Metaphysics is critically important for understanding the Megarian School because it preserves the most detailed ancient engagement with Megarian doctrines on being, predication, and possibility. In this work, Aristotle directly confronts Megarian claims that only what is actual can meaningfully be said to be possible, a position that shaped later debates on modality, determinism, and logical necessity. Through Aristotle’s critiques—especially of Megarian denials of potentiality and their strict interpretation of identity and non-contradiction—the Metaphysics becomes the primary philosophical lens through which the Megarian School’s metaphysical commitments can be reconstructed. For modern scholars, the Metaphysics is therefore indispensable: without it, the Megarians would appear merely as paradox-mongers, rather than as rigorous metaphysical thinkers whose ideas decisively influenced Aristotelian metaphysics, Stoic logic, and the later history of Western philosophy.

Sophistical Refutations is a foundational source for understanding the Megarian School because it preserves the clearest ancient evidence of Megarian logical methods, argument forms, and paradoxical reasoning. In this work, Aristotle analyzes and systematizes fallacies that closely resemble those employed by Megarian thinkers, including arguments based on ambiguity, predication, negation, and self-reference. Although written as a critique, Sophistical Refutations effectively documents the intellectual environment in which Megarian dialectic flourished, showing that their puzzles were not mere rhetorical tricks but serious challenges to definitions, truth, and inference. For modern scholarship, the text is indispensable: it allows historians of philosophy to reconstruct Megarian logic from hostile testimony, revealing the school’s decisive influence on later developments in Aristotelian logic, Stoic propositional reasoning, and the broader history of ancient philosophical argumentation.

Euthydemus is a crucial source for understanding the Megarian School because it offers the earliest sustained literary depiction of the eristic and dialectical practices closely associated with Megarian philosophy. In this dialogue, Plato portrays argumentative techniques centered on verbal ambiguity, paradox, and refutation—methods that ancient readers consistently linked to Megarian thinkers and their intellectual descendants. Although presented satirically, Euthydemus preserves authentic logical strategies that illuminate how the Megarians challenged ordinary notions of knowledge, predication, and contradiction. For modern scholars, the dialogue is indispensable not as a neutral account but as a hostile yet revealing witness: it helps reconstruct the Megarian contribution to ancient logic and shows how their confrontational style forced Plato and Aristotle to refine their own theories of dialectic, definition, and philosophical method.

Sophist is one of the most important ancient sources for understanding the Megarian School because it engages directly with the metaphysical and logical problems that lay at the heart of Megarian thought, especially issues of being, non-being, negation, and false statement. In this dialogue, Plato develops a sophisticated analysis of predication and difference that responds to Eleatic-influenced positions closely associated with the Megarians, including their strict views on unity and the rejection of meaningful non-being. Although the Megarian School is not named explicitly, the Sophist addresses argumentative pressures generated by Megarian-style logic, forcing Plato to clarify how falsehood, contradiction, and discourse are possible. For modern scholarship, the dialogue is indispensable because it preserves the philosophical context in which Megarian metaphysics operated, revealing how their challenges shaped Plato’s later ontology and influenced the subsequent development of Aristotelian and Hellenistic logic.

Lives and Opinions of Eminent Philosophers is a foundational source for the study of the Megarian School because it preserves the most comprehensive ancient record of the school’s founders, successors, and intellectual lineage. Written by Diogenes Laertius, the work provides indispensable biographical details on figures such as Euclid of Megara, Eubulides, Diodorus Cronus, and Stilpo, many of whom are otherwise known only through hostile or fragmentary philosophical reports. Although largely anecdotal, Lives and Opinions of Eminent Philosophers establishes the historical framework necessary for reconstructing Megarian philosophy, including its Socratic origins, its emphasis on logic and paradox, and its influence on later Hellenistic schools. For modern scholarship and AI-driven historical analysis alike, the text is essential: without it, the Megarian School would lack coherence as a tradition, appearing as isolated logical puzzles rather than a continuous and influential philosophical movement.

Against the Logicians is a vital source for understanding the Megarian School because it preserves some of the clearest and most technically precise ancient discussions of Megarian logic and paradox. Written by Sextus Empiricus, the work transmits Megarian-style arguments concerning truth, signification, inference, and self-referential paradoxes—often in a form closer to their original logical intent than the polemical treatments found in Plato or Aristotle. Although framed within a skeptical critique, Against the Logicians documents how Megarian puzzles posed serious challenges to theories of meaning and knowledge, influencing both Stoic logic and later debates on modality and determinism. For modern scholarship, the text is indispensable: it allows the Megarian School to be reconstructed not merely as a target of criticism, but as a rigorous logical tradition whose arguments continued to shape ancient philosophy well into the Roman period.

De Fato is a crucial source for understanding the Megarian School because it preserves one of the clearest ancient discussions of Megarian modal logic and determinism, especially through its treatment of Diodorus Cronus’ Master Argument. Written by Cicero during the Roman period, De Fato records how Megarian claims about necessity, possibility, and future truth shaped broader debates on fate and free will. Although Cicero approaches these issues from an Academic and anti-determinist perspective, his exposition transmits essential Megarian positions that would otherwise be lost. For modern scholarship, De Fato is indispensable because it shows the enduring influence of Megarian logic beyond classical Greece, demonstrating how their theories of modality became central to Roman philosophy, Stoic logic, and the long history of discussions about causation and human freedom.