William of Ockham

"Intuitive cognition is such that when some things are cognized, of which one inheres in the other, or one is spatially distant from the other, or exists in some relation to the other, immediately in virtue of that non-propositional cognition of those things, it is known if the thing inheres or does not inhere, if it is spatially distant or not, and the same for other true contingent propositions, unless that cognition is flawed or there is some impediment."

"The head of Christians does not, as a rule, have power to punish secular wrongs with a capital penalty and other bodily penalties and it is for thus punishing such wrongs that temporal power and riches are chiefly necessary; such punishment is granted chiefly to the secular power. The pope therefore, can, as a rule, correct wrongdoers only with a spiritual penalty. It is not, therefore, necessary that he should excel in temporal power or abound in temporal riches, but it is enough that Christians should willingly obey him."

"Historically, Ockham has been cast as the outstanding opponent of Thomas Aquinas (1224–1274): Aquinas perfected the great "medieval synthesis" of faith and reason and was canonized by the Catholic Church; Ockham destroyed the synthesis and was condemned by the Catholic Church. Although it is true that Aquinas and Ockham disagreed on most issues, Aquinas had many other critics, and Ockham did not criticize Aquinas any more than he did others. It is fair enough, however, to say that Ockham was a major force of change at the end of the Middle Ages. He was a courageous man with an uncommonly sharp mind. His philosophy was radical in his day and continues to provide insight into current philosophical debates. The principle of simplicity is the central theme of Ockhams approach, so much so that this principle has come to be known as "Ockhams Razor." Ockham uses the razor to eliminate unnecessary hypotheses. In metaphysics, Ockham champions nominalism, the view that universal essences, such as humanity or whiteness, are nothing more than concepts in the mind. He develops an Aristotelian ontology, admitting only individual substances and qualities. In epistemology, Ockham defends direct realist empiricism, according to which human beings perceive objects through "intuitive cognition," without the help of any innate ideas. These perceptions give rise to all of our abstract concepts and provide knowledge of the world. In logic, Ockham presents a version of supposition theory to support his commitment to mental language. Supposition theory had various purposes in medieval logic, one of which was to explain how words bear meaning. Theologically, Ockham is a fideist, maintaining that belief in God is a matter of faith rather than knowledge. Against the mainstream, he insists that theology is not a science and rejects all the alleged proofs of the existence of God."

"Numquam ponenda est pluralitas sine necessitate"

"It is on account of theology alone that any assertion whatsoever should be called catholic or heretical. For only an assertion which is consonant with theology is truly catholic, and only one which is known to be opposed to theology is known to be heretical. For if some assertion were found to be opposed to decrees of the highest pontiffs, or also of general councils or also to laws of the emperors, nevertheless, if it were not in conflict with theology, even if it could be considered false, erroneous or unjust, it should not be counted as a heresy."

"Logic is the most useful tool of all the arts. Without it no science can be fully known. It is not worn out by repeated use, after the manner of material tools, but rather admits of continual growth through the diligent exercise of any other science. For just as a mechanic who lacks a complete knowledge of his tool gains a fuller [knowledge] by using it, so one who is educated in the firm principles of logic, while he painstakingly devotes his labor to the other sciences, acquires at the same time a greater skill at this art."