion (cf. Joyce 2011).

The capacity for norms facilitates cooperative behaviour and, in the long run, rises the fitness of a group. Since the long-term reproduction of one’s own genes depends on the long-term fitness of one’s group, individual fitness increases too (cf. Joyce 2007, pp. 33-40). While some behaviour e.g. altruism, may appear irrational or selfless, it can be in fact fitness-advancing. Normative thinking doesn’t seem to be the result of some insight into an idea of the good, but the result of a trick evolution has played on our species, a noble lie we tell ourselves to facilitate cooperation and increase fitness.

But: while our capacity for norms is the result of adaptation and adaptive itself – this doesn’t mean, that all norms are adaptive. Our normative faculties are – like all cognitive faculties – not immune to failure and abuse. To believe norms as truths may be advantageous in many scenarios, but it can also lead to collective self-destruction e.g. mass-suicides. Furthermore, rational agents not only have preferences to adhere to established norms, but also to manipulate the existing consensus towards norms, which are more beneficial to themselves. From the populist demagogues of ancient Athens and today, to the medieval indulgence trade, to oil companies denying climate change, to NGOs using moral outrage and fearmongering to raise funds etc. etc. examples of normative (self)deception abound.

5.2. Equilibrium Selection

Interactions can have several different Nash equilibria. E.g. it is rational, that all cars should drive only on one side of the road, to ensure safe traffic. But should they drive on the left side or on the right? Both solutions are equally rational and efficient. In such cases social norms act as equilibrium selection devices, dictating which solution people adopt (cf. Binmore 2010, p.142).

5.3. Bounded Rationality

Human rationality is bounded – we don’t have the time, nor the certainty nor the cognition to calculate the rationality of all our decisions (cf. Hayakawa 2000, pp.4, 6). We have to rely on heuristics. Following norms deontologically can serve as such a heuristic, facilitating faster and better decisions. Social norms are sources of low-cost heuristics, as just imitating what others do successfully saves precious resources (cf. ibid. pp. 7 – 9). Even mundane things like fashion or dietary choices, are therefore heavily influenced by norms (cf. Binmore 2010, p. 141).

6. Conclusion

I have roughly outlined the nature of norms, as well as their primary functions, as they can be explained by evolutionary game theory:

Social norms are the result of psychological mechanisms, which developed as an evolutionary adaptation. They work as consensual expectations among members of a group to adhere to rules, enforced through punishment and reward, facilitating cooperation and acting as equilibrium selection devices and low-cost heuristics, influencing our decision-making in almost all areas of life.

A full elaboration of this view of norms, as well as its implications, must be further explicated in subsequent writing.

3 of 4 Essay for the course: Rational agents in social interaction

Grade: 1,3 (Very good)

Lecturer: Dr. Jurgis Karpus

LMU University of Munich



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