Logical arguments for atheism attempt to show that the concept of God is self-contradictory or logically inconsistent with some known fact. In the jargon of the philosophy of religion, the former type of logical arguments are sometimes called incompatible-properties arguments. These arguments attempt to demonstrate a contradiction in the concept of God. If an argument of this type were successful, it would mean that the existence of God is impossible; there is a 0% probability that God exists.
In this paper Horia Plugaru argues that if the traditional theistic God were to exist, then there are strong reasons to think that there would exist only deities. If the argument succeeds, then God would have no rational grounds for creating our present world, which contains nondeities. But since the present world clearly exists, it follows that God does not exist. After offering a formal presentation of the argument, Plugaru defends its crucial first premise before responding to five potential objections to the argument.
In this paper Ryan Stringer discusses arguments from perfection, both for and against the existence of God. He begins with a simple argument from perfection for the existence of God and argues that it is unsuccessful. Then he defends two kinds of arguments from perfection against the existence of God. The first ones are inductive and thus present atheism as a tentative conclusion, while the second one is deductive and thus purports to conclusively demonstrate atheism based on the logical inconsistency between God's existence and the imperfect world in which we live.
Smith presents a logical argument for atheism based upon the incompatibility of "God is the originating cause of the universe" with all possible valid definitions or theories of causality.
'God' in one sense that is widely accepted in non-academic circles is self contradictory and thus that God in this sense cannot exist. Martin first gives a rather informal exposition of the disproof, followed by a more formal version. Finally, Martin defends the disproof against possible objections.
Dan Barker argues that two of the traditional divine attributes are incompatible with one another: divine freedom and divine foreknowledge.
Rachels defends an argument for the nonexistence of God based on the impossibility of a being worthy of worship.
Ten atheological arguments are presented (and briefly discussed) in each of which there is an apparently incompatible pair of divine attributes.
The Case for a Coherent God (n.d.) by Joseph A. Sabella
Sabella critiques each of the arguments sketched by Drange.
The Coherence of God: A Response to Theodore M. Drange (2003) by Ralph C. Wagenet
Wagenet argues that the arguments sketched by Drange do not prove the incoherence of the Christian god.
Oppy presents a logical argument based upon an alleged fact of metaethics: the falsity of moral realism. If moral realism is false, then that is a fact that is incompatible with God's existence.
If you want to be able put across a rigorous and convincing argument, you should read this document. Recommended for anyone who is going to be involved in debate or discussion. Included is a list of common fallacies to beware of.
Logical Arguments from Evil [ Index ]
An index of all articles in the Modern Library related to logical arguments from evil.
Bradley argues that the God of the Jewish and Christian scriptures are incompatible with a known fact. What is the known fact? (a) That it is morally impermissible for anyone to commit, cause, command, or condone acts that violate our moral principles. Why is the God of the Jewish and Christian scriptures incompatible with that fact? Because (b) according to Judaism and Christianity, any act that God commits, causes, commands, or condones is morally permissible. Furthermore, (c) the Bible tells us that God does in fact commit, cause, command, or condone, acts that violate our moral principles. According to Bradley, (a) is incompatible with (b) & (c).
Moral Realism and Infinite Spacetime Imply Moral Nihilism (2003) (Off Site) by Quentin Smith
Smith argues that if the future is infinite, as contemporary astronomers believe it is, then moral nihilism is true if both moral realism and aggregative value theory is true. He then argues that this conclusion implies that God does not exist. Thus, Smith's argument may be reasonably classified as a logical argument from moral nihilism to atheism.
If God is omniscient, it seems that he would have to know what it is like to learn. However, in order to know what it is like to learn, one must have learned something. This entails that at one time we were in a state of not-knowing a thing that was learned, then experienced what it is like to learn. But if God is essentially omniscient, he always is and has been omniscient, so was never in a state of not-knowing. Because being in a state of not-knowing is necessary to know what it is like to learn, we would seem to have to say that God does not know what it is like to learn. But this contradicts the original claim that he does know this based on his omniscience. Thus, it seems that God's omniscience generates a contradiction. Consequently an omniscient God cannot exist.
Jordan Howard Sobel's Logic and Theism is long, abstruse, and technical, but valuable for those who have an interest in its topics. Those looking for arguments based on empirical phenomena said to be best explained by the God hypothesis should look elsewhere. Sobel's focus is, rather, issues of definition and logical structure. He addresses everything from the ontological argument to the fine-tuning argument, demolishing all of the main arguments for God's existence. Moreover, he argues that the kind of omnipotence and omniscience that theists ascribe to God is incoherent, and defends both evidential and logical arguments from evil against the existence of God. Finally, he turns to a discussion of practical reasons for belief in God, such as those invoked by Pascal's wager. No cutting-edge research on these topics should omit Sobel's work.
Does God command what is morally right because it is right, or is it right because God commands it? If God commands what is right because it is right, then rightness appears to be determined by moral standards that are independent of God's commands, and that God himself is morally required to obey, calling into question his status as Supreme Being. On the other hand, if what is right is right because God commands it, then there are no moral constraints on what God commands, rendering morality completely arbitrary: even horrific actions would be deemed right. This modernized Euthyphro dilemma can be converted into an argument against the existence of the God of traditional monotheism, a sovereign creator. Although this Socratic argument does not refute God's existence as a Supreme Being, it nevertheless underscores a serious challenge to theists who argue that morality requires the truth of theism.
Note: the definition of a logical argument for atheism was taken from Paul Draper, "Evolution and the Problem of Evil," in Philosophy of Religion (3rd ed., ed. Louis P. Pojman, Wadsworth Publishing Co., 1998), p. 220.
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