Is Omniscience Compatible With Immutability?

It has been held by some that the idea of a being having both attributes of omniscience and immutability is incoherent and that these two attributes are incompatible. This in fact is not the case and it shall henceforth be shown not only that the two attributes are compatible, but where the standard argument for their incompatibility goes wrong.

The standard argument for their incompatibility is set out clearly and concisely in the article by Norman Kretzmann entitled "Omniscience and Immutability" (reprinted in "Philosophy of Religion, selected readings," edited by W. Rowe and W. Wainwright). The argument, adapted slightly, goes thus:

1. An immutable being is not subject to change (by definition)
2. An omniscience being knows everything (by definition)
3. A being that knows everything always knows what time it is
4. A being that always knows what time it is is subject to change
5. A being that is not subject to change does not always know what time it is (contrapositive of point 4)
6. A being that is not subject to change is not omniscient (it does not always know what time it is)
7. An immutable being is not omniscient.

The obvious point of difficulty with this line of reasoning is premise 4. Kretzmann justifies it with an argument something like:

The problem with the above justification lies in the last step. To say that a being has changed simply because it knows something different from that which it used to know is a very strong claim indeed. Surely a change in defining properties or essential properties is required before one can say that a being (or object) has changed. It may be the case that a change in knowledge does effect a change in either the defining properties or the essential properties, but it is difficult to see how a change in the knowledge as to what time it is could cause such a change in these properties. Clearly there is sufficient doubt on this point to ask for considerably more justification and support for premise (4) before it can be accepted.

So this argument for incompatibility is rather shaky. This, of course, does not imply that the two attributes are compatible, merely that they haven't been shown to be otherwise.

Consider then an omniscient being who is outside of time. To such a being our universe would be a four dimensional object. To her, our statement of "it is not t_n" would be like a dot man on a ruler saying "I am at the x cm mark". For us to say "it is now 4:02:39 am on 22/10/1981" would simply be specifying a three dimensional "slice" through this four dimensional object that is our universe. For this being, then, it is possible to know that it is now t₁ (to us) and that it is now t₂ (to us) in exactly the same way as we can simultaneously know that one mark on a ruler is 10 cm from the end and that another mark is 20 cm from the end.

Kretzmann considers this line of argument in the section of his article labelled "Objection D" (Objection C is related, but slightly off the mark. In that objection Kretzmann's analogy of the film fails in the most important respect of timelessness) and yet incorrectly concludes that it is unacceptable.

Kretzmann offers two interpretations of transcendence of time, the second of which is relevant to us. However, even in this he does not capture the idea of a being truly existing outside of time. He says:

His failure to grasp the concept of being outside of time is clearly seen in his use of the word 'eternal.' In the above interpretation there still are, to us, infinitely many propositions of the form 'it is now t_n,' each of which is true at some stage; it is simply that propositions of this form are, to the being outside of time, all true at their own particular "slice" of the four dimensional universe and false at all other "slices." This is precisely analogous to the proposition "This point is x cm from the end of the ruler" being true at exactly one point and false at every other on the ruler.

Kretzmann then goes on to claim that this view requires the immutability of everything, and not just the being. This is true in some fashion, but only to the being outside of time. To us, trapped in time, everything does change in the same way as a wedge gets thicker as you move further from its point. When considered as three dimensional objects moving through time it is obvious that things do indeed change, and thus Kretzmann's conclusion of this view of the omniscient being entailing the immutability of the universe does not hold true.

Thus we have an interpretation of omniscience with respect to propositions of the form "it is now t_n" which is compatible with immutability. It is fairly clear that this interpretation allows a being to be both immutable and omniscient, and thus the two are compatible.