This paper examines Herodotus' use of words of the ἀνάγκη family in order to determine which external or internal constraints the historian represents as affecting the causality of events. M. Ostwald's Ἀνάγκη in Thucydides (1988) provides a foundation for examining the more restricted application of these terms in Herodotus (85 occurrences vs. 161 in Thucydides). In Herodotus, divine necessity (absent in Thucydides) refers to the predictable results of human wrongdoings more often than to a force constraining human choices. This represents an especially ambiguous Herodotean category, however, and is expressed by a wider range of terms than those with ἀνάγκη-stems. The analysis of natural ἀνάγκη yields more clear-cut results. (1) In Herodotus (and not in Thucydides) ἀνάγκη often qualifies an aggressive compulsion applied by a personal agent. (2) Victims of this despotic ἀνάγκη are partially excused, but those who resist it earn Herodotus' praise. (3) Most importantly, Herodotus (unlike Thucydides) never in turn applies ἀνάγκη words to circumstances that motivate imperialistic actions, especially starting a war. (4) Whereas in Thucydides agents are ‘compelled’ to act also by fear and other internal impulses, the only psychological factor to which Herodotus applies ἀνάγκη words (and this time mostly in a positive sense) is moral obligation.
Herodotus' concept of ἀνάγκη is moralistic, and consistent with his unwillingness to justify imperialism, his practice of assigning responsibility, and his high regard for nomos, on the one hand, and freedom on the other. The narrator's involvement in these principles is reflected in Herodotus' use of ἀνάγκη terms in self-referential statements of the type ‘I am compelled/not compelled to say x.’ These statements represent the narrator as the opposite of an imperial subject and analogous to the most admirable of his characters on the receiving end of compulsion. He is a free agent, who disregards political pressure and is exclusively compelled by the rules that apply to him as researcher and truthful recorder.