One of the most mutually beneficial states that two people can achieve is symbiogenesis, where they take such pleasure in each other’s happiness (and displeasure in each other’s unhappiness) that they start viewing each other’s interests almost as their own. The more strongly this happens, the closer the pair is to being a single, two bodied organism, working towards a common set of goals.
One remarkable benefit to such a state is that it allows for a level of optimal allocation of resources that can be otherwise difficult to achieve. If there is one cookie left on the cookie tray, the member of the pair who enjoys that type of cookie more will take it. The other will be pleased, knowing that more pleasure will be had by his partner than he would get if he ate it himself. And even if this last-cookie-on-a-tray situation occurs ten nights in a row, the same total happiness maximizing result will occur, with the member who benefits most eating the treat each time. No negotiation of “if I let you have this cookie, what will you do for me later?” need occur, and so the optimal result (from the point of view of maximizing total benefit) is achieved even when tit-for-tat exchanges aren’t possible.
A more striking example occurs when one member of a pair becomes needy for a long period of time. This could be due, for instance, to sickness or mental illness. With something approaching symbiogenesis, the non-sick member will be there to help the sick member, which likely maximizes the sum of the utility of both parties. This state may be hard to attain for selfish actors: the non-sick member of the pair could calculate that the cost of helping is not worth the benefits to himself, or that these benefits could be still achieved without making such a large sacrifice. He might choose to abandon the sick member altogether, or to only put in a minimal effort to maintain the relationship until the sickness passes and the relationship again becomes selfishly beneficial.
If you were given the choice to enter into symbiogenesis with another person, would you? It might seem problematic that you could end up sacrificing yourself for the other person (and, in fact, that you would want to do so, if such a sacrifice helped the other person enough). But, the other person would also sacrifice themselves for you. You would sit with them while they were sick, but you would also be taken care of when you are sick. You would miss out on the oatmeal raisin cookies, which are her favorites, but would get more chocolate chip cookies, which are yours.
Given the highly social nature of our species, and the fact that people have different skills and preferences, two people are usually better at achieving two people’s goals than one person is at achieving his own. Two people can provide each other with the basic human needs of love, companionship, physical contact and conversation that a person cannot provide himself. The member of the pair who is better at job interviews can help the other one prepare for them, and the member who is a great cook can share his meals. The member of the pair who is more socially skilled can help the second solve his social problems, while the one who is more financially savvy can help the first make better investment decisions. Plus, both parties can feel safe, and protected, knowing that the other member of their pair is looking out for them unselfishly.
For all its benefits, symbiogenesis can be dangerous when one side of it is faked or faulty. If another person’s happiness makes you happy, but yours does not do the same for him, you are in danger. You will probably start to sacrifice and give, while that person is likely to benefit from your generosity and take. The more the other person gets used to taking, the more natural it will seem to him to do so. You will be risking sitting by someone’s bedside for months when they are very sick, without simultaneously being assured of someone sitting by yours if you need it. Half-symbiogenesis can be extremely damaging. So when you notice the state of symbiogenesis forming, you need to be cautious, making sure that neither person’s feelings of aligned incentives are developing substantially faster than the other. If the feelings develop in near synchrony, the pair will remain protected, and the arrangement will have the best chance of being mutually beneficial.
Some people use a marriage contract as an attempt to force some of the benefits of symbiogenesis. Duty, and social pressure tell us that if our husband is sick we are supposed to take care of him, even if it has become unpleasant to do so. And that we are supposed to earn enough money to make our wife comfortable, even if we hate our job. Marriage contracts, like symbiogenesis, reduce people’s fear of being alone, unprotected, and unloved. Ideally, marriage actually contains symbiogenesis, so that the couple takes care of each other not because they feel like they must, but because it makes them happy to do so. So help is given happily, not begrudgingly.
To help maximize happiness and minimize risk, symbiogenesis should be a goal of ours in our romances, friendships, and familial relationships. We should try to cultivate genuine pleasure in the pleasure of those we like when they are willing to do so for us as well.