The purpose of this dissertation is to defend Pierre Fermat and Gottfried Wilhelm Leibniz against the charge of error made against them by Pierre Maupertuis that they errantly applied final causes to physics. This charge came in Maupertuis’ 1744 speech to the Paris Academy of Sciences, later published in different versions, entitled Accord Between Different Laws Which at First Seemed Incompatible. It is in this speech that Maupertuis lays claim to one of the most important discoveries in the history of (...) physics and science, The Principle of Least Action. From the date of this speech up until the end of the twentieth century, Maupertuis was credited with this discovery. Fermat discovered least time in optical physics, and Leibniz co-discovered infinitesimal calculus. When the credited discoverer of least action in physics accuses the discoverer of least time in optics and the co-discoverer of infinitesimal calculus of error before and audience of mathematicians, physicists and scientists, it is an event that calls out for investigation. The idea of final causes in physics is the idea that bodies move for an end purpose. During the early modern period, this challenged the intellectual establishment of the day with the idea of thinking in nature. The question which fueled the research for this dissertation is why such a man would accuse two other prominent intellects with such an unprovable metaphysical assumption. The research for this project started with a study of the positions of all three of these men regarding final causes in physics. The second phase was to research the historical context in which Accord Between Different Laws Which at First Seemed Incompatible was written and delivered. This context included the life of Maupertuis as member of the Paris Academy of Sciences and as later President of the Berlin Academy of Sciences. It also included the workings of three highly competitive, state funded, academies of science in Berlin, London and Paris. Research showed that no formal positions were held on the subject of final causes by either Maupertuis or Fermat. Only Leibniz demonstrated an established and well thought out position on the subject. Research did reveal the story of an ambitious man in Maupertuis, who made it the fulfillment of his ambition to rise in the ranks of math and science within the academies and establish himself as an intellectual great in European culture. Consequently, the life and career of Maupertuis illustrates the sociological dimension of scientific achievement. Accord Between Different Laws Which at First Seemed Incompatible turned out to be a politically calculated speech delivered for the purpose of career advancement. In 1744, Maupertuis was being considered by the King of Prussia, Frederick the Great, and the leadership of the Berlin Academy of Science for the presidency of that institution. Maupertuis knew this. Therefore, the work must be interpreted in this context. Consequently, the charge of error against Fermat and Leibniz by Maupertuis must be interpreted likewise. Discovery was made in contextual and Leibnizian research that Maupertuis was aware of Leibniz’s idea of action from 1738 on, and knowingly claimed to have discovered a generalized notion of action in physics which was not his. It is the story of ambition clouding human judgment. The Leibnizians attacked Maupertuis on this matter, led by a member of the Berlin Academy named Samuel Konig. In the “Konig Affair”, Konig accused Maupertuis of what is essentially plagiarism, and Maupertuis countered with charging Konig with forgery for claiming to have in his possession a letter from Leibniz to Jacob Hermann demonstrating Leibniz’s knowledge of least action. Maupertuis buries Konig in legal proceedings, but loses his reputation in the process. During the final stages of the Konig affair, Maupertuis admits to Patrick d’Arcy, a member of the Paris academy, that he had used Leibniz’s theory of action. Having lost his effective leadership as President of the Berlin Academy, Maupertuis spends the last years of his life in his native France without ever relinquishing his title and office. When at first examining the charge of error, the immediate notion is that this is a cause and effect argument. It appears to be an argument about the order of metaphysics before physics. This turns out not to be the case. Maupertuis agrees with Fermat and Leibniz at every turn. The charge is all about career success. (shrink)