Norman Malcolm has a paper offering an analysis of the way we ordinarily use the phrase "I know". Malcolm observes from cases that we often use the phrase "I know" and "I believe" to refer to the same belief/knowledge situation when all of the objective factors are the same. For example if I say that I know that there are cookies in the cookie jar (because I just got back from the cookie jar and saw that there were plenty of cookies there) and you go and look and see the cookies, I would say that I knew it. But if you went and looked and saw that the jar was empty you would say, "No, you only believed it".
Accordingly, our use of the phrase "I know" is inconsistent with any traditional account of epistemology. According to Plato, when a boy understands the proof for a theorem in geometry, such as that given any square another square whose side is the length of the diagonal of the original square will be twice area of the original square, he not only knows it, he knows that he knows it -- that is he can introspectively inspect the proof in his own mind and see that the conclusion must be true. This opposed to the person who excepts the same claim on the authority of Euclid. Such a person might be willing to say that he knows that the claim is true but also be willing to consider it false if he discovered that many other geometricians disagreed. But the person who actually possesses in their mind the proof would think that such rival geometers must somehow be mistaken.
In other words, we say "I know" in different ways. Specifically, there is a strong use and a weak use of "I know". If I say "I know" in the strong way, what I mean is that I am not open to any counter evidence to what I am claiming. If I say "I know" in the weak way, what I mean is that I am open to any counter evidence to what I am claiming. The two uses are logically exclusive of each other. In other words, my use of "I know" tracks with what I am prepared to do.
Malcolm observes that this distinction between the strong and the weak use of "i know" cuts across the traditional distinction between a priori and a posteriori knowledge. Their are certain mathematical claims that we would not hesitate to say we know (like 2 + 2 = 4) and think that anyone who doubted it was dysfunctional. But many others (like e^--(pi x i) = 1) which we would be willing to admit a need to recheck our work to be sure we are right). Also while "the sun is 9 x 10^7 miles away" and even "there is a heart in my chest" are things that I could imagine some measure of countering evidence for, according to Malcolm, I could not imagine any possible evidence that would refute "here is a computer" for me. He further argues that for me I could not have an infinite chain of weakly used knowledge claims for any a posteriori claim, so that there must be a posteriori strong knowledge claims somewhere for me.
So traditional epistemology is completely orthogonal the way I use the claim to know and its logical characteristics. Further, even though its true that for some subject S and some proposition p, if S knows that p, then it is true that p, it does not follow that if I claim I know that p that I either know that p or that p is true, for either the strong or the weak use of knowing. So the description of how we use "I know" teaches us nothing about epistemology and whatever is true about epistemology does not effect our use of "I know". Consequently, traditional epistemology is otiose to ordinary language.
But even if Plato is wrong and there is no way of distinguishing knowledge from mere belief by introspection, introspection does distinguish between my use of "I know" strongly or weakly. Once I am aware of the distinction, I can discern and choose which use to make of "I know" and so such uses are conspicuous to me because I control them.
I think such an account has interesting consequences for faith and reason. One of them is on the evidence for the resurrection of Jesus. Consider the case of doubting Thomas. He continues to doubt even the authority of his friends' testimony until he sees Jesus alive for himself. We could imagine Thomas saying "I know that no one ever comes back from the dead" but his consideration of criterion for a genuine appearance of Jesus (feeling the nail and spear prints) suggests that this was "I know" in the weak sense. However, seeing Jesus face to face would have been a paradigm case of what Malcolm calls the strong a posteriori use of "I know" -- "I know Jesus is here". In other words, for Thomas:
(1) I knew (in the weak use) that no one comes back from the dead.
(2) I now know (in the strong use) that Jesus is alive.
are consistent. Whatever might be odd about the claim that someone rose from the dead, there is nothing logically odd about it.
Another use for this discussion is in determining the import of doctrinal subscription. Basil Mitchell uses the example of the French Resistance Leader to illustrate how faith is rational without being specific about what would make it false. He argues that we can meaningfully talk of falsification without specifying before hand what counts as a falsifying instance. Suppose you are in the French Resistance in WWII. In a foxhole you meet a charismatic figure that inspires trust and confidence who claims to be the secret leader of the Resistance. But later you see him leading the Nazis in squashing Resistance fighters. Others may give up on him but your original encounter with encourages you to think that perhaps he is tricking the Nazis to let down their guard. There may be some situation that would really compel you to lose faith in the leader but for now you cannot think of what it would be like. It does not mean that you believe in the Leader no matter what. We can imagine the resistance fighter even saying in this situation that he knows (in a weak use of knowledge) the Leader is fighting for us.
According to CS Lewis, though, there are situations in which we would be reasonable to say that we could not seriously entertain any possibility of doubt in someone. If we are on a ledge on the 100th story of a burning building and the fireman on the rope in front of us is telling us to step off the ledge, even though his direction seems to us to be the height of absurdity, we must not regard that absurdity seriously. In such a situation we could imagine steeling ourselves to action be saying "I know (in the strong use) that I can safely step off the ledge". According to Lewis before we can reasonably say this we must have some evidence for it independently of the situation, but in certain situations obstinacy of belief is appropriate.
Consider these claims:
(3) I know that what God tells me is true.
(4) I know that God is speaking to me here in the Bible.
(5) I know that infralapsarianism is true.
