Ryan Peterson asks:

What is wrong with the argument that one can’t ever be certain that god exists or does not exist, becuase one would essentially need to know everything.

Arg, do you know what argument I’m trying to formulate? Becuase after hours of studying it’s hard to put my finger on it. If you know what I am trying ask…. :-) …..and want to answer it, that would be great… :-)…!

I wasn’t familiar with the argument in question, but some searching quickly lead me to this page on the argument from omniscience. (Ryan confirmed that to be the right argument.) Essentially, the question raised by the argument is “Is omniscience required to deny the existence of God?” Here’s the theistic argument, as well as the standard atheistic response:

Myth: The only logical basis for atheism is to know everything — in other words, to be God!

Response: It isn’t too uncommon for some theists to argue that logical, reasonable atheism requires such extensive knowledge that an atheist would have to actually be God in order to deny God. Here is an example once seen in the forum:

In order to be a real atheist, you would have to be everywhere, and have seen every part of the universe, to KNOW or not believe there is no God.

The Let Us Reason Ministries website expresses the same idea:

To be a Atheist one would have to be omniscient knowing all things having a perfect knowledge of the universe, to say they absolutely know God does not exist. For one to do this they would have to personally inspected all places in the present known universe and in all time, having explored everywhere seen and unseen.

Here is a slightly more sophisticated version from Hank Hanegraaff:

Atheism positively affirms that there is no God. But can the atheist be certain of this claim? You see, to know that a transcendent God does not exist would require a perfect knowledge of all things (omniscience). To attain this knowledge you would have to have simultaneous access to all parts of the universe (omnipresence). Therefore, as an atheist, to be certain of this claim you would have to possess Godlike characteristics. Obviously, mankind’s limited nature precludes these special abilities. The atheist’s dogmatic claim is therefore clearly unjustifiable. The atheist is attempting to prove a universal negative. In terms of logic this is called a logical fallacy.” (quoted from The Free Mind: The Newsletter and Forum of the University of Minnesota Atheists and Humanists 2(7), May/June 1996.)

This argument rests upon a couple of common misunderstandings. First, it makes the mistake of assuming that an atheist, to be an atheist, must have certain knowledge that no God or gods exist. Although some atheists may certainly make this claim, it is not necessarily true of atheists generally. As discussed elsewhere, atheism is simply the absence of any belief in the existence of any gods. To simply lack theism, it is not necessary for an atheist to be either omniscient or omnipresent.

Second, even if an atheist denies the existence of some particular god or all possible gods, it is not necessary for the atheist to claim absolute certainty. Rationally justified beliefs can be, and often are, based upon evidence which falls short of absolute certainty. We aren’t absolutely certain that the sun will rise tomorrow or that our brakes will work the next time we try to stop our car; nevertheless, we believe these things because we have ample reason to do so. We do not need to be omniscient or omnipresent to hold such beliefs, and the same can be true for the belief that no god exists.

Third, it is not true that it is impossible to prove a universal negative. Certainly there are some universal negatives which cannot be proven absolutely and so can only be held based upon the weight of omniscience — for example, the claim “No swans are orange.” We would have to know the contents of the entire universe in order to make such an assertion with certainty.

However, such knowledge is not necessary in order to make other negative statements. Examples of this latter type include “no married bachelors exist” or “no round squares exist.” We can prove each of them with logic, primarily based upon the definitions of the terms involved. To assert the opposite of either statement entails asserting something which is incoherent — and we are rationally justified in denying something incoherent. If an atheist believes that the statement “God exists” is similarly incoherent, then that atheist can say “no god exists” with certainty and without being ominscient.

Thus, we can see that it is simply not true that an atheist need to be omniscient or omnipresent either to hold to reasonable atheism or even to assert the nonexistence of gods. What’s curious is that this myth is addressed on many atheism web sites; thus, if someone makes the claim without an explanation that indicates knowledge of the rebuttals, it’s clear that they haven’t done the slightest bit of research on the matter. They probably just heard it somewhere from a Christian apologist and are repeating it because it sounds good rather than because they found it rational and defensible.

Most, if not all, of these arguments are clearly not consistent with Objectivist principles. So we now have two questions:

First, what is fundamentally wrong with the argument from omniscience from an Objectivist perspective?

Second, what is wrong with the various replies to the argument from omniscience from an Objectivist perspective?

To give my own opinion on the first question very briefly, the argument from omniscience illegitimately attempts to shift the burden of proof from the theist to the atheist. The theist asserts that God exists — and so he is responsible for offering genuine evidence for that assertion. If he doesn’t do that, then his assertions can be justly dismissed as without rational foundation, as mere expressions of faith, as wholly arbitrary. Yet in this argument, the theist offers no positive argument for the existence of God whatsoever, but rather merely insists that the atheist search every corner of the universe to prove that God does not exist. In fact, the atheist should remain comfortably seated in his easy chair, waiting for some rational (i.e. based in facts and logic, not already refuted) argument for the existence of God.