Voltaire and Jean-Jacque Rousseau
Voltaire believed that education and reason could rocket humanity to new heights. His contemporary Rousseau believed the opposite: he thought "civilizing" institutions had brought out the worst in humanity, and advocated returning to a "natural" hunter-gatherer state. A witty party animal versus a Luddite naturalist? You better believe sparks flew. Voltaire even wrote to Rousseau about his work, saying,"Never was such a cleverness used in the design of making us all stupid." Ouch, JJ! Need some ointment for that burn?