This is the first of two arguments for the non-actuality (read: existence) of God taken from some work I did last year. In that period of time I've read them over a few times, and think I can present them more analytically now. The more time you spend thinking about certain areas in philosophy, the more rubbish and noise you can sieve out. I will write about the second argument at a later point. (I think the second one is probably stronger) I should also note that I first read an argument of this form by John Mackie, and it’s the sort of thing that has probably existed as long as Theism itself.

Both arguments use the same logical form, which goes as follows:

P1: If God exists then He has properties A,B,C.

P2: If God had properties A, B, C then He would act in X-fashion.

P3: If God had acted in X-fashion, we would observe Y.

P4: We don't observe Y.

C1: Therefore God didn’t act in X-fashion.

C2: Therefore God doesn’t have properties A,B,C.

C3: Therefore God does not exist.

The argument is valid. All that remains is to fill in the gaps and attempt to justify the premises. So for each argument I will need four separate premises. If I need to give new arguments for some of the premises then I will use "L" for "lemma", so as not to confuse them with the premises of my main arguments.

Argument 1

P1 If God exists then he has the properties, omnipotence and omnibenevolence.
P2 If God has the properties omnipotence and omnibenevolence, then He would create no Evil, and would not allow any Evil to exist that He has not created. i.e. there would be no Evil. That is: If there were no Evil, then we would observe no Evil.
P3 If God had acted as specified in P2, then we would observe no Evil.
P4 We don't observe no Evil. (We observe Evil.)

P1 is analytically true, in virtue of the meanings of the words in the premise. This is simply a definition of "God". Anybody who disagrees with me on the truth of P1 is talking about some other concept "God", and we are talking past each other.

P2 requires some reasoning, and there will be room for a theist to deny it. I will discuss objections to P2 in the next paragraph.

P3 is true and I shall argue for it here. Let's just consider what would make it false. For P3 to be false there would have to be no Evil, but we would still observe Evil. In the sense I am using the term "observe", an object does not necessarily have to exist for it to be observed. For this to be the case, one of two scenarios would have to be true:
1) We don't know what Evil is.
Suppose we think that Evil is a kind of bird, and we see these birds flying around and some of us conclude, "Bah! God can't exist because these birds exist."
2) We don't observe the world as it really is. There are birds but we don't see them.

Now I want to reject 1) immediately. Some theists might say in response to this argument as a whole and other arguments, that if God does something then that thing is good. If God murders people, then people being murdered becomes good. In other words, we don't know what the meaning of "good" really is, besides "the things that God does or might choose to do." People who say that are really thinking of some other concept other than goodness. Most of us have the intuition that if God raped babies purely for fun He would be doing something bad. We know what Good and Evil are, so 1) is to be rejected.

Now 2) is a real possibility. A theist might say, "Well actually, I know it looks like there is Evil, but actually there isn't. You are a brain in God's vat. You might perceive the world correctly in some areas, but wrongly when it comes to ethical events. You see somebody crying in pain but actually they have the mental state of happiness."

The problem with that seems to be that if I observe some unnecessary pain, for example somebody crying because an earthquake destroyed their house, but really they are happy at that fact (or maybe they've really perceived their house having a new extension built onto it?), it still causes pain in me to see it. Some of that "Evil" washes over into my own mental state, and I can be reasonably certain that the contents of my mental states are really happening.

A third way for the theist, I haven't properly mentioned yet, is the argument that all so-called Evil in the world, is really necessary. For example, we might think it bad that we feel pain when we graze our knee, but we would not will that the pain went away. Imagine being such that your knee is grazed and you don't feel the pain. We need pain to tell us that our body is injured and without that knowledge we would have a poor survival rate. So we analyse pain as being a necessary evil in the actual world. But in a world with God in it, why could He not have just made us immortal in the first place? We wouldn't need to suffer pain or injury then. But is a world without any unnecessary evil metaphysically possible? I can conceive it but that doesn't make it possible (necessarily). The thing is that it does not have to be possible. I'm fairly certain (using my modal intuitions) that a world is possible that has slightly less Evil than this world. Only the possible world with the least Evil in is a candidate for a world with God inhabiting it.

There are two final tenable positions for the theist (and by "theist" I mean the theist who believes in the sort of God I am describing, e.g. somebody of the Abrahamic religions). The first is some kind of Fatalism, whereby there are no possible worlds other than the actual world, and therefore the actual world has the least Evil in it of all the possible worlds. But this sort of view is simply inconsistent with our basic intuitions. I think I know things like "Possibly I could have got up earlier this morning". Fatalism is inconsistent with agents being responsible for their actions, which is something that these very deranged theists sometimes forget. It really isn't consistent with a lot that we find extremely intuitive.

The second possibly tenable position is that all worlds necessarily have equal degrees of Evil in them. This is a completely new view of Goodness, but not a necessarily unintuitive one. This analysis of Goodness might say something like: Suppose there is a possible world identical to our own but where there is some new species of maize which grows in the desert, and therefore there is far less hunger than in the actual world. This doesn't mean that there is more Good in this possible world (even supposing that less hunger is a relatively good thing), because the standards for Goodness of the people in that world shift as a result of there being seemingly more Good in it. Really, there is always an equilibrium of Good to Evil in any possible world, just in virtue of the meanings of those worlds. In some worlds that resemble Heaven, the worst parts of those worlds are when agents choose not to hold doors open for others. In worlds that resemble Hell, the most apt instantiations of Supreme Good are times when the Devil only whips you a thousand times a day. Goodness and Evil are relative concepts. This whole analysis of Goodness falls apart however. If we really thought this way, then why would we ever act at all? Surely we act so that we can bring some more Good into the world? The game of experiencing Goodness isn't zero-sum. If it were then we may as well be dead than eat that Belgian Bun on the worksurface. It all means the same anyway. We clearly don;t think like this, so I have tor eject this (also Fatalistic) analysis of Goodness. I think that that caters for all the possible lines of attack of the reasonable theist.

P4 is as well-supported as P3. We observe Evil and we know this because it is being presented to us in terms of a mental state. It is one of the things we can be most sure about.

Overall, I think the premises of this argument are very well-supported. I originally thought this argument to be slightly empirical, but it's about as slight as one can even imagine. One of the beliefs we are most justified in believing is that we exist. Our existence is only supported by the fact that we are experiencing some mental state. We can't falsely be experiencing a mental state. (Or at least if you deny that, you ought to have a damn good reason to)