The Abrahamic faiths, Judaism, Christianity, and Islam, all affirm monotheism, or belief in one God. These religions each give different answers as to the details, and those details are very important to the adherents of these religions; but together they share a tradition of asking the same or similar questions, and proposing the same or similar answers, about what, precisely, God is or is supposed to be.
Upon being asked what God is, it is natural for some to answer: "I don't know—no one knows. And that's as it should be. God is totally beyond the comprehension of mere finite beings such as ourselves, and we should not go about pretending that we can know what God is." There is something paradoxical about this position, namely, if one believes that the nature of God is totally unknown, but one nevertheless says that one believes that God exists, then one cannot even say what it is that one is believing in. Suppose a person states; "I believe that flibits exist, but I have absolutely no idea of what flibits are." This appears to be nonsensical. At least some minimal conception, therefore, seems required.
Even mystics, who believe that the nature of God is essentially mysterious to human beings, concede that one must have at least a minimal conception of God. If one has anything like a traditional Jewish or Christian belief, for example then in fact one does have some conception of what God is: God is an eternally existent spiritual being who created the world, and so forth. Many Christians further affirm: "There is the Father, Son, and Holy Spirit, so that there are three aspects to God, and while we may not know the precise meaning of this doctrine (of the Trinity), nonetheless we can know that it is true."
Philosophers know all too well, from dealing with for example the problem of substance and the problem of universals, that general "What is" questions (ti esti questions) give an overly simple appearance to what is in fact a very complex affair. The situation is no different with the question, "What is God?" What is it exactly that we are asking when we ask this? If all we wanted were a definition of "God," there are many of those available. What else is needed?
It is one thing to give the traditional sort of definition of "God," but it is quite another really to understand the terms used in the definition.
What follows is a typical definition of "God," which, perhaps with some adjustments, would be acceptable to many within the Jewish, Christian, and Muslim faiths:
Several aspects of this definition appear, to many thinkers, to need some explanation. There are two different kinds of questions we might raise about aspects of the definition. First, what do various important terms in the definition really mean? Second, how could we possibly get the very concepts of certain properties, described by those terms, properties which are not properties of anything in our ordinary everyday experience? What follows is a limited sample of problems. We begin by examining two relatively minor problems and then one much more important, overarching problem.
First, some say that God is eternally existent. Some theorists take this to mean that God is timeless—categories of past, present, and future just do not apply when we are talking about God. Others hold, instead, that "eternal existence" means that God exists at all times. In other words, if God is eternally existent, he has already existed for an infinite amount of time, and he will continue to exist for an infinite amount of time—his existence never began and will never end.
It is common to deny that we can understand God's eternity. Suppose we wish to deny that we can understand what an actual infinity is, and therefore we cannot understand what (God's) eternity is. In that case, part of what God is—his eternity—is something we cannot understand. Nevertheless, we want to have some notion of what God is that is adequate or robust enough for us to be able to say we understand what we mean when we say that God exists. The mere fact, if it is a fact, that we do not understand eternal existence, may not, by itself, be enough to show that we do not know what we are talking about when we say that God exists. Maybe we could still make sense of the claim, "God exists," without any clear notion of eternal existence, or maybe we could make do by understanding God's eternity by way of our closely related concept, of a potential infinity.
Second, we say that God is "all-powerful," or to say the same thing, omnipotent. Some philosophers have brought up some puzzles that are supposed to cast some doubt on whether the notion of omnipotence is coherent, or that are supposed to force us to rethink our notion of what omnipotence might be, anyway. The basic notion of being all-powerful can be understood well enough, it seems, at first glance: something is omnipotent, or all-powerful, if the being can do anything we can think of. But here is something we seem to be able to think of: a square circle. We may not be able to imagine a square circle, and of course, such a notion is self-contradictory. For all that, we do know what a square circle would be: a shape that is both square and circular. One might argue, then, as follows: if God can do anything, then he could create an actual square circle. But square circles, being self-contradictory, cannot exist. Does this mean that it is in God's capacity to do impossible things?
Along the same lines there is this hackneyed conundrum: would God's omnipotence allow him to create a stone that he could not lift? On the one hand, he is omnipotent, so he could create anything; but if he created this stone, then he could not lift it. It does not seem to solve the problem to say that, just as a matter of fact, God does not make square circles, or stones he cannot lift. The question, after all, is not whether God does such things, but whether he could do such things. The claim that God is omnipotent is, after all, a claim about what is possible, about what God has the ability to do, not about what is actual.
