Ploucquet, Gottfried a German philosopher, was born Aug. 25, 1716, at Stuttgard. He came from a Protestant family of French origin; his father was an innkeeper. While he was studying at Tübingen, he was so strongly impressed by Wolf's writings that, without giving up theology altogether, he gave special attention to the study of philosophy and mathematics. This twofold tendency strikingly appears in the theses which he defended in 1740 (Diss. qua Cl. Varignonii demonstratio geometrica possibilitatis transubstantionis enervatur), and in which he endeavored to reconcile Wolf's doctrines with the teachings of the Christian faith. After discharging in different places the duties of a minister and tutor, he was appointed in 1746 deacon at Freudenstadt. His memoir on the monads (Primaria Monadologic capita [Berlin, 1748, 4to]) opened to him in 1749 the Academy of Sciences of Berlin and directed to him the attention of the duke of Würtemberg, by whose protection he obtained, in 1750, the professorship of logic and metaphysics at Tübingen. He taught political economy at the same university, and was, in 1778, called to Stuttgard to teach this branch at the military school. His faculties having given way in consequence of a stroke of apoplexy, in 1782 he was compelled to abandon teaching. Ploucquet was an honest and open character, and he was gifted by nature with a clear and methodical mind. '"A champion of spiritualism," says Mr. Haag, "he combated, with a degree of penetration equaled only by his erudition, the materialistic doctrines proclaimed by the philosophers of the 18th century, and feared not even to enter into contest with Kant. Then, ascending the stream of the centuries, he submitted to strict analysis the systems of ancient philosophy, which he tried to build anew in historical essays, worthy even now of our attention." Ploucquet died at Stuttgard Sept. 13, 1790. He left a number of works, mostly published at Tübingen, and written with great purity, but rather exaggerated concision. The following are the most important: De miaterialismo (1750, 4to): — Principia de substantiis et phenomenis (Frankfort, 1758, 8vo): — De Pyrrholni epocha (1758, 4to): — Fundlamenta philosophite speculativce (7th ed. 1759, 8vo); it is an exposition of Leibnitz's system: — De dogmatibus Thaletis et Anaxagorae (1763, 4to): — Methodus calculandi in logicis (1763, 8vo). In this work he represents the syllogisms by geometrical figures and mathematical formulas; these methods, hinted at by Leibnitz, engaged him in discussions with Lambert and others: — Problemata de natura hominis ante et post
mortern (1766, 4to): — Institutiones philosophice theoreticma (1772, 1782, 8vo): — Elementa philosophiae contemplativae, sive de scientia ratiocinandi (Stuttgard, 1773, 4to): — Commentationes philosophiae selectiores (Utrecht, 1781, 4to): — Varice questiones metatphysic (1782, 4to). — Hoefer, Nouv. Biog. Géneralé, 40, 494.