Escalation is the other side of settlement, and negotiation links them together. To escalate means to increase by steps, referring to the dynamics of conflict. A party escalates – thus transitively – to hurt the opponent and make it change its behavior, either entirely (to give in) or partially (to negotiate). It may also escalate, less instrumentally, simply to retaliate or to punish, without any particular purpose in terms of making the opponent do something. In either case, it raises the opponent's cost of holding out or of seeking to win. In the process, it probably also raises the cost for itself, since escalations are generally not cost free to the escalator. It may continue to escalate on its own in this way, “turning the screws” on the opponent (to change the metaphor) until the latter changes its behavior in the conflict. In the simplest case, the party continues to escalate until it can go no further, either until the costs (or the depletion of resources) of escalation outweigh the benefits it seeks to obtain or until the opponent changes its behavior.
More likely than one-party escalation is for the opponent not to simply hunker down and resist, but to escalate in reaction, for a double purpose – to retaliate or halt the first party's escalation and to make the first party change its behavior in turn and give in or negotiate. Then escalation becomes a two-dimensional spiral – one is tempted to say “a double helix” – and the parties’ calculation becomes more complicated.