Many philosophers and theologians regard this puzzle about omnipotence as not a very serious problem. What they often say is that God can do whatever is logically possible. God cannot create contradictions, they say, but that is no real limitation of God's power. To talk about an actually existent contradiction is just nonsense, they claim; that God cannot create a stone he cannot lift, or that God cannot create an actually existent square circle, is not any serious limitation of God's power. So, they say, we could say that God can do anything that does not imply a contradiction.
Theologians and philosophers also debate a broader issue about the nature of God: how are we to understand what sort of thing God is? Consider these three things we say about God: first, God is a spirit; second, God is the creator of the world; and third, God exists apart from space and time. All three of those things are said, in the big monotheistic religions, of the same being, which gives rise to some puzzles about the sort of thing that God is supposed to be.
Consider the first claim, that God is a spirit, by itself. What does this term "spirit" mean? Please note: if we regard the above definition of "God" as a genus-and-difference definition, then the genus of God is "spirit," since God is a particular kind of spirit. The rest of the definition of "God" is supposed to tell us what kind of spirit God is. Therefore, on anyone's account, if we do not understand what spirits are, then we have no grasp on what sort of thing God is. So a great deal of philosophical and theological work on the nature of God surrounds the issue of the nature of the divine spirit and what its relationship to the world might be.
On one possible view, we might say that the word "spirit" means no more than mind. We might suppose we have a better conception of what minds are, because we are all (the private language argument notwithstanding) intimately acquainted with our own minds. We then, on this view, have a concept of what God is: God is a mind, like our own minds, only much more powerful. Now, those who say that God is a mind face special problems of their own. Let us now bring up the second and the third claims about God that listed above: God is the creator of the world, and God exists apart from space and time. On the view in question, then, it is a mind that created the world, and this mind exists apart from space and, significantly, time. But how can we understand what a mind is supposed to be that creates physical bodies out of nothing and which exists (on one conception of eternal existence) timelessly?
Skeptics and mystics point out that we cannot really understand what it means for a mind to create anything physical. We do, they say, have a notion of what minds can do, based on observation of our own minds. Our own minds can think thoughts, perceive the world, experience feelings, and make decisions. The decisions we make result in the actions of our own bodies. The only way in which we are familiar with minds impacting the world is via the bodies that are associated with those minds; in other words, it is only when we decide something, or have a strong feeling that causes us to act out of excitement or anger, that our minds cause our bodies to act.
But now compare that with what is being claimed about God. God is supposed to be a spirit, which, on the view under consideration, is a mind, albeit a divine mind; this divine mind is supposed to have created physical objects, the physical objects that make up the universe, out of nothing. We certainly do not have any experience of minds creating physical objects out of nothing; from a first-person perspective, we surely have no experience or idea of what that would even be like.
Now, suppose that we do understand the notion of a mind creating something out of nothing. We imagine someone thinking very hard, with nothing in front of him; and then the next moment there is something, like a tree, in front of him; and, whatever this would mean, we imagine that his thoughts have caused the tree to appear in front of him. And remember, since God is supposed to be just a mind, without a body, that we shouldn't imagine a human being sitting there and looking like he's concentrating hard just before this tree pops into existence. That wouldn't be an accurate representation of the situation. We would have to imagine a mind, somewhat like our own mind, all by itself causing the tree to pop into existence. Now, we may be able to imagine this, in a way; but the question is whether we really are imagining a mind creating a tree out of nothing. Because, when we get to the part about a particular decision that causes the tree to appear out of thin air, we draw a blank. We have absolutely no experience of anything like that sort of decision. So one would doubt that, in fact, what we really are doing is imagining the creation of the tree with a mere decision.
So that is one problem about the notion that God is a mind—namely, it is hard really to understand the very notion that a mind can create physical objects out of nothing. We might imagine that we understand this, but it doesn't seem like we actually do.
But now another problem about the notion that God is a mind arises. We said that God exists eternally, and that "eternal" has two different interpretations, meaning either existing timelessly or existing at all times. But suppose, as many people do, that God's mind exists timelessly. In other words, when one thinks about what this divine mind is supposed to be, one can't apply normal categories like "past," "present," and "future" to it. God's mind does not pass from earlier thought to later thought; it doesn't make plans and then, later, act on those plans. To say those things would be to imply that God's mind does not exist timelessly.
