Example image of eyePlorer eyePlorer map for 'Existence': Essence Abstraction Category Idea Latin Predicate (mathematical logic) Etymology Aristotle Avicenna Hume Immanuel Kant Parmenides Plato Scotus Søren Kierkegaard Thomas Aquinas Nagarjuna Being Category of being Existence Ontology Philosophy Reality Entity Hierarchy Metaphysics Criteria of truth Cosmogony Propositional calculus First-order logic Domain of discourse Quantification Existential quantification Mathematical logic Well-formed formula Universal quantification Validity Logical connective Truth table Empirical Evidence Inquiry Measure Observable Reasoning Demarcation problem Philosophy of science Research ethics Scientific method Naturalism (philosophy)