Ancient philosophy in the context of "Propositions"

Classics, also classical studies or Ancient Greek and Roman studies, is the study of classical antiquity. In the Western world, classics traditionally refers to the study of Ancient Greek and Roman literature and their original languages, Ancient Greek and Latin. Classics may also include as secondary subjects Greco-Roman philosophy, history, archaeology, anthropology, architecture, art, mythology, and society.

In Western civilization, the study of the Ancient Greek and Roman classics was considered the foundation of the humanities, and they traditionally have been the cornerstone of an elite higher education.

Dialectic (Ancient Greek: διαλεκτική, romanized: dialektikḗ; German: Dialektik), also known as the dialectical method, refers originally to dialogue between people holding different points of view about a subject but wishing to arrive at the truth through reasoned argument. Dialectic resembles debate, but the concept excludes subjective elements such as emotional appeal and rhetoric; the object is more an eventual and commonly-held truth than the 'winning' of an (often binary) competition. It has its origins in ancient philosophy and continued to be developed in the Middle Ages.

Hegelianism refigured "dialectic" to no longer refer to a literal dialogue. Instead, the term takes on the specialized meaning of development by way of overcoming internal contradictions. Dialectical materialism, a theory advanced by Karl Marx and Friedrich Engels, adapted the Hegelian dialectic into a materialist theory of history. The legacy of Hegelian and Marxian dialectics has been criticized by philosophers, such as Karl Popper and Mario Bunge, who considered it unscientific.

Heraclitus (/ˌhɛrəˈklaɪtəs/; Ancient Greek: Ἡράκλειτος Hērákleitos; fl. c. 500 BC) was an ancient Greek pre-Socratic philosopher from the city of Ephesus, which was then part of the Persian Empire. He exerts a wide influence on Western philosophy, both ancient and modern, through the works of such authors as Plato, Aristotle, Georg Wilhelm Friedrich Hegel, Friedrich Nietzsche, and Martin Heidegger.

Little is known of Heraclitus's life. He wrote a single work, of which only fragments survive. Even in ancient times, his paradoxical philosophy, appreciation for wordplay, and cryptic, oracular epigrams earned him the epithets "the dark" and "the obscure". He was considered arrogant and depressed, a misanthrope who was subject to melancholia. Consequently, he became known as "the weeping philosopher" in contrast to the ancient atomist philosopher Democritus, who was known as "the laughing philosopher".

Iranian philosophy (Persian: فلسفه ایرانی) or Persian philosophy can be traced back as far as to Old Iranian philosophical traditions and thoughts which originated in ancient Indo-Iranian roots and were considerably influenced by Zarathustra's teachings. According to the Oxford Dictionary of Philosophy, the chronology of the subject and science of philosophy starts with the Indo-Iranians, dating this event to 1500 BC. The Oxford dictionary also states, "Zarathustra's philosophy entered to influence Western tradition through Judaism, and therefore on Middle Platonism."

Throughout Iranian history and due to remarkable political and social changes such as the Arab and Mongol invasions of Persia, a wide spectrum of schools of thoughts showed a variety of views on philosophical questions extending from Old Iranian and mainly Zoroastrianism-related traditions, to schools appearing in the late pre-Islamic era such as Manicheism and Mazdakism as well as various post-Islamic schools. Iranian philosophy after the Muslim conquest of Persia, is characterized by different interactions with the Old Iranian philosophy, the Greek philosophy and with the development of Islamic philosophy. The Illumination School and the Transcendent Philosophy are regarded as two of the main philosophical traditions of that era in Persia.

Leucippus (/luːˈsɪpəs/; Λεύκιππος, Leúkippos; fl. 5th century BCE) was a pre-Socratic Greek philosopher. He is traditionally credited as the founder of atomism, which he developed with his student Democritus. Leucippus divided the world into two entities: atoms, indivisible particles that make up all things, and the void, the nothingness that exists between the atoms. He developed his philosophy as a response to the Eleatics, who believed that all things are one and the void does not exist. Leucippus's ideas were influential in ancient and Renaissance philosophy. Leucippus was the first Western philosopher to develop the concept of atoms, but his ideas only bear a superficial resemblance to modern atomic theory.

Leucippus's atoms come in infinitely many forms and exist in constant motion, creating a deterministic world in which everything is caused by the collisions of atoms. Leucippus described the beginning of the cosmos as a vortex of atoms that formed the Earth, the Sun, the stars, and other celestial bodies. As Leucippus considered both atoms and the void to be infinite, he presumed that other worlds must exist as cosmoses are formed elsewhere. Leucippus and Democritus described the soul as an arrangement of spherical atoms, which are cycled through the body through respiration and create thought and sensory input.

Propositions are the meanings of declarative sentences, objects of beliefs, and bearers of truth values. They explain how different sentences, like the English "Snow is white" and the German "Schnee ist weiß", can have identical meaning by expressing the same proposition. Similarly, they ground the fact that different people can share a belief by being directed at the same content. True propositions describe the world as it is, while false ones fail to do so. Researchers distinguish types of propositions by their informational content and mode of assertion, such as the contrasts between affirmative and negative propositions, between universal and existential propositions, and between categorical and conditional propositions.

Many theories of the nature and roles of propositions have been proposed. Realists argue that propositions form part of reality, a view rejected by anti-realists. Non-reductive realists understand propositions as a unique kind of entity, whereas reductive realists analyze them in terms of other entities. One proposal sees them as sets of possible worlds, reflecting the idea that understanding a proposition involves grasping the circumstances under which it would be true. A different suggestion focuses on the individuals and concepts to which a proposition refers, defining propositions as structured entities composed of these constituents. Other accounts characterize propositions as specific kinds of properties, relations, or states of affairs. Philosophers also debate whether propositions are abstract objects outside space and time, psychological entities dependent on mental activity, or linguistic entities grounded in language. Paradoxes challenge the different theories of propositions, such as the liar's paradox. The study of propositions has its roots in ancient philosophy, with influential contributions from Aristotle and the Stoics, and later from William of Ockham, Gottlob Frege, and Bertrand Russell.