Between stimulus and response there is a space. In that space is our power to choose our response. In our response lies our growth and our freedom.Viktor Frankl — as attributed
Locus of control is psychologist Julian Rotter's term for the degree to which a person believes their outcomes are determined by their own choices and efforts (internal locus) versus by external forces — luck, fate, powerful others — beyond their control (external locus). It is one of the most studied and most consequential concepts in personality psychology, with effects on health, achievement, persistence, and resilience documented across hundreds of studies.
People with an internal locus of control believe that what they do matters — that their effort, skill, and choices are the primary determinants of what happens to them. They take more initiative, persist longer after setbacks, seek more information before making decisions, and tend to be healthier physically and psychologically. People with an external locus of control believe that outcomes are largely determined by forces outside their control — and this belief, regardless of its accuracy in any particular case, tends to reduce the effort they invest, because effort seems unlikely to make a difference.
The connection to Epictetus's dichotomy of control is direct: the Stoic framework is, in psychological terms, the systematic cultivation of internal locus of control in exactly the domains where it is genuinely applicable, combined with the acceptance of external forces in the domains where they genuinely cannot be controlled. The error of excessive externality is the belief that more is outside one's control than actually is. The error of excessive internality is the belief that everything is within one's control — which sets up for blame, shame, and the exhaustion of trying to govern what cannot be governed.