Anthropomorphism - To think of God as like a human being, only more perfect, is to anthropomorphize God. More generally, to consider any being or object in human terms is to anthropomorphize that being or object.
A posteriori - An a posteriori truth is a truth that is arrived at by observing the world. An a posteriori argument involves gathering evidence from experience and reasoning from that evidence. For example, the fact that John has blonde hair would be a truth that we can know based on a posteriori reasoning. The fact that heat is molecular motion would be another such fact. Many philosophers claim that all substantive facts about the world are a posteriori, and that all arguments for substantive facts must be a posteriori arguments.
A priori - An a priori truth is one that can be arrived at without any observations of the world. A priori reasoning relies only on logical connections between ideas. For example, the fact that all bachelors are unmarried is an a priori truth because being unmarried is in the definition of the idea of a bachelor. In order to determine that this claim is correct you do not need to go out into the world and survey all bachelors. Rather, so long as you understand the meaning of the words involved, you know that the claim is true. Hume believes that all a priori truths are such that the predicate ('unmarried') is in the definition of the subject ('bachelors').
Argument from design - The argument by design claims that the order and beauty of the universe are proof that there is an intelligent designer behind its creation. Cleanthes uses the argument by design to prove that we can infer God's nature from the world. See also empirical theism.
Argument by analogy - An argument by analogy seeks to draw a conclusion by claiming that the phenomenon under question is analogous to another, better known, phenomenon. Usually, the phenomenon under question is an effect and the argument seeks to establish its cause. By saying that A is analogous to B, we can conclude that A's cause (which is unknown) is analogous to B's cause (which is known).
Cosmogony - Cosmogony is the branch of science that seeks to understand the origins of the universe.
Deist - Deists believe that they can rationally prove that God created the world but He has exerted no control or influence over his creation since the moment of creation. See also theist.
Demonstration - A demonstration is a deductive argument. It consists of several premises leading logically to a conclusion. A demonstrative proof is a certain proof: so long as the premises of a demonstration are true, the conclusion cannot possibly fail to be true.
Empiricism - "Empiricism" is a collective name given to a variety of philosophical doctrines concerned with human knowledge. Empiricists generally believe that substantive knowledge requires experience, and that there is no knowledge that human beings are born with. In addition to David Hume, some associate John Locke, George Berkeley, Thomas Reid, Rudolph Carnap, G.E. Moore, and W.V. Quine with Empiricism.
Empirical theism - Empirical theism is the position that religious belief can be rationally grounded in experience. An empirical theist believes that by looking at the physical world we can come to an understanding of God and his attributes.
Enlightenment - The Enlightenment was a philosophical movement during the 18th century that sought to examine all doctrines and traditions using the faculty of reason.
Epistemology - Epistemology is the branch of philosophy concerned with knowledge. Epistemological questions include: What is knowledge? How do we form beliefs based on evidence? Can we know anything?
Ethics - Ethics is the branch of philosophy that studies how people should act. Ethical questions concern the nature of good and evil, and the proper behavior of man.
Evidentialism - Evidentialism is the position that holds a claim to be valid if and only if it is supported by sufficient evidence. Hume was an evidentialist.
Fideism - Fideists hold that religious belief cannot be grounded in reason because there cannot be sufficient rational arguments for the existence of God. Thus, religious belief must be grounded in irrational faith. Fideism sees philosophical skepticism as the first crucial step toward Christianity, because skepticism undermines one's trust in reason and opens one up to pure faith.
Inductive inference - In an inductive inference we form a conclusion regarding unobserved events based on the evidence provided by observed events. For example, if we repeatedly see event A followed by event B, then the next time we see event A we might predict, based on an inductive inference, that B will follow. Similarly, if we see B we might infer that A preceded it. Either one of these (from cause to effect and from effect to cause) counts as an inductive inference.
Metaphysics - The branch of philosophy concerned with the objective structure of the world. Questions about God are metaphysical questions.
Moral attributes - God's moral attributes are the attributes that God has insofar as he is a moral agent. God's moral attributes include his goodness and his will.
Natural attributes - All of God's attributes other than moral attributes are his natural attributes. God's natural attributes are the attributes he has insofar as he is an existent being. God's natural attributes are supposed to include infinitess, perfection, unity, and incorporeality (i.e. the fact that He has no physical body).
Natural Religion - Natural religion comprises those religious beliefs that any rational person can obtain by looking at the evidence and using their faculty of reason. It is contrasted with revealed religion (or revelation), which comprises those beliefs that can only be obtained through certain supposedly divinely inspired sources such as the Bible, the Torah, or the Koran. Hume's purpose in the Dialogues is to show that there is no possibility of natural religion. There are no religious beliefs that we can obtain purely by gathering evidence and reasoning about that evidence.
Ontological argument - The ontological argument is an a priori argument which is intended to prove God's existence. There are many versions of the ontological argument, all drawing on the supposed fact that the idea of God cannot admit of nonexistence. The version found in the dialogues goes as follows: (1) Every effect has some cause. (2) Therefore, there must either be some ultimate cause that is necessarily existent or else there must be an infinite chain of causes. (3) There cannot be an infinite chain of causes because then there would be no cause to explain the existence of the chain itself. (4) Therefore, there must be some necessarily existing being, i.e. God. Another famous version of the ontological argument can be found in the work René Descartes.
Probabilistic argument - In a probabilistic argument the premises only guarantee that the conclusion is likely to be true, not that the conclusion is definitely true; even if all of the premises of the argument are true, the conclusion could still turn out to be false. Inductive inferences are always probabilistic arguments, while deductive inferences are never probabilistic. See also demonstration.
Rationalism - "Rationalism" is a collective name given to several philosophical systems marked by similar strains. Rationalists tend to believe that reason is extremely powerful, and that by using it we can come to know almost everything that there is to know. They also tend to believe that we can obtain substantive knowledge about the world without investigating the world at all (but, rather, just by thinking about the concepts that we are born with). The most famous rationalists were René Descartes, Baruch Spinoza, and G. W. Leibniz.
Revelation - Also called "revealed religion", revelation is supposed to be contrasted with natural religion. Whereas natural religion is comprised of those religious beliefs that can be arrived at through reason, revelation is comprised of those religious beliefs that can only be found in certain supposedly divinely-inspired texts, such the Bible, the Torah, or the Koran. These religious truths are supposed to be accepted on the basis of faith (i.e. the faith that the author of these texts was God himself).
Teleological - A teleological explanation attempts to account for states, events, or things by appealing to a notion of purpose or goal.
Theist - Theists believe in a personal God who concerns himself with human affairs. See also deist, empirical theism.