"compatible" with voluntary choice. Soft theological determinism is known as theological compatibilism (see figure, top right). A rejection of theological determinism (or divine foreknowledge) is classified as theological incompatibilism also (see figure, bottom), and is relevant to a more general discussion of free will. The basic argument for theological fatalism in the case of weak theological determinism is as follows: Assume divine foreknowledge or omniscience Infallible foreknowledge implies destiny (it is known for certain what one will do) Destiny eliminates alternate possibility (one cannot do otherwise) Assert incompatibility with metaphysical libertarian free will This argument is very often accepted as a basis for theological incompatibilism: denying either libertarian free will or divine foreknowledge (omniscience) and therefore theological determinism. On the other hand, theological compatibilism must attempt to find problems with it. The formal version of the argument rests on a number of premises, many of which have received some degree of contention. Theological compatibilist responses have included: Deny the truth value of future contingents, although this denies foreknowledge and therefore theological determinism. Assert differences in non-temporal knowledge (space-time independence), an approach taken for example by Boethius, Thomas Aquinas, and C.S. Lewis. Deny the Principle of Alternate Possibilities: "If you cannot do otherwise when you do an act, you do not act freely." For example, a human observer could in principle have a machine that could detect what will happen in the future, but the existence of this machine or their use of it has no influence on the outcomes of events. In the definition of compatibilism and incompatibilism, the literature often fails to distinguish between physical determinism and higher level forms of determinism (predeterminism, theological determinism, etc.) As such, hard determinism with respect to theological determinism (or "Hard Theological Determinism" above) might be classified as hard incompatibilism with respect to physical determinism (if no claim was made regarding the internal causality or determinism of the universe), or even compatibilism (if freedom from the constraint of determinism was not considered necessary for free will), if not hard determinism itself. By the same principle, metaphysical libertarianism (a form of incompatibilism with respect to physical determinism) might be classified as compatibilism with respect to theological determinism (if it was assumed such free will events were pre-ordained and therefore were destined to occur, but of which whose outcomes were not "predestined" or determined by God). If hard theological determinism is accepted (if it was