In the European Union, the number of new marriages has been nosediving for years, while divorces are on the rise. When long-term relationships between couples fail and family ties are loosening and declining in importance, a vacuum is created from which friendships might possibly benefit. After all, friends can look after each other just as well as spouses, can't they? But can we justifiably expect friends to provide this kind of support? Janosch Schobin has looked into the subject for us.

Self-interest plus deep affection – is that a contradiction in terms? Or could the two be compatible in a relationship between friends?
Viewed historically, the idea that a friendship should not be tied to a specific purpose – and that we should distinguish between friends and business associates – is relatively new. It dates back to the Scottish Enlightenment during the 18th century. In everyday life today there is little distinction between friendship and personal benefit: people might well lend money to their friends etc. But we tend to be less flexible when it comes to the opposite case: there is broad agreement that people should not foster friendships for the sole purpose of potential advantages. And that consensus is universal. An international survey once asked whether making friends for practical gain was acceptable. It was a genuinely global study that involved respondents from 28 countries – including South Africa, Japan, New Zealand, Europe, Chile, and the United States. There was little support for the idea, particularly in more affluent societies. And that makes absolute sense. If your personal circumstances render you dependent on others for help – because, for example, your country doesn't provide it – then you are somewhat more likely to engage in friendships that can offer real and practical benefits.

But aren't all friendships fueled by self-interest? After all, friends are about more than having fun.
Our friends naturally play key roles in our lives and livelihoods. Since the Classical period, discussions of the ethics of friendship have focused on mutually dependent relationships. Often this has been symbolized by two warriors standing back to back; they can only survive if they defend each other and neither lets the other down. In short, people can only survive if they support one another, and they need make constant sacrifices to achieve this end. That's the big picture. Embedded within this is the quality that defines friendship: that people expose themselves to risks for others and protect them from existential threats that they cannot defend themselves against alone. The question, however, remains: is this image still relevant in our modern-day world? In my view, the answer is yes. To the extent that our lives are no longer predetermined by being a member of a social class and being embedded within a social structure. Put differently, to the extent that we are free to choose and channel our own lives, the question arises: how can I achieve this? What are my options? And people seek their answers in discussions with friends, who therefore play important roles as advisors and capable points of reference. Put bluntly, almost everyone is blind to some aspect of themselves. For example, some view themselves as extremely modest but are in fact full of themselves, or they think they are good listeners but in reality miss half of what is being said. Friends are important here because they gather information about us that we do not register ourselves. And by sharing this information they allow us to manage our lives better. What do I want in life? What motivates me? We need friends when these questions arise, friends who help us understand ourselves.

Put differently, our friends strip away some of the illusions we harbor about ourselves. Do we like that? Do we really want it?
Statistics show that our willingness to enter into close friendships has increased marginally within our society in recent years: since the mid-1980s there has been a slight rise in the number of people who have at least one close friend with whom they discuss matters of personal importance. Overall, however, the figure is fairly low: about one in every three people in Germany. In this context people are often asked who they would accept uncomfortable truths from. In this respect, the proportion of people who can provide a name has remained stable, at least over the past 10 years. Exactly how this pans out in practice is interesting, because it varies significantly from relationship to relationship. I myself have friends who can tell me anything they want, but there are other people who don't like this up-front approach. For this reason, friendships always develop their own individualized forms of communication, i.e. one party knows how to package potentially awkward information so the other can deal with it. There are epiphanies in relationships when people learn something revealing about a friend. To cope with these moments, friends develop a sensitive manner of discussing weaknesses and vulnerabilities without having to mention them explicitly. They adopt a secret code of sorts that prevents outsiders from understanding these private conversations.

Perhaps we need this type of encrypted communication because it makes it easier to talk about our needs and to 'expose our flanks' to others.
Psychologically speaking that is undoubtedly true. Friendships are built by individuals who disclose their vulnerabilities to each other. That said, the majority of friendships aren't particularly intimate; rather they are linked to individual aspects of life. As a result the vulnerabilities themselves are limited, making them easier to bear. The trickiest situations arise in really intimate friendships, because it is always difficult to lay ourselves open to criticism. That's part of a learning curve. But, conversely, people need the ability to lighten the load on their friends, making it easier for them to lay bare their most private concerns.