It seems that (3) is an example of a strong a priori use of "I know". Once we know what "God" and "speaks" mean, we can see that its true and in a way that makes it impossible to expect counter evidence. Further, it seems that (4) is an example of a strong a posteriori use of "I know". You might not think so but it seems to me that one could either have an immediate impression of God speaking in the Scriptures (say) in the sense that Malcolm speaks of a strong knowledge claim like "here is a computer", or start by having an encounter with the text that is similar to Mitchell's account of the Resistance Leader but which existential urgency may lead you to strengthen along the lines of CS Lewis' account of belief. In such cases, it seems that (4) is appropriate. But in the case of (5), (note: infralapsarianism is the doctrine that God's decree that there would be a fall of all mankind is logically prior to His decree that some should be elected to salvation) the state of affairs that is the basis of (3) and (4) together leads (if it indeed does) to the acceptance of (5) but it seems that one should only affirm (5) in the weak way rather than the strong way because we may admit the possibility that we may have incorrectly read the text or made a false inference from the textual data. However, Malcolm's account helps us make sense of how it is that we can speak so confidently even in differing conditions of belief formation. I say "I know" in both cases and the logic of saying I know allows this. Further, I could even be aware that saying "I know" in (3) - (5) does not imply that I know or that what I claim to know is true, and yet this would not prevent me from saying (3) - (5) nor would it keep me from being in my rights to say (3) - (5).
Now one way to characterize doctrinal assent is that such an assent is determined by what I am prepared to do and what I am prepared to do can help specify whether I am giving my assent in the intended way or not. Many humanists say that there is no greater bane to thought than holding to doctrines. However, if my holding to a doctrine that p means that I am prepared to say "I know that p" as Malcolm has discussed this, it is difficult to see how that could be a bane to thought. I know (strongly) that doctrine is not a bane to thought.
Further, if someone wants to know if I subscribe to a doctrine and I say "Yes, I know that the doctrine is true", that person can ask whether I am using "I know" strongly or weakly. I say that I can only say that I know that doctrine is true in a weak use, not a strong use. To which the reply might be, "Sorry, but we can only grant membership to those who would say that they know that doctrine is true in a strong way". The difference between the strong and the weak use distinguishes different requirements for assent in the same list of doctrines. Another possibility is that it may not matter which, one must at least claim knowledge in a weak sense.
So when we ask what is intended by the requirement a necessary condition for being a pastor in a Presbyterian denomination is that one subscribes to the Westminster Confession of Faith, we can ask if that means that pastor candidates must be able and willing to say that they know in a strong way that the contents are true. If we allow the caveat that if at any time the pastor changes their mind about any doctrine, they will notify the denominational authorities for evaluation and possible administrative dismissal, then if that means we are asking the candidate to take seriously the possibility he might be wrong, then we are requiring that the doctrinal acceptance implies a weak use of knowledge, but if we take the caveat to be essentially trivial then we are requiring that the doctrinal acceptance implies a strong use of knowledge. Either way, not all candidates who do hold to the doctrine would be acceptable. Of course, this is a false dilemma because it may be that the caveat takes it to be a possible situation even for those who do hold to the doctrine and claim knowledge of it in the strong way and this because the caveat is aware that even knowledge in the strong sense does not imply truth so that even the one who cannot imagine counter evidence my find the unimaginable thrust upon him. The caveat implies that not all doctrinal departures are within the scope of moral irresponsibility, sometimes a responsible person may have to disagree so its not clear that every doctrinal departure is a failure of character even though that is certainly possible and likely. Also, allowing weak uses of knowledge allows that some of doctrines to be accepted just on the authority of a credible tradition which means that one may accept the standards even if one has not personally worked out every article of them. Finally, since if Malcolm is right that there must be some cases of the strong use of "I know" if there are to be any cases of a weak use of "I know" and since some of those cases may turn out to be doctrines as well like (3) and (4), then the best sense of the caveat seems to be that while one must be prepared to say of any doctrine in the set that "I know", the caveat is indifferent about whether that "I know" is strong or weak.
All that to say that some interpretations of subscription, such as that all the doctrine must all be accepted as known in a strong way and never in a weak way, may be abuses of subscription requirements. On the other hand, to say that what one really is required to accept the system of doctrine in the confessions and not every jot and tittle of it suggests that some of the doctrines are different from the rest and whether or not this difference consists in what certain doctrines must be held strongly whether the rest are held strongly or weakly. But since the system of doctrine whatever it is is distinguished from the evangelical essentials there is a further question about the differences among the privileged system of doctrine. However, this may be a case not of distinguishing between what is strongly held from what is weakly held but between what must be strongly held in order to be accepted as a church member and what must be strongly held in order to be a pastor which would include the former. It also seem that another abuse of subscription would be if the real doctrinal requirements for pastors differed exclusively from those required of members including in the respect of whether they were held strongly or weakly.
Finally, Malcolm's approach sheds some light on how such communities that define themselves doctrinally can be legitimately exclusive. If doctrinal subscription is in part about what we are prepared to say it seems that prima facie it may be related to what we are prepared to do and in the existential sense what we are prepared to be. If a community is devoted to a certain vocation, it may require the right attitude to the presuppositions of that vocation and that attitude may require being prepared to say certain things. And in perpetuation, we may be required to teach what we say we know so anyone who is not in sync with this is an impedance to it. There is a doctrinal aspect to asking a person to either lead, follow, or get out of the way.