The simple definition for a theist is someone who believes that God exists. Put the letter "a" before it to denote "not," and you get an atheist: someone who does not believe in the existence of God. If atheism were that simple, there might be a lot less confusion, but alas, that is far from being the final word on the issue. When someone speaks about atheism or claims that they are an atheist, it is far too general a term to carry with it many assumptions.
For example, someone may very well not believe that God is anthropomorphic. The idea of godlike anthropomorphism basically means that God has qualities that are very humanlike, or qualities that humans share with God. There is the well-known notion among Christians that God made humans in his image, and this is a good illustration of an anthropomorphic conception of God. The anthropomorphic God may have characteristics such as personality, like feeling love and anger, as well as sentience. The Greek Gods may be even better examples, because they were described as having the entire spectrum of human emotions from the most virtuous to the most vile.
But imagine someone who does not believe that God is anything like humans at all, but is rather some sort of force that created the universe but has since left it (perhaps expired itself). Is this person an atheist? Must an atheist reject every form that theism takes to still be considered an atheist? The answer is: only if one wants to be considered an atheist is one an atheist. Titles and the endless forms of religious "isms" are designed to make things clearer for us, and yet so many times they serve only to confuse us. If someone calls themselves an atheist, and if you want more information than that, you're simply going to have to ask them for a more detailed description.
Thankfully, there are typical forms and general traits that atheism takes which will anchor this discussion. To put it simply, the typical atheist, when presented with the ideas and description of God, rejects that such a notion is viable. We make similar decisions and judgements all the time about a myriad of things. If something perplexes us, we desire solutions. Sometimes other people offer us their version of what that solution is, so we must then assess it personally. If we can't accept that solution, we move on and look for others. All humans are similarly faced with a fundamentally perplexing philosophical issue, namely, what the true nature of the world is. The answer to that question will probably affect the way we choose to act within it, and the search for it will depend on how we personally understand life and reality to be.
Christian theists offer one possible explanation for the events in the world: that there is a god in the universe whom they call God, and with the belief in God comes a great variety of possible implications (that can vary, but often include the existence of an afterlife, definite conceptions of good and evil, that the universe is orderly, not chaotic, etc.). We will analyze some of these implications later, but suffice to say that the belief in God is an explanation that many people offer and, in turn, many people accept. Atheists are also offered that particular solution and opt not to accept it as an answer to their questions. They instead decide to look elsewhere.
Why would some people accept God and not others? One could dismiss such a question by answering with the phrase, "there's no accounting for tastes." But luckily the decision to believe or disbelieve in God for cognizant thinkers is not quite so arbitrary as a mere personal preference (though preferences often weigh heavily). When someone considers the existence of God they must consider both the reasons for believing in God and the implications of that belief. If they find the reasons to be poor, that may convince them that the explanation is faulty. Similarly, if they find the implications of the explanation absurd, destructive, or impractical, it may convince them to move on.
This is a good time to consider some of the most popular reasons theists have given for accepting the belief that God exists. I will briefly describe some of these classical and well- known arguments, and then I will make my own assessment of them. You should be immediately aware that I have already made my decision on the issue, at least at this time; I am an atheist, after all. That means I will explore some faults in the reasons I am about to describe, but I will try not to let my personal opinion overpower the overall consideration. It is your opinion that matters right now.
The Ontological Argument
This argument is famous because it is one of the first and yet one of the more intriguing arguments for the existence of God. The argument is posed by Saint Anselm, who lived primarily in the 11th century (1033-1109).
When many of us desire proof or confirmation of something, we look for evidence. For example, in a mystery novel the master detective seeks solid clues that might reveal the solution to a given problem. This conjures images of looking for fingerprints, searching for evidence and the like; anything that might bring the truth to light. That is usually how we as Westerners go about bringing philosophical truth to light as well. We look for solid clues in the world and try to put them together hoping to make sense of the mystery. But the point is we look for physical clues, something that is outside of ourselves and something we can gather with one or more of our five senses. We usually espouse empiricism, which, in a simple form, means that we believe many pieces of knowledge are found only through experience, such as by encountering them with the senses.
Anselm was one such philosophical detective who attempted to prove his belief that God exists, but by means that may be considered somewhat unconventional by modern standards. He claimed that God could be proven without ever looking beyond or outside oneself. He focused on means that are called a priori, that is, purely rational and mental feats without any reliance on experiences or the senses. By thought alone he tried to show that God exists, and here is how he tried to do it.
