The stone

  1. Either x can create a stone x cannot lift or x cannot create a stone x cannot lift. (Premise)
  2. If x can create a stone x cannot lift, then there is a task x cannot perform. (Premise)
  3. If x cannot create a stone x cannot lift, then there is a task x cannot perform. (Premise)
  4. So, there is a task x cannot perform. (By 1-3)
  5. An omnipotent being can perform every task. (Premise)
  6. So, there is no omnipotent being. (By 4 and 5)

 

Wade’s observation

Premise (3) is false, because

(a)    x cannot create a stone x cannot lift

is equivalent to

(b)   x can lift every stone x can create.

And (b) clearly doesn’t imply a limitation.

 

Aquinas’ possible move

Premise (5) is false as there are things an omnipotent being cannot do.

Descartes’ possible move

God can make contradictions true. Thus, (3) is false as God can create a stone he can’t lift—and lift it.

 

Some possible definitions