Fighting, both defensive and aggressive, has so close a connection with the more generalized self-assertive tendency that it might be included under that instinct. It may be regarded as a special form of self-assertive behavior, often complicated with the emotion of anger.
Self-assertion.
What then is this wonderful instinct of self-assertion, to which fighting and much of laughing are subordinate? "Assertiveness", "masterfulness", and the "mastery impulse" are alternative names. Of all the native tendencies, this is the one most frequently aroused, since there is scarcely a moment of waking (or dreaming) life when it is not more or less in action. It is so much a matter of course that we do not notice it in ourselves, and often not in other persons; and even clever psychological observers have seemed entirely blind to it, and given it no place in their list of instincts.
Self-assertion, like fighting, has two forms, the defensive and the aggressive, and in either case it may be a response to either people or things. That gives four varieties of self-assertive behavior, which may be labeled as follows:
1. Defensive reaction to things, overcoming obstruction, putting through what has been undertaken--the success motive.
2. Defensive reaction to persons, resisting domination by them--the independence motive.
3. Aggressive reaction to things--seeking for power.
4. Aggressive reaction to persons--seeking to dominate. We will take these up in order, beginning with the most elemental.
1. Overcoming obstruction. The stimulus here is much the same as that which induces fighting, but the response is simpler, without anger and without the impulse to do damage. Take hold of a baby's foot and move it this way or that, and you will find that the muscles of the leg are offering resistance to this extraneous movement. Obstruct a movement that the baby is making, and additional force is put into the movement to overcome the obstruction. An adult behaves in a similar way. Let him be pushing a lawn-mower and encounter unexpected resistance from a stretch of tough grass; involuntarily he pushes harder and keeps on going--unless the obstruction is too great. Let him start to lift something that is heavier than he thinks; involuntarily he "strains" at the weight, which means that a complex instinctive response occurs, involving a rigid setting of the chest with holding of the breath, and increased muscular effort. This instinctive reaction may be powerful enough to cause rupture.