Epistemic Argument for Atheism
(I1) It is unreasonable to believe that an object exists unless we have (some) sufficient evidence for its existence.
(I2) Law of Causality: Every material effect must have an adequate antecedent or simultaneous cause; the nature of the effect depends, amongst other factors, on the nature of the cause.
(A) Perception, and therefore awareness, of any object is contingent upon the existence of a causal chain between the object and our senses. (corollary of I2)
Explanation: Without some effect of the object, the properties of said object would not impinge on our senses.
(B) If we cannot even in principle be aware of the existence of an object, then the rational conclusion is to conclude that it does not exist. (corollary of I1)
Explanation: For an object to be unavailable to the senses means it creates no effect in the universe. It is therefore indistinguishable from nothing.
(C) Occam’s Razor: the most parsimonious explanation is the only one that fulfills the burden of proof. (corollary of I1)
Explanation: If two hypotheses H1 and H2 explain the same set of phenomena P, but H1 is more parsimonious, then we can say that P provides evidence for at most the entities and processes involved in H1. The extraneous entities or processes involved in H2 have no further evidence on the basis of P, therefore we should not believe in them on the basis of P.
(D) Knowledge is contingent on the uniformity of nature. (corollary of I2)
Explanation: All knowledge presupposes that the causal relationships that gave rise to it will not change and have not changed. Even a trivial statement like “the sky is blue” relies on the uniformity of how our brain represents colors.
(1) God is partially defined as a non-natural being (i.e. it exists outside the universe and its laws) which may interact with the universe.
(2) Either God (a) does not actually interact with the universe, (b) only interacts with the universe in accordance with natural laws or (c) interacts with the universe and may do so in violation of natural laws.
(3) If (a), then we cannot be aware of God, and we must rationally conclude that God does not exist. (from A and B)
(4) If (b), then we cannot distinguish God’s actions from natural law, natural law is the most parsimonious explanation, and this scenario therefore collapses into 3. (from C)
(5) If (c), then we cannot hold to any knowledge, including the knowledge that God exists, and we must conclude that nothing can ever be satisfactorily demonstrated, including God’s existence. In such a situation, all beliefs are unwarranted, including belief in God. (from D)
(6) Therefore we are justified in disbelieving in God on an epistemic basis. (from 3. 4 and 5)
Intuitionist Argument for the Non-Existence of God
(I1) Harming innocents is wrong.
(I2) It is unreasonable to believe that an object exists unless we have (some) sufficient evidence for its existence.
(I3) Contradictions cannot exist.
(A) Torturing an infant is wrong. (from I1)
(¬A) Torturing an infant is not wrong.
(B) Occam’s Razor: the most parsimonious explanation is the only one that fulfills the burden of proof. (corollary of I2)
(C) If the existence of an object implies a contradiction, then that object cannot exist. (corollary of I3)
(1) God is partially defined as a being (external to oneself) upon which the validity and force of ethical beliefs are contingent.
(2) Either A is valid and forceful (a) because it is intuitively true or the result of deliberation applied to some intuition, (b) because it was decreed by some external agency which cannot also bring about ¬A, or (c) because it was decreed by some external agency which can also bring about ¬A.
(3) If (a), then the validity and force of A are not contingent on any external agent, therefore God does not exist.
(4) If (b), then we cannot distinguish between A being intuitively true and A being the result of the actions of some external agency, intuition becomes the most parsimonious explanation, and this scenario therefore collapses into 3. (from B)
(5) If (c), then A and ¬A can both be valid and forceful, which is a contradiction, therefore God cannot exist. (from C)
(6) Therefore God does not exist. (from 3, 4 and 5)