This thesis argues that Herodotus should be considered in the context of early Greek science, and in the history of the development of Greek speculative thought in general, not only because of the range of his interests which includes questions about the causes and processes underlying natural phenomena but also because of his methodological self-awareness in tackling these problems. Specifically, he is concerned with the problem of how to make plausible inferences about what is unknown as well as what constitutes an adequate causal explanation. He is more polemical and engages critically with second-order questions more often in his ethnographic accounts, which are closely related to the inquiries into nature of pre-Socratic philosophy than in his historical narrative. This thesis argues that this difference is related to Herodotus’ conscious distinction between the types of questions and forms of argumentation he and his audience consider appropriate to different styles of inquiry into the causes of natural phenomena and human events. For this reason explanations involving appeal to the supernatural, while widely invoked in the narrative, are excluded from his accounts of the nature of things in the ethnographic sections of the Histories . Herodotus’ methodological self-awareness is part of his attempt to define the nature of his inquiries against other types of records of the past, which are in his view less methodologically self-conscious and, consequently, less discriminate about the evidence they rely on.