If friendships are beneficial and help us manage our lives, should I not be looking for younger, fitter friends when I reach middle age so that they can help when I grow old and frail?
In practice, thinking like this possesses a certain logic because personal care usually only becomes a factor during people's advanced years. But friends are often roughly the same age. And that leads to a problem that aging spouses face as well: that they grow old and needy together. A significant age difference is needed to circumvent this drawback. However, caring for somebody isn't straightforward, with women typically playing the leading roles. Frequently men have no idea or experience when it comes to caregiving. So if men want to care for each other, remembering that most friends of men are themselves male, there are fewer people available with the know-how required. Women, by contrast, are better placed: their close friends tend to be female. A further problem lies in the fact that friendships are ultimately keyed to ensuring independence. And care does not fit within this mold. Care during old age is usually irreversible and one-sided, i.e. most likely I won't be able to repay the care I am getting in kind, at least not to the initial caregiver. Nevertheless, anyone familiar with the inside of a retirement home will know how important it is to think ahead.

That being said, friends of significantly different ages aren't exactly the norm.
Moreover, they are particularly rare in very close friendships. But personal care is an extremely intimate activity, which is why spouses tend to be more acceptable than offspring or friends. The ways in which we find our friends are simply not suited to encouraging intimate friendships between people of different ages. At school and college we are kept together with contemporaries, and the workplaces that subsequently swallow us aren't really conducive to forging close personal relationships.

And isn't it also true that people of different ages aren't typically kindred spirits, and that a degree of similarity is essential to close relationships?
For the most part, friends really are similar. However, this begs the question: "Was that always the case or do they become assimilated after they meet?" We know that both happen, for example that there are mutual affinities between people from similar locations, social classes and economic backgrounds. Acquired and variable parallels such as political persuasions, eating preferences and musical tastes are also strongly influenced by friendships. In short, similarities between friends can be attributed to the process of friendship itself – and here age differences no longer really count.

Is there something like a core component of friendship, something that is a shared feature of all friendships everywhere? Are there certain universal requirements that are common to every culture?
The basic format of a friendship is always the same. People impart information that exposes them or makes them vulnerable in some way. Since the Classical era, this has been THE bonding mechanism that has underpinned friendships everywhere. It transcends borders, time and space. The differences lie in how we create this mechanism and which sacrifices we offer to make. In olden times blood, as the home of the soul, was the badge of honor, and that has remained the case throughout European history. The symbolism is always the same: we can only survive together, I will expose my vulnerability for your sake, and you expose your vulnerability for mine. So the types of friendships people forge are always conditioned by their circumstances in life and the individual risks these entail.

Are there any obvious pitfalls that destroy friendships?
Often a breach of confidentiality is the cause. Yet even more frequently, friendships simply become dormant. Not all of them are designed to last forever; they need repeated rituals to sustain them. In practice, that means that friends need to discuss private matters and expose vulnerabilities and intimacies on a regular basis – if they are to keep a relationship afloat. Friendships are not, however, the primary structures of society, the structures that define our lives. As one example, they aren't generally as important as our careers. Many people would relocate for a job, but not if a friend moves away. In this way the friends part company and their friendship dies. However, I could imagine that this changes something. Giving up a community of friends and setting up home with a partner somewhere else can open up a Pandora's Box. It might, for example, eliminate some of the social props that have sustained a romantic attachment, causing it to fall apart. Lots of things in life are organically interconnected. We know, for instance, that one divorce can frequently spark a domino effect among a wider circle of friends. For this reason, people should think twice about risking their social network for a supposedly practical benefit like a higher salary. I wouldn't recommend doing so beyond a certain age; that might sound overly normative, but it’s my personal perspective.