But this makes the very notion of the divine mind exceedingly strange. It does not remotely resemble how we understand what our own minds are: they are, as far as we can ascertain, a series of experiences, thoughts, judgments, feelings, decisions, and so forth, coming one after another. We are saying that God's mind, or rather the mind that is identical to God, has no such series of thoughts, decisions, and so forth. Because the divine mind is timeless: the categories of before and after simply don't apply to it. Hence, it is difficult to say that the divine mind even has such things as thoughts and judgments, because a thought, in any sense of this word that we are familiar with, is, presumably, something that has a beginning and an end. God's mind is sitting in the same state for all of eternity. A very complex, grand, incomprehensible state. So it becomes a daunting task to demonstrate that this state, or any part of it, has thoughts or decisions, etc.
Other problems arise with the supposed interaction between a timeless "spirit" or state and our worldy existence. Ordinary traditional Christianity, for example, holds that we can pray to God and God answers prayers; that God speaks to prophets and perhaps even to us individually, sometimes; and so forth. But in order for God to do these things, God must, at least in some sense, exist in time.
The claims about God don't seem to lend themselves to a coherent picture. God is supposedly a mind, but this mind differs radically from the human mind, because, first, it has the ability to create physical objects out of nothing, through thought alone; and, second, it does not have any series of thoughts at all, but remains in the same mental state, apart from time, or as it were throughout eternity. And yet, straining our powers of interpretation, God is supposed also to perform individual acts, such as doing miracles and answering prayers, at particular times. Those, at least, are the claims stemming from the basic notion that the sort of thing that the divine spirit is, is a timeless, creative mind.
But then is this "being" a true mind if it has little in common with what we know to be minds? If God is in a single state throughout eternity, and with a pure spiritual act it can create a tree, then surely it would be, as Hume says, an abuse of terms to call God a mind. Minds have successive thoughts—thoughts that succeed one another—God is no such thing. God is supposed, at least by many people, to be unitary, simple, and unchanging. And so we would be most accurate not to call the divine spirit a mind.
We can say that God is a spirit, but it does not seem fair to call it a mind. What, then, is a spirit, if it isn't a mind? Do we have a concept of this non-mental spirit, and if we do, how did we come by this concept?
Throughout history, people have claimed to see visions of God or have claimed to go into mystical ecstacies and so forth by which they procured some understanding of God. But it seems that such experiences are not publicly knowable by ordinary people. It is thus difficult to understand how words like "god" and "divine" have gotten into our language game, if it is believed that they are only knowable by way of mystical experience. People who say they believe that God exists, but who also believe that we cannot have any concept of what God is, except by a very unusual sort of experience, are known as mystics and their view is called mysticism. The unusual sort of experience which they say gives them some insight on the nature of God is called a mystical experience.
However, mysticism seems to imply that the concept of God is not broadly accessible. If the only way to come by any approximately coherent conception of God is via a mystical experience, then it seems as though this formulation of God hasn't got enough objectivity to get it off the ground. An alternative description of God is that he is not "timeless," but that he does have successive thoughts, feelings, decisions, and so forth. That is, after all, more consistent with many elements of a traditional faith.
This point of view on the nature of God may be described by a term often contrasted with "mysticism," namely anthropomorphism. The term "anthropomorphism" comes from two Greek words, anthropos meaning man, and morphos meaning shape or form; so "anthropomorphism" describes any belief according to which something non-human, such as a god, an animal, or a plant, is thought of as being like human beings. Very few believe that God has a human body, but many people historically have believed that their gods had bodies and that those gods could roam the earth. We could use the phrase "physical anthropomorphism about God" to mean the belief that God has a body. But then we might also use "spiritual anthropomorphism about God," meaning that God has a mind something like a human's.
The idea then is that we get our concept of God's qualities—his ability to create, his knowledge, his feelings for us, and so forth—by analogy with experience of our own minds. Of course, even the anthropomorphite isn't going to say that God's mind is exactly the same as a human mind. There are some extremely important differences, but God's mind is supposedly enough like our minds that we can make good sense of the claim that God is indeed a mind.
A fundamental characteristic delimiting what sort of entity we are talking about when we discuss God is that of will. God can be described as the entity for whom will does not translate into action, but for whom will is action.
Proof evidenced an a priori question. Can an a priori God be proven? Philosophers have attempted to disprove God in nature, by arguments of different theories as relating to design, existence of common life and alien life forms, the mathematical and empirical basis, the theoretical improbability and other complicated mind bogging ideas. Just so, all the negative results obviously sum up a need for positive proofs. Are any such positive positions or theories possible? One such proof was the ontological argument, which posits that the definition of God implies His existence. Its efficacy as an argument is still up for debate.
Originally based on lecture notes by Larry Sanger.