Ophelia Benson responded in the comments to my recent post on disgust as a moral emotion. One of my responses to her comments got a bit too long. I recommend you read the comment to which I am responding. To sum it up briefly, we are discussing what role, if any, disgust can have as an initiator; and Benson suggested that it could do so as a source of hypotheses. My comment follows:
I do agree that it can be a source of hypotheses. The problem with this view taken as complete, however, is that it seems to eliminate entirely any serious moral role for disgust. As you note, hypotheses can come from anywhere. But if disgust is nothing but a source of hypotheses, not different from any other source, then there is no moral role to disgust at all; it is abstracted too much from any moral action. It has no more a serious moral role than any other source of hypotheses (e.g., random guessing).
A parallel might help. I see arguments like yours quite a bit from the anti-feminist crowd with regard to anger and indignation as moral emotions. The click of anger and indignation at mistreatment (of oneself or others) is allowed a place as an idea-generator, divorced from the action itself by the medium of general rules -- by creation of hypotheses, more or less, although I don't know of anyone who has put it quite that way -- and this is supposed to contrast with the more visceral place it has occasionally had in feminist consciousness-raising. The problem there, as here, is that it is simply a moral form of Cartesian dualism. A sharper division is made between passions and actions than can be seriously entertained. In fact, any passion is itself a reason for action; the only question is whether it is adequate for it given every other consideration that has to be in play. Reasons for action, after all, are defeasible; to that extent you're quite right that we shouldn't trust disgust alone, because we need to look out for defeating reasons for action. But that allows disgust to have a rather robust role as an initiator, just as anger and indignation can have a rather robust role as an initiator.
When feminists try to show you just how infuriating some aspect of society is, they aren't saying, "We have a hypothesis that this is a bad thing that should be tested." They are saying that, if we aren't ignoring some hidden factor that needs to be brought to the fore, the fury induced is itself consciousness of something wrong. When, for instance, you try to convince people that a particular option is disgusting by describing it a certain way, you aren't saying, "Hey, look here, I have a hypothesis, test it out and get back to me"; rather, the message you are conveying is, "Look, this is the sort of thing that should be shunned or avoided, and I think you can see that directly if you look at it in this light." And this, I think, is often the right sort of message to convey. Of course, it's quite reasonable to bring further reasons, and sometimes it would be unreasonable not to do so; but once you've conveyed that it strikes (at least some) people as disgusting, you've, by the very act of doing so, conveyed a reason for avoiding it, if possible. The qualifications ('if possible'), of course, are necessary; but they presuppose that passions like disgust are reason-giving.
I think the way to handle deviant disgust, as with the inter-racial marriage case, is not to pretend that socio-moral disgust is not a reason to act, but to insist vehemently on all the many and strong countervailing reasons. In other words, when someone exhibits disgust at the idea of interracial marriage the best route is not to deny generally that disgust is a defeasible reason, but to insist on its defeasibility and actual defeat in this sort of case by pointing out opposing and defeating reasons. Some of these defeaters are found in disgust at other relevant things (e.g., at the treatment interracial married couples sometimes get); others in other emotional responses; yet others in reasoning about our moral consistency. To borrow terms from Hume, we handle faulty emotional responses by giving people a more 'general point of view' through the 'intercourse of sentiments'. The fault arises from not having a sufficiently well-rounded perspective on the situation, from focusing too narrowly on certain aspects relevant to their own interests, while ignoring others. So, for instance, bigots zoom in on their emotional response to one particular feature of the situation, overlooking other features, the standpoints of other people, which would serve to moderate, refine, redirect, or completely change their response (depending on what, exactly, they are ignoring).
We can look at it from the other side, too. Suppose one of the spouses in an interracial marriage is confronted with an 'anti-miscegenationist' mouthing off vilely and feels a sharp response of disgust, revulsion, and anger. My suggestion is that those things are themselves, and on their own, reasons to act -- the fact that it inspires these emotions is, and should be, capable of legitimately grounding action. The question is not whether the spouse has reason to act; he or she obviously does, and no further reasoning about that is required, except to the extent the person in question has reason to think his or her emotional responses faulty in general (e.g., a mental health problem). The question is whether there is any reason for self-restraint, and it is this that calls for deliberation and reason. Someone who rejects the anti-miscegenationist's views vehemently on disgust alone is not being unreasonable at all, unless it can be shown that they've been negligent, overlooking or refusing to see some good reason not to act so immediately on their disgust. It would seem rather absurd, already responding to the vileness of the anti-miscegenationist with disgust, anger, and the like, to say to oneself, "OK, these feelings suggest the hypothesis that these vile insinuations and insults are wrong and perhaps worthy of punishment; we can test this out and get a peer review, to make sure, and then proceed to deciding our proper course of action." Of course, we might do this in more leisurely moments when we are engaging in general moral self-maintenance and improvement. But that can't be all of it, because it doesn't do justice to practical reasoning, nor to the role disgust and other emotions are capable of playing as defeasible reasons for action.