Responses 006 (May 2013)
It might seem obvious, but the question is not "Can we trust our emotions... ?" but "Can we know when to trust... ?" This is not as easy as it seems.
On one level, the "Can we know... ?" kind of question is somewhat facetiously answered all the time, by people who should know better, with "No, of course not, how can anyone know that they know anything?" On a slightly higher level, the point of asking a 'can I know' question is so that one can argue whether or not one has a reasonable chance of knowing something — it's not a 'will I know' question either.
To extend the idea further, let's ask this: "Can we know when to trust X in the case of Y?" It's a question about the reliability or validity of the approach, and there are two main ways of trying to answer it.
The first is inductive, a historical-legal approach based on the evidence of precedents and antecedents. Supposing that trusting X has always led to success or truth or knowledge in the case of Y. Then clearly we can know when to trust X — it's whenever Y is the case. But the problem of the inductive approach is that at any time, a 'black swan' might appear — a fluke that happens and shows that prior performance is no guarantee of future success. How much can you trust something based on its history? Does the 100% reliability of the past continue into the future?
The second is deductive, a philosophical-logical approach based on reasoning. If Y is such that Y is susceptible to success when using X, then we can always trust X based on the nature of Y. Then we clearly can also know when to trust X — it's whenever Y (or something with the X-related properties of Y) occurs. However, the problem of the deductive approach is that it depends on our first assumption or axiom being true. If we think Y is such, but it isn't, then all our subsequent reasoning is flawed. How much can you trust something based on logical conclusions that are worked out based on an assertion that might not be valid?
Now let's consider 'pursuit of knowledge... history and one other AOK'.
History can be defined as the construction of a narrative based on verifiable events in generally chronological order, so as to explain the present in the light of the past. History should make no attempt to predict the future; it is a sense-making exercise based on things that have already happened and are far enough away that we can begin to gather a fairly comprehensive collection of evidence concerning those things. (You can probably find useful definitions of other AOKs elsewhere in this blog.)
So how would we know when to trust our emotions when in the pursuit of historical knowledge? Clearly, the evidence must be verified by sense and reason to a large extent. But the pursuit of historical knowledge consists of different types of evidence: witnesses and reports, archaeological finds, ideas from the other human sciences (sociology, anthropology etc) about how humans normally behave.
Some of those kinds of evidence require us as humans to respond as humans — to try to understand by empathy and emotion why people did things. This is what emotion as a way of knowing is all about — it is the body's complex physiological and biochemical response to incoming material, giving us a sense of how other humans might feel about it and thus altering or forming our psychological perspective on it. We then interpret what we see in the light of what we feel. In this way, the history we then construct therefore makes more sense to our readers and may be closer to a true explanation of why humans did something. How do we decide WHEN to trust emotion in this way? If we can decide at all, that's the answer to part of the original question.
And that's the beginning of the argument you need to construct. Enjoy!