Porphyry (philosopher)Porphyry of Tyre (ˈpɔrfɪri; Πορφύριος, Porphýrios; فُرْفُورِيُوس, Furfūriyūs; 234 – 305 AD) was a Neoplatonic philosopher born in Tyre, Roman Phoenicia during Roman rule. He edited and published The Enneads, the only collection of the work of Plotinus, his teacher. He wrote original works in the Greek language on a wide variety of topics, ranging from music theory to Homer to vegetarianism. His Isagoge or Introduction, an introduction to logic and philosophy, was the standard textbook on logic throughout the Middle Ages in its Latin and Arabic translations.
Abstract and concreteIn metaphysics, the distinction between abstract and concrete refers to a divide between two types of entities. Many philosophers hold that this difference has fundamental metaphysical significance. Examples of concrete objects include plants, human beings and planets while things like numbers, sets and propositions are abstract objects. There is no general consensus as to what the characteristic marks of concreteness and abstractness are.
PhaedoPhædo or Phaedo (ˈfiːdəʊ; Φαίδων, Phaidōn phaídɔːn), also known to ancient readers as On The Soul, is one of the best-known dialogues of Plato's middle period, along with the Republic and the Symposium. The philosophical subject of the dialogue is the immortality of the soul. It is set in the last hours prior to the death of Socrates, and is Plato's fourth and last dialogue to detail the philosopher's final days, following Euthyphro, Apology, and Crito. One of the main themes in the Phaedo is the idea that the soul is immortal.
Theaetetus (dialogue)The Theaetetus (ˌθiːɪˈtiːtəs; Θεαίτητος) is a philosophical work written by Plato in the early-middle 4th century BCE that investigates the nature of knowledge, and is considered one of the founding works of epistemology. Like many of Plato's works, the Theaetetus is written in the form of a dialogue, in this case between Socrates and the young mathematician Theaetetus. In the dialogue, Socrates and Theaetetus attempt to come up with a definition of episteme, or knowledge, and discuss three definitions of knowledge: knowledge as nothing but perception, knowledge as true judgment, and, finally, knowledge as a true judgment with an account.
NominalismIn metaphysics, nominalism is the view that universals and abstract objects do not actually exist other than being merely names or labels. There are at least two main versions of nominalism. One version denies the existence of universals - things that can be instantiated or exemplified by many particular things (e.g., strength, humanity). The other version specifically denies the existence of abstract objects - objects that do not exist in space and time.
Philosophical logicUnderstood in a narrow sense, philosophical logic is the area of logic that studies the application of logical methods to philosophical problems, often in the form of extended logical systems like modal logic. Some theorists conceive philosophical logic in a wider sense as the study of the scope and nature of logic in general. In this sense, philosophical logic can be seen as identical to the philosophy of logic, which includes additional topics like how to define logic or a discussion of the fundamental concepts of logic.
Clement of AlexandriaTitus Flavius Clemens, also known as Clement of Alexandria (Κλήμης ὁ Ἀλεξανδρεύς; 150 – 215 AD), was a Christian theologian and philosopher who taught at the Catechetical School of Alexandria. Among his pupils were Origen and Alexander of Jerusalem. A convert to Christianity, he was an educated man who was familiar with classical Greek philosophy and literature. As his three major works demonstrate, Clement was influenced by Hellenistic philosophy to a greater extent than any other Christian thinker of his time, and in particular, by Plato and the Stoics.
CelsusCelsus (ˈsɛlsəs; Κέλσος, Kélsos; ) was a 2nd-century Greek philosopher and opponent of early Christianity. His literary work, The True Word (also Account, Doctrine or Discourse; Greek: Λόγος Ἀληθής), survives exclusively in quotations from it in Contra Celsum, a refutation written in 248 by Origen of Alexandria. The True Word is the earliest known comprehensive criticism of Christianity. Hanegraaff has argued that it was written shortly after the death of Justin Martyr (who was possibly the first Christian apologist), and was probably a response to his work.
Process philosophyProcess philosophy, also ontology of becoming, or processism, is an approach in philosophy that identifies processes, changes, or shifting relationships as the only real experience of everyday living. In opposition to the classical view of change as illusory (as argued by Parmenides) or accidental (as argued by Aristotle), process philosophy posits transient occasions of change or becoming as the only fundamental things of the ordinary everyday real world.
EnneadsThe Enneads (Ἐννεάδες), fully The Six Enneads, is the collection of writings of the philosopher Plotinus, edited and compiled by his student Porphyry (AD 270). Plotinus was a student of Ammonius Saccas, and together they were founders of Neoplatonism. His work, through Augustine of Hippo, the Cappadocian Fathers, Pseudo-Dionysius the Areopagite and several subsequent Christian and Muslim thinkers, has greatly influenced Western and Near-Eastern thought.