Anselm, in his work Proslogion, wants to know what the greatest, most perfect notion the mind can conceive of is. He felt that the mind can conceive of such a thing that no greater thing can be conceived, which means that no other thing can be considered greater than this thing. We can imagine an entity of unlimited power, unlimited knowledge, who created everything, who cares infinitely for us, and so on. This is indeed a powerful notion, and such a thing would have nothing more powerful than it in any sense. But is it truly the greatest thing that we can think of? Anselm felt that there still exists something greater than this outlined notion. For all of this entity's greatness in our imagined conception of him, a greater conception would be one that was not imagined at all. The greatest conception the human mind can formulate is this same entity that we just imagined, but who is actually a real entity as well, not just imagined. Therefore the mental notion of this being of which no greater thing can be conceived must really exist, or else it wouldn't be the greatest.
Anselm asserts that God is that thing which no greater thing can be conceived, and since he has shown that God fulfills this definition, this thing must be real; Anselm concludes that he has shown that God exists. But does something seem confusing? Is Anselm's reasoning correct, and are his premises true?
Anselm's argument is rather bewildering, perhaps, in that it is so conceptual. I think that even my summation of it above is a bit thick and confusing. Maybe this is partly because Anselm uses that a priori style I described earlier, which many of us are not acquainted with, and his language and formal argument seem rather dense. Still, we have to try to put our temporal differences aside (a nine century difference no less) and assess his argument as objectively as we can.
But before we can do that, do we accept that it is a good move to use mental reasoning alone to prove such a matter as the existence of God? In this day and age, it's a lot harder to swallow, and here we may be unable to resolve our temporal differences with Anselm. Anselm came from a time when the accepted beliefs of intellectual thought gave more credibility and weight to matters of the mind, not those of the outside world that we observe through the senses. When I say "mind," I do not mean the modern concept of the human brain. I mean what Anselm and most of his historical contemporaries meant; this human apparatus that may or may not stand apart from our physical body and senses, which conceives, imagines, and wills. These are not activities that the body does (at least not superficially), like walking and hearing sounds.
The mind was once considered a purer philosophical subject to these thinkers, and the abstract ideas it dealt with were considered purer objects than what we sense. After all, though the body and senses are certainly useful, they are inclined to err and deceive; eyes can be tricked by illusions, and the body can dream, become ill, and grow old. The mind acts upon reason that seems invulnerable to such deceptions and conditions. Think of mathematics; it is something which is purely theoretical by itself, yet it is so systematic in its axioms and calculations that it seems inviolable. But can you touch numbers? You can touch numerals that are written on a piece of paper or typed upon a screen, but numbers themselves just aren't physical in any way. Numbers are purely abstract, and only our minds can discover their wonderful, useful truth.
It is no wonder that Anselm sought to prove God's existence by mental means rather than physical ones. But we must consider our modern perspective that generally gives our senses and objects in the physical world more credit. We usually perform a different form of detective work than Anselm, and the question again is this: despite how thinkers of Anselm's time viewed rationality and the senses, does Anselm succeed in his attempt to use purely rational means to prove God's existence?
His argument is remarkably slippery. Anselm surely did not try to trick us by using some strange conceptual sleight-of-mind, but nonetheless, something seems to be astray in his reasoning, and I will try to explain what I mean. First of all, Anselm's initial desire seems acceptable. He wants to find something of which no greater thing can be conceived, and although I might say that such a pursuit might prove difficult to articulate, I am willing to follow Anselm along to see where it leads.
He then posits that something conceived of as being real is better than that same thing being conceived of as being just imagined. This too I can follow, for certainly if I was offered an imaginary gold bar or a real one, I would take the real gold bar. Why? Because something imaginary may be fine and good, but if that same thing is actually real, I can then really have it, handle it, and use it. It matches almost every intuition of mine to think of something as better when it is real as opposed to just imaginary -- except perhaps for some vile things, like excrement or disease. But since we're not talking about something vile when we talk about God, I have no problem accepting the premise that it is better to be real than to be purely imagined or conceptualized.
Anselm then states that that thing which nothing greater can be conceived of must be real rather than merely subjective if it is in fact to be the greatest. Conceptually, that seems to be true, because it would clearly be contradictory to think that this imagined thing, God, which is the greatest conceivable thing, could even possibly have this sort of twin brother who is just like him in every respect except that he actually exists; how could the imagined God be the best when the same God that is also real exists as well?
Nonetheless, there seems to be a step missing here that is fundamental to the argument. Anselm is using "conceiving" and conception throughout the entire discussion until the very end. Conceiving of something of which nothing greater can be conceived is viable; then deciding that conceiving of something real is better than conceiving of that same thing as being imaginary is also viable. But how did Anselm move from the conceiving of something real to it really being real? Perhaps Anselm would say that I misunderstand him. When he said that something real is better than that same thing as being subjectively imaginary, maybe he meant that it must be absolutely real, not just conceivably real. Couldn't Anselm just say that it is better to exist necessarily than just possibly? In fact, Anselm makes that very point. That seems true enough, and if it's true, then God must exist necessarily by the same reasoning used to show that he is real.
