OPINION: Economists understand greed very well; after all, the urge to get rich is our discipline’s main explanation for human actions. Economists further recognise that greed can be good. When our greedy urges are constrained by institutions, so that we compete with each other by means of specialisation in production rather than by killing or cheating one another, our economies produce growth.

But the phenomenon of love has flummoxed us economists. We have followed much of the rest of society in seeing love as something that is a cosmic accident: neither predictable nor manipulable, love has been thought to arise mysteriously. Once finding himself by chance in love, a person suddenly cares about more than just himself. It is allegedly by happy accident that people love their children, their spouses, the constitution of their country, and many other people and constructs.

In our new book, An Economic Theory of Greed, Love, Groups, and Networks, we behold and treat love in an entirely different way. It would be fair to say that we take the stance of aliens looking at humans as just another species, with love merely one behavioural strategy available to that species. Blasphemous as this may sound, our goal is to apply the scientific method to the realm of the heart.

At the most basic level, we contend that love is a submission strategy aimed at producing an implicit exchange. Someone who starts to love begins by desiring something from some outside entity. This entity can be a potential sexual partner, a parent, “society”, a god, or any other person or abstract notion.

From a position of relative weakness, the loving person tries to gain control over this entity by incorporating the entity into his own sense of self. Of many examples, that of the child is perhaps easiest to see in this framework: a weak infant starts to love the parents who provide for his needs, and starts to see himself as part of the family. We contend that the same fundamental process explains why men and women start to love their partners, their countries, their jobs, and their gods.

The consequences of this basic mechanism are immense for any human organisation. Without it, there could be no families, no religions, no science, and no countries, because the loyalty of those who love is part of what keeps families together, soldiers loyal, scientists truth-seekers, and the religious faithful.

Naturally, within any group, not everyone loves to the same degree, and in fact many members of groups do not love at all and instead merely pretend to share the group ideal. But without any real love, created when lovers are weak and needy, human organisations would fall apart and our economies would cease to function.

There is much more to say about love: how it conferred an individual evolutionary advantage long ago; how the neural mechanisms responsible for it relate to our cognitive and non-cognitive development throughout life; how to define weakness and how to describe human desires; how “love” relates to other difficult concepts that economists have long struggled with, such as “power” and “networks”; and, most excitingly, what steps lead from this essentially individual mechanism to the highly organised societal structures we see today. We explore all of these paths in our book. We argue that love is a vital element in almost everything that is important to economists and social science, from why people by and large pay their taxes to why they are able to work happily together in teams.

Why did we decide that love had to have something to do with economics? Because reality forced us into acknowledging the importance of love. If you want to understand yourself and your society but are prepared to make no mental space for love in your explanations, then all we can say is good luck. We hope you have more success than we did. For more than 10 years, we independently worked on understanding society without an explicit role for love, and we basically got stuck. It took us another 10 years to develop our best guess for how love relates to greed and to all of the complexities of humans and their societies.

Finally, why do we see the discipline of economics as the natural home for our theory of love’s genesis and consequences? Because economics offers an extensive discourse on the other crucial ingredient propelling human action – greed – and also because economics is a science whose nature and ideal is to offer simple stories to capture social complexity. By combining love and greed to construct a simple, tractable model of our social world, we hope to have advanced the discovery of what humans and their societies are all about.

Gigi Foster is a Senior Lecturer in Economics at the Australian School of Business, UNSW. Paul Frijters is a Professor of Economics at the University of Queensland.

An Economic Theory of Greed, Love, Groups and Networks, by Gigi Foster and Paul Frijters, is published by Cambridge University Press.

This opinion piece was first published on The Conversation.