What is the nature of societal conflict, then? If we are a necessarily altruistic society and have achieved our vaunted status because of this idea of helping others for mutual gain, why do we fight? That is to say, why does war seem such a persistent characteristic of humanity?
At the basic level, conflict stems from limited resources and apparent inequity in their distribution.
A good example of a basic resource is food, since everyone needs to eat to survive. Food is limited because we receive a certain amount of energy from the sun and the entire ecosystem is competing for that energy. Humans, like other species, need at least a particularly-sized portion of that total in order to survive. If I don't maintain a certain number of calories per day, my body will eventually be unable to maintain itself and I will die. Thus, my instinct to obtain the minimum required amount of food is very strong. When I and those around me have plenty of food then there is no perceived need to fight over it, so the inherent limit of a resource is an important factor.
A critically limited resource does not by itself conflict create, however, as conflict is only worthwhile if there are clearly apparent potential gains. Say there are one hundred apples in the world to feed two people, but only one of these two people knows this and this same individual is in possession of ninety-nine of the hundred apples. The other individual, lacking complete information, will assume his apple is the only remaining apple on the planet, eat it, then fade away in search of food without ever coming into conflict with the other person. Only once the inequity of the resource is made apparent, imagine these two people now within sight of each other, does conflict become a rational response.
The whites of human eyes are much more prominent than in all other species with this part of the eye (called sclera), which biologists suggest has allowed us to follow the gaze of other humans with far greater accuracy. Knowing what someone else is looking at, say the big pile of juicy apples behind you, is critical to understanding their intentions. Recognizing that both you and the other want these apples because you are alike and both need food is shared intentionality. (Tomasello et al.)
Human evolution and the notions of justice, equality, and morality rest on our ability to sense and predict the emotions and intentions of our fellows. In the apple metaphor, one can imagine two likely outcomes once the two persons are aware of each other and can interact: the two come to a shared understanding that fighting is not necessary and can see how cooperation may be productive for both of them individually, or they do not come to a mutual understanding and clash physically for control of the food supply. The direction this tense situation tips is determined by the mental and communicative capacity of the participants.
Empathy and our ability to understand a shared intentionality (survival) are predicated on the idea of being able to sense inequity. When the "have-not" person in the scenario above sees the pile of apples behind the "have" person, the have-not with only one apple will recognize that the have individual has not only enough food for himself, but an excess of food in general. If the have and the have-not are able to empathize, perhaps first using only body language, facial cues, and other non-verbal communication, it is possible for each to understand the needs of the other and recognize the value in working together, rather than simply fighting as a first and foremost response.
Humans are especially distinguished in that our brains allow us to take shared intentionality and better imagine likely outcomes. Two monkeys aware of the last pile of apples might recognize that both of them want the apples and instinctively act physically to gain control, but a human mind has the capacity to stop and imagine a better scenario. The person with all the apples acknowledges that the apples need to be protected physically if necessary, but unlike other animals may also realize that offering some apples to the have-not might mean two cooperating defenders instead of just one. If the have and the have-not can communicate and reach a mutual understanding of this idea, physical conflict may be rationally delayed for a more appropriate time and constructive cooperation can occur in the meantime.
This kind of predictive thinking is continually evolving, allowing humans to advance beyond hunting groups into settlements, cities, nation-states, countries, a global United Nations. At each level, the factors that determine whether conflict will occur remain the same. Extending the apple metaphor, imagine, instead of a hundred apples and two people, a single warehouse of 10,000 apples and two separate groups of 1,000 people each. Both groups will make an assessment based on the information they can gather, including anything intentionally communicated (diplomacy), then decide on an appropriate course of action. If the have group, in control of the apples, is not convinced that the results of cooperating with the have-not group are better than the results of defending absolute control of the resource, physical conflict (battle) ensues.
Conflict is Constructive
Assuming both groups are of equal strength they are not likely to annihilate each other in one altercation, so each group continually reassesses their course of action. Losses are the most painfully obvious new information. If neither group is dominant enough to eliminate the opposing group, over time it becomes clearer to everyone that conflict only weakens both groups as casualties mount (war weariness). A peaceful arrangement is reached that dictates resource allocation in mutually acceptable terms. Though both sides are now weaker than they were before, an important correction was made to their society as a whole: the group in power no longer dominates, but cooperates.
Whatever factors led to the defensive position of the power group, perhaps an authoritarian leader and incomplete intelligence, are mitigated by the destructive act of war itself, such that the now combined community can progress beyond mutually destructive conflict and embrace the value of greater cooperation. Conflict is necessary for progress because it is corrective, ultimately reallocating resources more equitably and enabling constituents to contribute cooperatively.
“Warfare is ultimately not a denial of the human capacity for cooperation, but merely the most destructive expression of it.” -Lawrence H. Keeley, War Before Civilization