Positivism in historiography means an emphasis on facts over theory, documentary evidence over deductions from premises. It may also be called "nitty-gritticism," George Akita suggests in "Evaluating Evidence," a book that recounts the author's dealing with primary sources and the problems he has come across in appraising them. His methodical account ends with criticism of two specific works that favored conjecture over discoverable facts and, accordingly, failed.
Akita is in a position to argue for positivism. He was trained to study documents as a student, first at the University of Hawai'i, then at Harvard. The first fruit was "Foundations of Constitutional Government in Modern Japan: 1868-1900" (Harvard, 1967). It closely examined the writings of those involved in creating the Meiji government to debunk the prevailing notion that the framers of the Constitution and the advocates of political parties found each other's ideas unacceptable.
Then, when he was in his early 50s, a Japanese historian friend asked him: "What do you intend to do for your second act?" The challenger was Takashi Ito, whose strict empiricism has riven his reputation — even abroad. For example, Xinhuanet.com (of China) lists Ito among Japan's "rightwing revisionists," while Newtaiwan.com describes him as "an authority on modern Japanese history," admiringly noting that his "way of thinking is precise, his attitude toward life stern." Such a schism between Marxist scholars and those who are not has been a standard feature of modern history writing in Japan.