LogicLogic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or logical truths. It studies how conclusions follow from premises due to the structure of arguments alone, independent of their topic and content. Informal logic is associated with informal fallacies, critical thinking, and argumentation theory. It examines arguments expressed in natural language while formal logic uses formal language.
ChrysippusChrysippus of Soli (kraɪˈsɪpəs,_krɪ-; Χρύσιππος ὁ Σολεύς, Chrysippos ho Soleus; 279 – 206 BC) was a Greco-Phoenician Stoic philosopher. He was a native of Soli, Cilicia, but moved to Athens as a young man, where he became a pupil of the Stoic philosopher Cleanthes. When Cleanthes died, around 230 BC, Chrysippus became the third head of the Stoic school. A prolific writer, Chrysippus expanded the fundamental doctrines of Cleanthes' mentor Zeno of Citium, the founder and first head of the school, which earned him the title of the Second Founder of Stoicism.
Disjunctive syllogismIn classical logic, disjunctive syllogism (historically known as modus tollendo ponens (MTP), Latin for "mode that affirms by denying") is a valid argument form which is a syllogism having a disjunctive statement for one of its premises. An example in English: The breach is a safety violation, or it is not subject to fines. The breach is not a safety violation. Therefore, it is not subject to fines. In propositional logic, disjunctive syllogism (also known as disjunction elimination and or elimination, or abbreviated ∨E), is a valid rule of inference.
EpictetusEpictetus (ˌɛpɪkˈtiːtəs, ; Ἐπίκτητος, Epíktētos; 50 135 AD) was a Greek Stoic philosopher. He was born into slavery at Hierapolis, Phrygia (present-day Pamukkale, in western Turkey) and lived in Rome until his banishment, when he went to Nicopolis in northwestern Greece for the rest of his life. His teachings were written down and published by his pupil Arrian in his Discourses and Enchiridion. Epictetus taught that philosophy is a way of life and not simply a theoretical discipline.
StoicismStoicism is one of the four major schools of thought established in the Hellenistic period. It was founded in the ancient Agora of Athens by Zeno of Citium around 300 BC. The Stoics believed that the practice of virtue is enough to achieve eudaimonia: a well-lived, flourishing life. The Stoics identified the path to achieving it with a life spent practicing certain virtues in everyday life such as courage or temperance and living in accordance with nature.
Hypothetical syllogismIn classical logic, a hypothetical syllogism is a valid argument form, a syllogism with a conditional statement for one or both of its premises. An example in English: If I do not wake up, then I cannot go to work. If I cannot go to work, then I will not get paid. Therefore, if I do not wake up, then I will not get paid. The term originated with Theophrastus. A pure hypothetical syllogism is a syllogism in which both premises and conclusions are conditionals.
NeoplatonismNeoplatonism is a version of Platonic philosophy that emerged in the 3rd century AD against the background of Hellenistic philosophy and religion. The term does not encapsulate a set of ideas as much as a series of thinkers. Among the common ideas it maintains is monism, the doctrine that all of reality can be derived from a single principle, "the One". Neoplatonism began with Ammonius Saccas and his student Plotinus (c. 204/5–271 AD) and stretched to the 6th century AD.
Modus tollensIn propositional logic, modus tollens (ˈmoʊdəs_ˈtɒlɛnz) (MT), also known as modus tollendo tollens (Latin for "method of removing by taking away") and denying the consequent, is a deductive argument form and a rule of inference. Modus tollens takes the form of "If P, then Q. Not Q. Therefore, not P." It is an application of the general truth that if a statement is true, then so is its contrapositive. The form shows that inference from P implies Q to the negation of Q implies the negation of P is a valid argument.
Hellenistic philosophyHellenistic philosophy is Ancient Greek philosophy corresponding to the Hellenistic period in Ancient Greece, from the death of Alexander the Great in 323 BC to the Battle of Actium in 31 BC. The dominant schools of this period were the Stoics, the Epicureans and the Skeptics. The preceding classical period in Ancient Greek philosophy had centered around Socrates (c. 470–399 BC), whose students Antisthenes, Aristippus, and Plato went on to found Cynicism, Cyrenaicism, and Platonism, respectively.
