The oldest question of metaphysics, from Parmenides' changeless One to Heidegger's forgotten question of Being and Quine's terse 'to be is to be the value of a variable'.
Why is there something rather than nothing — and what does it mean for anything at all to be?
Being is the concept metaphysics cannot do without and can never quite pin down: to ask what it means for anything to exist is to ask the most general question there is. Parmenides made Being one, changeless and full, banishing not-being; Aristotle answered that being is 'said in many ways' and made substance its focus. Medieval thinkers debated whether existence is distinct from essence and whether 'being' means the same when applied to God and creatures. Modern philosophy split between grand systems of Being-as-such and the sober project of asking merely what there is. Heidegger charged the whole tradition with forgetting the question of Being itself, while analytic philosophers reduced it to the logic of quantification. Set side by side, these positions show how one small word carries the weight of an entire discipline.
Pre-Socratic (Eleatic)
'What is, is; what is not, is not.' Being is one, ungenerated, indivisible, changeless and complete, for coming-to-be would require it to arise from not-being, which cannot even be thought or spoken. Change and plurality are illusions of the senses; only the path of Being can be truly known.
On Nature (poem, surviving in fragments).
Pre-Socratic
Against a static Being, Heraclitus makes flux fundamental: 'everything flows', and one cannot step twice into the same river. Yet the ceaseless change is governed by the logos, a hidden measure and unity of opposites, so that reality's being lies precisely in its becoming.
On Nature (fragments): 'panta rhei' — everything flows.
Ancient Greek (Platonism)
True being belongs to the eternal, unchanging Forms, which are fully real; sensible things merely 'participate' in them and hover between being and not-being. In the Sophist Plato even rehabilitates a kind of not-being as difference, allowing us to speak meaningfully of what is not.
Republic; Sophist; Timaeus.
Ancient Greek (Peripatetic)
'Being is said in many ways': it is not a single genus but analogically related senses, with substance (ousia) as primary and qualities, quantities and relations dependent on it. First philosophy studies 'being qua being', and Aristotle analyses it through potency and act, form and matter.
Metaphysics, especially Books IV, VII and IX.
Neoplatonism
Being is not ultimate: it flows from the One, which is 'beyond being' and utterly simple. From the One emanates Intellect (the realm of true being and the Forms), then Soul, then the sensible world; each level is a diminished image of what precedes, and all things yearn to return to their source.
The Enneads.
Islamic Aristotelianism
Avicenna draws a lasting distinction between essence and existence: in every creature existence is 'added' to essence, so contingent things merely possibly exist and require a cause. Only the Necessary Being (God) exists through itself, its essence being identical with its existence; from it all else necessarily flows.
The Book of Healing (Kitāb al-Shifāʾ); The Book of Salvation.
Scholasticism
Aquinas makes the act of existing (esse) the deepest actuality of every being; in creatures essence and existence are really distinct, but in God alone essence is existence — God is ipsum esse subsistens, subsistent Being itself. Everything else has being by participation in and dependence upon this first cause.
On Being and Essence; Summa Theologiae, I, q. 3–4.
Scholasticism (Franciscan)
Against the analogy of being, Scotus argues that 'being' is univocal — it has one single meaning applicable to God and creatures alike, differing in mode (infinite vs. finite) rather than sense. Only a univocal concept of being, he holds, makes natural knowledge of God possible at all.
Ordinatio (Opus Oxoniense).
Rationalism
There is only one substance, God or Nature (Deus sive Natura), which exists necessarily and of which all finite things are modes. Being is a single, self-caused infinite reality expressing itself through infinite attributes; particular beings are not independent substances but transient modifications of the one.
Ethics (1677), Part I, 'Concerning God'.
German idealism
Hegel begins his Logic with pure Being — the emptiest, most indeterminate concept, which for that very reason passes over into Nothing; their truth is Becoming. Being is thus not a static ground but the first, abstract moment of a dialectical process in which the fullness of reality unfolds through its own contradictions.
Science of Logic (1812–16), 'The Doctrine of Being'.
Madhyamaka Buddhism
Nāgārjuna denies that anything possesses svabhāva — inherent, independent being. All things are 'empty', existing only dependently, in relation to conditions and to one another. This is not nihilism: the middle way rejects both substantial being and sheer non-being, dissolving the very dichotomy that other ontologies presuppose.
Mūlamadhyamakakārikā (Fundamental Verses on the Middle Way).
Phenomenology / existential ontology
Western philosophy, Heidegger charges, has forgotten the question of Being itself, confusing Being with particular beings. He reopens it by analysing the one entity for whom Being is a question — Dasein, human existence — whose temporal, finite, world-involved way of being is the clue to the meaning of Being as such.
Being and Time (1927).
Existentialism
Sartre divides reality into being-in-itself (the solid, self-identical being of things) and being-for-itself (consciousness, which is a 'nothingness' that must perpetually make itself). Human being has no fixed essence; because existence precedes essence, we are the beings through whom nothingness enters the world.
Being and Nothingness (1943).
Analytic philosophy
Quine deflates the grand question of Being into a logical one: 'to be is to be the value of a bound variable.' A theory's ontological commitments are just the entities its true statements must quantify over. What there is becomes a matter of which regimented theory best fits experience, weighed by simplicity and explanatory power.
'On What There Is' (1948); Word and Object (1960).