In this dissertation I identify the philosophy of Giambattista Vico and Karl Marx as representing, broadly, two rival versions of historical inquiry. Put simply, these rival versions endorse either reasons or causes, respectively, as the proper objects of study for historians. After introducing the study of the ratification of the Sixteenth Amendment to the U.S. Constitution as an example of the type of historical event towards which these versions of inquiry might by directed, I then outline the arguments Vico and Marx give for these rival versions. Paying special attention to the assumptions about human nature, reason, and freedom at work in these arguments, I propose that comparing the plausibility and feasibility of these assumptions might allow a means of adjudicating between these comprehensive and mutually incompatible methods of historical study. I proceed to draw on the work of John Rawls and Alasdair MacIntyre, among others, to show that MarxÂs conceptions of human nature, reason, and freedom are ultimately flawed and therefore untenable. I conclude by arguing that VicoÂs version of historical inquiry relies on an understanding of these concepts that is more plausible than MarxÂs and withstands the objections to which MarxÂs understanding succumbs. Finally, I return my focus to the study of the Sixteenth Amendment and consider how VicoÂs version of historical inquiry might inform this project
