The absence of good (Latin: privatio boni), also known as the privation theory of evil, is a theological and philosophical doctrine that evil, unlike good, is insubstantial, so that thinking of it as an entity is misleading. Instead, evil is rather the absence, or lack ("privation"), of good. This also means that everything that exists is good, insofar as it exists; and is also sometimes stated as that evil ought to be regarded as nothing, or as something non-existent. Evil, on this view, is parasitic upon the good whose absence or corruption it presupposes.
The theory is most closely associated with late antique and medieval Christian thought, especially Augustine of Hippo, who adapted Neoplatonic ideas (notably from Plotinus) and argued that evil is a privation of the goodness that God has created in all things. It was further developed by figures such as Boethius, Pseudo-Dionysius, John of Damascus, and Thomas Aquinas, and later taken up—often in modified forms—by early modern philosophers like Spinoza and Leibniz.
