Kantianism
Kantianism is the philosophy of Immanuel Kant, a German philosopher born in Königsberg, Prussia (now Kaliningrad, Russia). The term "Kantianism" or "Kantian" is sometimes also used to describe contemporary positions in philosophy of mind, epistemology, and ethics.
Ontological argument
Although a version of the ontological argument appears explicitly in the writings of the ancient Greek philosopher Xenophanes and variations appear in writings by Parmenides, Plato, and the Neoplatonists, the mainstream view is that the ontological argument was first clearly stated and developed by Anselm of Canterbury. Some scholars argued that the Islamic philosopher Avicenna (Ibn Sina) developed a special kind of ontological argument before Anselm, but other scholars have doubted this position. Daniel Dombrowski marked three major stages in the development of the argument: Anselm's initial explicit formulation; the eighteenth-century criticisms of Kant and Hume; and the identification of a second ontological argument in Anselm's "Proslogion" by twentieth-century philosophers.