This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.
I have recently been studying Frank Jackson's Knowledge Argument. As you know, it suggests that there is a kind of knowledge that is a posteriori -- an experiential knowledge that cannot be had until the relevant experience is had. This kind of knowledge is usually described as a "what it is like" kind of knowledge. As Locke points out, I can only know what the taste of pineapple is like when I have actually tasted pineapple. I tend to agree with this intuition concerning knowledge. But, it raises a few questions for me regarding God's omniscience: 1. If God is omniscient (and I believe He is), how do we account for His having this kind of a posteriori knowledge? Should we conclude that God could have this knowledge without experience because of His infinite cognitive abilities as compared to our finite abilities? 2. Does the statement of the Hebrews penman in Hebrews 5:8: "Although he was a Son, he learned obedience through what he suffered;" have any bearing on this question? Does this verse teach that Jesus, though God, gained experiential knowledge by taking human form? If so, would this imply that God lacked this kind of knowledge prior to Jesus' becoming flesh? 3. Does God know what it is like for a sinner to revel in sin or to desire to sin? Could He know that feeling without feeling that feeling? 4. Could God have been justified in creating man if He did not first have this "what it is like" (intentional) knowledge? Thank you for your work. It has been a tremendous help to my faith!
Dr. William Lane Craig’s Response
These are difficult questions, Nathan, which we discuss in my class on divine omniscience.
Divine omniscience is defined in terms of propositional knowledge, e.g., for any proposition p, if p, then God knows that p and does not believe not-p. Such a definition is meant to capture the intuitive idea that God knows all truths and believes no falsehoods. This kind of knowledge is knowledge “that ____.”
By contrast the kind of knowledge you are talking about (what it is like) is non-propositional knowledge. It is not true or false. For example, knowing how a pineapple tastes is not true or false and so is non-propositional. There is something to be known here, but it is not a truth.
Omniscience, being defined in terms of propositional knowledge, does not require God to have non-propositional knowledge. He must know all truths about how a pineapple tastes, e.g., that a pineapple tastes tart, that a pineapple tastes refreshing, etc., but He needn’t have non-propositional knowledge of how a pineapple tastes.
It once seemed to me that God does not have the sort of non-propositional knowledge you describe because He lacks the requisite experiences. But then I got to thinking about a remark by David Lewis that there must be some sort of mental state that someone who is experiencing the taste of a watermelon is in. You could be in such a mental state without actually eating the watermelon. So why, it occurred to me, couldn’t God put Himself into such a mental state so as to know how a watermelon tastes? It seems to me that this is clearly possible. In that case God could have non-propositional knowledge of tastes, colors, feels, sounds, etc., in addition to His propositional knowledge of such things. God’s greatness is thereby exalted, for it turns out that God’s cognitive excellence is even greater than omniscience!
So in answer to your questions:
1. “If God is omniscient, how do we account for His having this kind of a posteriori knowledge?” God’s non-propositional knowledge is not a function of His omniscience. His omniscience gives Him all propositional knowledge. If He has as well non-propositional knowledge such as you describe, it will be a function of His ability to assume the same mental state as someone having such an experience. Does God have “this knowledge without experience”? Yes and no; He can have the experience of tasting a pineapple but without actually eating a pineapple or having taste buds. Is this because of “His infinite cognitive abilities as compared to our finite abilities?” No, we can imagine a neuroscientist’s stimulating a person’s brain such that the person is put into a mental state of tasting a pineapple. God could do this Himself at will. Of course, to have the unlimited range of non-propositional knowledge you’re thinking of, God’s cognitive abilities must be infinite.
2. “Does the statement in Hebrews 5:8: "Although he was a Son, he learned obedience through what he suffered;" have any bearing on this question?” No, because in this case we’re talking about knowledge which the incarnate Son had in his human nature. Jesus obviously knew, e.g., what roast lamb tastes like. But I’m suggesting that such non-propositional knowledge may not be limited to the Son. Moreover, “learning obedience” isn’t a matter of acquiring non-propositional knowledge; it’s an idiom for the moral sanctification of his human nature.
3. “Does God know what it is like for a sinner to revel in sin or to desire to sin? Could He know that feeling without feeling that feeling?” As explained, I once doubted that God has this sort of non-propositional knowledge, since it is impossible for Him to sin. He could know every truth about how sinners feel, but He would not know how it feels to revel in sin. But now I’m inclined to think that God could have such non-propositional knowledge. For there is surely a mental state had by someone reveling in sin, and by putting Himself in that mental state God could know just how such a person feels. God would not Himself revel in sin or desire sin, but He would know how someone who does feels.
4. “Could God have been justified in creating man if He did not first have this ‘what it is like’ knowledge?” Well, why not? Why wouldn’t propositional knowledge be enough, in particular, knowledge of all true counterfactual propositions concerning creaturely free choices (middle knowledge)?