Anselm is engaging in a thought-experiment; that is, a mental exercising of a notion about a sort of "what if" situation. But he is taking his hypothetical mental exercise and pushing it into reality. I still have my doubts about whether such a step is valid, even given the maneuvers he is attempting to use. But even if such a move turns out to be valid, couldn't we prove an infinity of other things the same way?
Luckily for us, a contemporary of Anselm's named Gaunilo posed that very last question elegantly. He imagined trying to conceive of the best island of which no greater island could be conceived, calling it the 'Lost Island.' We can conceive of this island as well; it would have great proportions, infinite fortitude, plus whatever else we want to conceive it as having, like riches and beauty. But this island would still be conceivably inferior in the imagination alone than it would conceivably be in reality. So the best conceivable island must have whatever qualities we ascribe to it and it must conceivably be real, given Anselm's own reasoning. But that simply seems absurd, because the 'Lost Island' just doesn't exist, and we know that because Gaunilo intentionally made it up. It seems as if we could do the same thing with anything at all; the best castle, the best student, the best copy of Gentle Godlessness, or the best unicorn. But it seems very wrong to think that this proves their existence.
Anselm replies to Gaunilo the following way: the reasoning used to prove God's existence can only apply to one thing: God. Notice that the 'Lost Island' was defined as the greatest island of which no greater island can be conceived. But God is the greatest thing of all things, and among anything you want, nothing is conceivably greater; that means that God is great without qualification. We have to qualify the 'Lost Island' as best among islands, and that makes it pale in comparison to God. An island is not eternal like God, nor can it exist everywhere in space at once like God supposedly can. Even if you revise the 'Lost Island' to be eternal and omnipresent, you are still left with two problems: how do you still know it's an island, because it doesn't look like one now; and even so, isn't it better to be alive then dead? If the 'Lost Island' isn't alive, it's imperfect by lacking rationality which we think is clearly better than its absence. But if you give the Island life and reason, doesn't it just become God with a different name?
Frankly, I still believe Anselm is taking an extra step in this argument, and there may be room to show how. Ultimately, the hinging premise is that God is that thing which no greater can be conceived. At first, it may seem that if you do not define God as something which no greater thing can be conceived, Anselm's argument falters right away. But since most theists do believe that God is this conceivably greatest thing, if not in those exact words, it seems a little unfair to Anselm to dismiss that premise that easily. But at the same time, many people do not accept that premise at all. There is an important difference between a conceptual definition and a definition that defines something all people accept as real. I know what the definition of "grue" and "fairy" is, but their definitional powers are limited by their metaphysical existence, which in their case, is just imaginary or just conceptual. Since their definitions are merely conceptual, to use them as fundamental premises in a metaphysical argument seems to beg the question. Similarly, it seems that we must beg the question and assume that God is that thing which nothing greater can be conceived, not just conceptually but metaphysically, before the definition can complete its work in Anselm's argument. If such a definition is accepted, there is little point in using it in trying to prove God's existence when the definition itself requires his metaphysical existence already.
So I still suspect that Anselm has yet to move from the hypothetically best conceivable thing to what he wants, the really best conceivable thing. One can agree with everything Anselm says - -that God would have to be eternal, omnipresent, and real to be the greatest-- and still say, "but this thing isn't really real; it would have to be real, though, hypothetically."
But ultimately, my criticism falters. Anselm's argument is difficult to assess and to address, and though one's gut reaction may be that it still fails, it is hard to reasonably pinpoint exactly where Anselm goes wrong, if he goes wrong at all. I suspect very strongly that Anselm has smuggled into his definition of God more metaphysical meaning than the innocent bystander really thinks they're committed to. But since I do not think that I can properly justify my suspicion, at least not here, Anselm potentially stands fairly well.
There is one thing I find solace in, however: that despite Anselm's argument, it is an argument you will rarely find a theist using to justify or defend their belief. Other arguments hold greater force because they are both easier to understand and because they make more sense on an intuitive, human level. Anselm's contemplation is intriguing, but it is a bit unwieldy. Anselm already believed in God before he endeavored to prove God's existence, so Anselm obviously did not need this argument to make his belief viable for himself. The argument was simply meant to provide support. Even Gaunilo, who offers wonderful responses to Anselm, believed in God externally to the discussion of the argument. By itself, however difficult to fully grasp or refute, I'm sure the ontological argument generally fails to convert anyone.