God and the Heavy Rock He Can Lift

I'm currently teaching a course on systematic theology to some high school students.  We've been discussing God's omnipotence and today we looked at the old paradox, "Can God make a rock so heavy he cannot lift it?"  As we looked at this I tried to stress that this is not some theoretical issue they will have to think about.  I told of how back in 2002 while working at a big-box store I got into a series of written exchanges about philosophy and theology with one of the young men who collected carts out in front of the store.  We had a fascinating and free-ranging discussion that was both cordial and stimulating.  I shared with my class this exchange that B-. and I had to demonstrate the real world application of what we were discussing in class.

B-. wrote:

If god is infinite and the ultimate creator, then lets say that for some reason he decides to create a boulder so heavy that he can’t lift it.  Assuming that he can do so, cause he can do anything.  This would then have a problem, the rock now surpass[es] “god” as being something greater, if only for a moment.  Now the rock is to be worshipped and made sacrifice for as being your supreme being.

I responded with this comment:

The “God and the rock so heavy He can’t lift it” is a familiar objection—familiar but fallacious.  Your argument contains a premise which is false thus invalidating your argument.  The false premise is that there is such a thing as a boulder which God cannot lift.  All that God creates is under His sovereign control therefore there is no such possibility of a rock which God cannot lift.  God cannot create a rock so heavy He cannot lift it.  Does this compromise God’s omnipotence (God’s all-powerfulness)?  Not at all.  Christian philosophers have always defined and understood God’s omnipotence to exclude that which is contrary to God’s character.  For example, can God “kill” Himself and cease to exist—no.  But this limitation on the definition of omnipotence is a necessary consequence of God’s perfection.  God is perfect in His existence—He cannot “die.”  He is perfect in strength—He can lift anything that is “creatable.”  It is no limit on God’s perfection that He cannot be imperfect.

Of course, more could have been said but I wrote this on a lunch break!  For those looking for a good introduction to this topic I would recommend Ronald Nash's discussion in his small book The Concept of God (Zondervan, 1983), chapter 3--especially pages 47-49.