Consider a revealed religion, say Christianity. I will use "the Sources" for the locus or loci where revelation is believed to be discursively embodied. In the case of Catholic Christianity, the Sources are Scripture and Tradition, in the case of Protestant Christianity, the Sources might be just Scripture, and in the case of Islam, the Sources will be the Qur'an and various traditions. The liberal theologian does not believe that any part of the Sources is infallible in matters of faith or morals. I will take this to be part of the definition of a liberal theologian, and will argue that liberal theology is untenable.
As an adherent of a revealed religion, the liberal theologian has to accord some authority to the Sources. And so she has to decide when to follow the Sources and when not to. Since no part of the Sources is taken by her to be infallible, she has to make that decision by the light of her reason.
Thus we get our first conclusion: The liberal theologian, to be consistent, must have a high view of reason. I suspect that some liberal theologians, in the thrall of postmodern thought, do not have a high view of reason. But then they are inconsistent. For there to be any hope of a liberal theology, reason has to be capable of trumping the Sources.
Let us, then, suppose that our liberal theologian has a high view of reason. She rejects claims from the Sources when she takes them to conflict with reason. But what does it mean to conflict with reason? There are two kinds of deliverances of reason: (1) apodeictic ones are justified by a logically impeccable argument from self-evidently true premises, and (2) plausibilistic fall short of that, either by employing inductive or probabilistic argumentation, or by relying on premises that are not self-evidently true. Now I am not planning to offer any argument against in this post against being a liberal theologian in whose theological practice only the apodeictic deliverances of reason trump the Sources. But I just don't think there are any liberal theologians like that. The typical disagreements with the Sources rely on plausibilistic arguments. There are, for instance, no available apodeictic arguments for claims like:
- salvation apart from Christ is possible
- any non-reproductive role that a man can appropriately play, a woman can appropriately play as well
- same-sex sexual relations are permissible
- marital contraception is permissible
- miracles do not happen
- we are the product of a random, unguided, natural process
- everyone achieves salvation
- all the major religions tell us the same truth about God
So our liberal theologian now not only has a high view of reason, but also believes that some merely plausibilistic arguments trump the Sources. But now we have a problem. Merely plausibilistic arguments can be wrong, no matter how strong they are. That is what distinguishes them from apodeictic ones. Now, if the Sources have some authority, it cannot be that every merely plausibilistic argument trumps the Sources.[note 1]
Thus, we get our second conclusion: The liberal theologian needs to distinguish between those plausibilistic arguments that are strong enough to trump the Sources and those that are not strong enough. (The degree of strength required may depend on which part of the Sources is contradicted by the argument.)
From this it follows: The liberal theologian's methodology closes the door to the possibility that we be corrected by divine revelation when there is a sufficiently strong plausibilistic argument for a false conclusion. After all, no matter how great a degree of strength we require in a plausibilistic argument, an argument could have that strength and still lead to a false conclusion. That is because it is plausibilistic and not apodeictic. And if the argument is strong enough, it will trump anything in the Sources. This is an unfortunate conclusion, and one that should worry the liberal theologian, given the possibility of very strong plausibilistic arguments for false conclusions.
On the other hand, revelation often concerns things beyond our experience and beyond the powers of our reason. If one takes somewhat seriously the authority of the Sources and the fallibility of reason, one will be very cautious about the idea of reason trumping the Sources. Thus: The liberal theologian needs to accept that the Sources trump reason in many of the areas of revelation, because these areas go beyond reason's competence. Thus a liberal theologian with a realistic view of reason's limitations cannot be too liberal. And, in fact, I think a realistic view of reason's limitations in regard to plausibilistic arguments makes the project of liberal theology implausible.
Let me end with what I think is one of the most serious in-practice objections to certain moral aspects of liberal theology. Many of the plausibilistic arguments in the liberal theologian's repertoire at most establish a presumption in favor of the conclusion, and thus have the form: "In light of such-and-such facts, there is a presumption in favor of claim p, absent considerations to the contrary." But surely arguments of that form should not trump the Sources--the Sources, after all, are a consideration to the contrary. Let me explain what I mean here by way of example, using an idea from this old post of mine. Take, for instance, a liberal Christian theologian who wants to argue that some form of sexual activity (e.g., same-sex sexual relations) that the Sources say is wrong is in fact acceptable. But in fact there really aren't any very strong positive arguments for the permissibility of a form of sexual activity apart from a presumption of permission, i.e., a view that if we can't find an argument against A, then we should assume A to be permissible. Granted, there might be some arguments based on considerations of autonomy, but Christians who believe that God is in charge of us--and it is hard not to believe that even if one is a liberal theologian--are surely going to be suspicious of that. Nor are there any very strong positive arguments against the claim that God in his omniscience might see some bad consequences of an activity that we do not see--this happens quite often. The most reason can say in favor of the form of activity is something like: "As far as we can tell by reason, there are no strong considerations to the contrary." Yes, but a judgment like that will certainly be trumped by the Sources, unless one has such a low view of the Sources that one is not really considering them to be Sources anymore.
This post is inspired by discussions with Trent Dougherty, but he should not be thought of as endorsing anything here.