The democratic peace theory is now one of the great controversies in political science and one of the main challenges to realism in international relations. More than a hundred different researchers have published multiple articles in this field, according to an incomplete bibliography. Some critics argue that there have been exceptions to the democratic peace. Rummel discussed some claimed exceptions in his FAQ and he has referred to books by other scholars such as "Never at War". Criticism of the democratic peace theory include data, definition, historical periods, limited consequences, methodology, microfoundations, and statistical significance criticism, that peace comes before democracy and that several studies fail to confirm democracies are less likely to wage war than autocracies if wars against non-democracies are included. Jeffrey Pugh summarized those who dispute the theory often do so on grounds that it conflates correlation with causation and that the academic definitions of "democracy" and "war" can be manipulated so as to manufacture an artificial trend. Rummel's first work on democratic peace received little attention. His results were incorporated in a "gigantic philosophical scheme" of 33 propositions in a 5-volume work. It was reviewed in 1992 as having "immoderate pretensions", and demonstrated Rummel's "unrelenting" economic liberalism and "extreme" views on defense policy. Nils Petter thought these elements may have distracted readers from Rummel's more conventionally acceptable propositions.