Daniel Wallace in his widely used, Greek Grammar Beyond the Basics categorises 33 different usages of the Genitive case.This was the textbook used in my 2nd year seminary course for teaching us how to use Greek for exegetical purposes. Today I want to soapbox about some bugbears I have regarding endless classifications of case usages.
When you read some of the material in the debates about πίστις Χριστοῦ, between it being an 'objective genitive' (where Christ is the object of the implied verbal idea, so 'faith in Christ') or a 'subjective genitive' (where Christ is the subject of the implied verbal idea, so 'Christ's faith/fidelity'), one gets the idea that some people think that there was a 'choice' between the two. As if Paul had a drop down menu of genitive case usages, and 'selected' one or the other. This is, obviously, not how language works. The 'option' that Paul could choose from was just 'genitive'. Where there is no morphosyntactic difference, there is no option; Paul's other options were to express the idea by means of other constructions rather than the genitive.
Take that illustration and multiply it out; one error that I find students sometimes making is thinking there is this kind of 'choice' between case usages. There is not. One does not choose between different 'types of genitive' as a speaker, one simply chooses to use a genitive construction. Which means when we, as receivers, come to a text we should not imagine they did have that kind of choice! It distorts our understanding not only of what that construction might mean, but also the importance of that choice.
This also sometimes manifests in a false sense of free choice among learners. The kind of thinking that says, "Okay, here are 33 genitive usages, and here is a genitive, and I would like to understand it according to category 15." We don't have that as a 'choice' either. My current students don't normally come up with this kind of error, because they haven't been exposed to this kind of classification and I don't encourage this kind of labelling (besides the nightmare it would be to translate and explain 33 categories of genitive usage into Mongolian). But I have encountered it elsewhere. The student says, "I think it's usage Y", "Why?", "That's how I take it". Sometimes the choice of usage is wildly inappropriate.
What's the role of labeling? What it isn't is a way of getting the meaning out of the text. That is back to front. Consider participles. They do a real load of work in Greek language. I won't bother counting up the number of usages Wallace categorises. Almost all of these can be figured out by considering, "what is the sense of the words involved". This, for instance, is how to evaluate between concession and causation: does the sense of the two phrases/clauses/ideas fit better with A because B, or A despite B. It is always ad sensum. Labeling is a post-understanding process - once I understand the text, I may put a label on it.
However, and this is perhaps were labeling is useful, the sense of a construction is ambiguous. For example, going back to pistis Christou, that could be an ambiguous construction. I would argue that we need to recognise two types of ambiguity, sender-side and receiver-side.
Receiver-side ambiguity occurs when we are inadequately able to make out the meaning of the text. This may be due to inadequate language acquisition, on a broader scale we may simply have an inadequate corpus to allow us to work out some ambiguities at all. It presumes that the author didn't perceive the message to be ambiguous, but we do.
This happens to me all the time, when people say, "What have you been doing?"; lacking a temporal reference, I always find the statement ambiguous. Now I take to clarifiying, "Do you mean right now, or today, or in the last six months?" Sometimes the context of the conversation has clarified this. But other times not. Clearly the speaker considers it unambiguous; the ambiguity is receiver side. When we deal with written texts, disambiguation cannot be achieved through dialogue.
Some ambiguity is sender-side; the sender has failed to communicate in a way that is clear, either intentionally or unintentionally. If it is unintentional, we might consider it a fault of the speaker; if it is intentional, we may conclude that the speaker deliberately wants to 'keep options open' for interpretation.
To come back to pistis Christou as my example, I do not believe this is
sender-side ambiguity at all. If Paul wanted to express a subjective genitive idea, I believe he would have rendered the whole phrase differently, avoiding the genitive construction. It is one reason I find the evidence on this question from patristic authors compelling - native speakers of Hellenistic Greek did not consider Paul's construction ambiguous, so much so that they don't even discuss the objective vs. subjective idea. That tells me that there was no ambiguity for them, that the ambiguity exists primarily from moderns, as a receiver-side ambiguity created by inadequate thinking about case usage and/or inadequate Greek acquisition.
My point in all this is not to focus on pistis Christou, but on the practice of labelling categories. Is it useful? Yes, but labeling should follow understanding, not be used as a tool for understanding. If you don't understand the Greek text, you will not be able to label either well or fruitfully.