Duns Scotus in the context of "Avicennism"

Christian apologetics (Ancient Greek: ἀπολογία, "verbal defense, speech in defense") is a branch of Christian theology that defends Christianity.

Christian apologetics have taken many forms over the centuries, starting with Paul the Apostle in the early church and Patristic writers such as Origen, Augustine of Hippo, Justin Martyr and Tertullian, then continuing with writers such as Thomas Aquinas, Duns Scotus, William of Ockham and Anselm of Canterbury during Scholasticism.

Epistemic modal logic is a subfield of modal logic that is concerned with reasoning about knowledge. While epistemology has a long philosophical tradition dating back to Ancient Greece, epistemic logic is a much more recent development with applications in many fields, including philosophy, theoretical computer science, artificial intelligence, economics, and linguistics. While philosophers since Aristotle have discussed modal logic, and Medieval philosophers such as Avicenna, Ockham, and Duns Scotus developed many of their observations, it was C. I. Lewis who created the first symbolic and systematic approach to the topic, in 1912. It continued to mature as a field, reaching its modern form in 1963 with the work of Saul Kripke.

The Isagoge (Greek: Εἰσαγωγή, Eisagōgḗ; /ˈaɪsəɡoʊdʒiː/) or "Introduction" to Aristotle's "Categories", written by Porphyry in Greek and translated into Latin by Boethius, was the standard textbook on logic for at least a millennium after his death. It was composed by Porphyry in Sicily during the years 268–270, and sent to Chrysaorium, according to all the ancient commentators Ammonius, Elias, and David. The work includes the highly influential hierarchical classification of genera and species from substance in general down to individuals, known as the Tree of Porphyry, and an introduction which mentions the problem of universals.

Boethius' translation of the work, in Latin, became a standard medieval textbook in European scholastic universities, setting the stage for medieval philosophical-theological developments of logic and the problem of universals. Many writers, such as Boethius himself, Averroes, Peter Abelard, Duns Scotus, wrote commentaries on the book. Other writers such as William of Ockham incorporated them into their textbooks on logic.

Divine command theory (also known as theological voluntarism) is a meta-ethical theory which proposes that an action's status as morally good is equivalent to whether it is commanded by God. The theory asserts that what is moral is determined by God's commands and that for a person to be moral he is to follow God's commands. Followers of both monotheistic and polytheistic religions in ancient and modern times have often accepted the importance of God's commands in establishing morality.

Numerous variants of the theory have been presented: historically, figures including Saint Augustine, Duns Scotus, William of Ockham and Søren Kierkegaard have presented various versions of divine command theory; more recently, Robert Merrihew Adams has proposed a "modified divine command theory" based on the omnibenevolence of God in which morality is linked to human conceptions of right and wrong. Paul Copan has argued in favour of the theory from a Christian viewpoint, and Linda Trinkaus Zagzebski's divine motivation theory proposes that God's motivations, rather than commands, are the source of morality.

The Proof of the Truthful (Arabic: برهان الصديقين, romanized: burhān al-ṣiddīqīn, also translated Demonstration of the Truthful or Proof of the Veracious, among others) is a formal argument for proving the existence of God introduced by the Islamic philosopher Avicenna (also known as Ibn Sina, 980–1037). Avicenna argued that there must be a "necessary existent" (Arabic: واجب الوجود, romanized: wājib al-wujūd), an entity that cannot not exist. The argument says that the entire set of contingent things must have a cause that is not contingent because otherwise it would be included in the set. Furthermore, through a series of arguments, he derived that the necessary existent must have attributes that he identified with God in Islam, including unity, simplicity, immateriality, intellect, power, generosity, and goodness.

Historian of philosophy Peter Adamson called the argument one of the most influential medieval arguments for God's existence, and Avicenna's biggest contribution to the history of philosophy. It was enthusiastically received and repeated (sometimes with modification) by later philosophers, including generations of Muslim philosophers, Western Christian philosophers such as Thomas Aquinas and Duns Scotus, and Jewish philosophers such as Maimonides.

Mereology (/mɪəriˈɒlədʒi/; from Greek μέρος 'part' (root: μερε-, mere-) and the suffix -logy, 'study, discussion, science') is the philosophical study of part-whole relationships, also called parthood relationships. As a branch of metaphysics, mereology examines the connections between parts and their wholes, exploring how components interact within a system. This theory has roots in ancient philosophy, with significant contributions from Plato, Aristotle, and later, medieval and Renaissance thinkers like Thomas Aquinas and John Duns Scotus. Mereology was formally axiomatized in the 20th century by Polish logician Stanisław Leśniewski, who introduced it as part of a comprehensive framework for logic and mathematics, and coined the word "mereology".

Mereological ideas were influential in early § Set theory, and formal mereology has continued to be used by a minority in works on the § Foundations of mathematics. Different axiomatizations of mereology have been applied in § Metaphysics, used in § Linguistic semantics to analyze "mass terms", used in the cognitive sciences, and developed in § General systems theory. Mereology has been combined with topology, for more on which see the article on mereotopology. Mereology is also used in the foundation of Whitehead's point-free geometry, on which see Tarski 1956 and Gerla 1995. Mereology is used in discussions of entities as varied as musical groups, geographical regions, and abstract concepts, demonstrating its applicability to a wide range of philosophical and scientific discourses.

In scholastic metaphysics, a formal distinction is a distinction intermediate between what is merely conceptual, and what is fully real or mind-independent—a logical distinction. It was made by some realist philosophers of the Scholastic period in the thirteenth century, and particularly by Duns Scotus.

Haecceity (/hɛkˈsiːɪti, hiːk-/; from the Latin haecceitas, 'thisness') is a term from medieval scholastic philosophy, first coined by followers of Duns Scotus to denote a concept that he seems to have originated: the irreducible determination of a thing that makes it this particular thing. Haecceity is a person's or object's thisness, the individualising difference between the concept "a person" and the concept "Socrates" (i.e., a specific person). In modern philosophy of physics, it is sometimes referred to as primitive thisness.