The Dichotomy of Control separates what is yours to control from what is not.
A traditional term, Chapter 13 of 30 Philosophers defined it like this:
“Dichotomy of Control is the idea that things are either within your control, or not.”
You may not control the weather, the past, another person’s mood, or the final outcome of a difficult conversation. But you can usually control your preparation, words, restraint, effort, and next action. Before reacting, ask:
What part of this is mine to govern?
The Dichotomy of Control works for both personal and group decisions. The moral agent is active throughout. In Step 1 of the TST Ethical Roadmap, the agent listens to Group Ethics—laws, policies, customs, rights, duties, and shared standards—and also clarifies what is actually under their control and authority.
Historically, the Dichotomy of Control is best remembered through Epictetus and later Stoic practice. Its core insight has traveled far beyond ancient philosophy. A modern echo appears in recovery culture through the Serenity Prayer:
Accept what cannot be changed, change what can be changed, and seek the wisdom to know the difference.
Within TST Ethics, there are only two categories: your control or not. Influence is not a third category. You may not control another person’s decision, but you can often persuade, request, negotiate, model, protest, vote, set boundaries, or withdraw. Those are actions you control. The final choice of another person is not.