I was thinking about the topic of emotions, and their reliability in different areas of study(science, history, math etc.). The question I have is: Can we know when our emotions are credible in the pursuit of knowledge? For example, pseudoscience is caused when emotions trump rational thinking; so, is there ever a time when we can be sure our emotions are not deceiving us in the pursuit of knowledge?
Your question spans virtually the entire history of philosophy (not to mention that it's difficult to see exactly what you're asking). But I'll try to briefly shed some light. Your question also posits that rationality and emotionality are at opposite ends of the spectrum, but I think that may be a false dichotomy (unless you can prove otherwise, of course).
For Aristotle, for example, emotions (pathe, plural of pathos) were largely non-active. Thus, I don't think he would say that emotions were conducive to any sort of epistemic goal. In the Poetics, catharsis (the release of emotion) tends to generally have ambiguous connotations but, again, we don't see any epistemic implication. There seems to be a ton of information on ancient and medieval works about emotion here.
If you read Rousseau, however, he does seem to sometimes argue that traumatizing emotions he felt as a child fueled his quest for the 'virtues' (take that as you will - Confessions is not meant to be read as a purely philosophical text). Emile, which is a more epistemologically-oriented work, does not seem to make the same point. In it, he accepts Locke's tabula rasa (knowledge is mostly a posteriori and obtained empirically, etc.). Hume (in Four Dissertations) argues that catharsis is purely aesthetic (no epistemic implication). However, Hume did lay the groundwork for the emotivism of the 20th century. Emotivism is an ethical theory though, not an epistemic one - so still no dice.
Descartes, as always, comes up with his own crazy ideas (which I find fascinating). From SEP:
Perhaps the most distinctive of the passions that Descartes identifies, however is the one that involves no evaluation of its object: wonder [admiration] merely presents its object as something novel or unusual. As such, wonder produces no change in the heart or the blood, which would prepare the body for movement. But it does involve the motions of the animal spirits through the brain and into the muscles, thereby fixing an “impression” of the object in the brain. And that explains the function of wonder: to “learn and retain in our memory things of which we were previously ignorant” (AT XI 384, CSM I 354). It is our response to those features of the world worthy of our consideration – something useful both for the preservation of the mind-body union and for the soul itself in its pursuit of knowledge. Descartes's understanding of wonder may well recall Aristotle's famous dictum that philosophy begins with wonder. But wherever it begins, Descartes certainly does not think it should end there. Wonder can become excessive, and make us crave novelty simply for its own sake. Wonder is only functional if it prompts us to resolve it in the satisfaction of knowledge.
So here is where we find something of interest. Descartes argues that 'wonder' (curiosity) is one of the primary passions (emotions). He goes further by arguing that wonder is, in fact, conducive to an epistemic goal. But (like Rousseau) concedes that too much emotion is never a good thing - even if it's curiosity. After all, that's what killed the cat.
The principle elements, or timbers, of the Modern Framework divide into two groups, reflecting this initial division of Nature from Humanity. We may formulate the dozen or so basic doctrines, and discuss them here in turn. [...] On the Humanity side, we find half-a-dozen similar beliefs:
• The "human" thing about humanity is its capacity for rational thought or action.
• Rationality and causality follow different rules;
• Since thought and action do not take place causally, actions cannot be explained by any causal science of psychology;
• Human beings can establish stable systems in society, like the physical systems in nature;
• So, humans have mixed lives, part rational and part causal: as creatures of Reason, their lives are intellectual or spiritual, as creatures of Emotion, they are bodily or carnal;
• Emotion typically frustrates and distorts the work of Reason; so the human reason is to be trusted and encouraged, while the emotions are to be distrusted and restrained. (109–110)
When emotion is entirely left out of the reasoning picture, as happens in certain neurological conditions, reason turns out to be even more flawed than when emotion plays bad tricks on our decisions. (xii)
Damásio is a neuroscientist/neurobiologist who discovered that certain brain lesions would cause two simultaneous effects:
- inability of patients to access emotions
- inability of patients to employ practical reason
Practical reason is the ability to form long-term goals and then successfully achieve them. So, it would seem that we aren't reliable when we are without our emotions! Furthermore, the animus toward emotion which I have identified and documented has very likely actively thwarted research into your precise questions. Now, given that Descartes' Error has so many citations and is now twenty years old, hopefully there is more and more research on your question. Indeed, looking at the citations may guide you to good work. For example, I found Rosalind Picard's 2000 Affective Computing (5500 'citations', Wikipedia article):
The latest scientific findings indicate that emotions play an essential role in rational decision making, perception, learning, and a variety of other cognitive functions. Emotions are not limited to art, entertainment, and social interaction; they influence the very mechanisms of rational thinking. We all know from experience that too much emotion can impair decision making, but the new scientific evidence is that too little emotion can impair decision making. (x)
It would seem that if you want to see how emotions can be reliable and useful, this might be a good book with which to start!
You have misidentified the cause of pseudoscience, it is not emotional thinking, people generally believe things based on their direct perception, the emotions come later.
The pseudoscience is usually due to the genuine altered perception of people, altered by individual differences in wiring or by hypnosis, meditation, brain damage, psychoactive drugs, as well as training in perception by studying the arts. The persistent recurring topics of pseudscience almost always have a basis in a definite perceptual phenomenon, that you should try to experience, try to isolate and study in people, because it isn't bunk:
- ESP: this is synchronicity plus the back-dating perception, where someone will tell you something, and you feel that you already knew what they said before they said it. There is also the effect of nonverbal cueing, and various social signals that are barely perceptible. The synchronicity of thoughts is real and easy to demonstrate statistically, especially among people who know each other well or who share a common literature background, and so can predict each other's thoughts. These phenomena are not supernatural, but the perception of ESP is stronger in people who are sensitive to these things, and they want science to validate their perception, not their emotion. It's not going to do that more than I just did above.
- Auras/Orgone energy: The "energy field" of people is something people actually percieve, as a vague glow surrounding a person, something like an after-image, in a color that James Joyce called "heliotrope". It's there to percieve, you can see it, it's just not made of matter and the only instrument that can detect this afterglow is the human brain. It is perceived relatively stably by people trained in visual arts, or who are socially sensitive, or who are high, and these people see something there, so they want a machine that will detect this. That's hopeless, because it is purely perceptual, but that doesn't stop people from making orgone machines. The halos of religious iconography are representations of this.
- Conspiracy theories: This is the perception of collective agency in the world--- an intelligence due to a collective making a decision that is not due to any one person, and fallaciously concluding that since all intentional action must be due to individual people, or to groups of people in collusion, that the collective coherent effects are due to a conspiracy in a small room. There are a handful of actual small-room conspiracies, but most of the truly vast conspiracy theories emerge from misattributing the thoughts of the gods to one person or to groups of people actively holding these thoughts. There was no "DMV conspiracy" to make the experience at the DMV miserable, likewise there is no "beaurocrat's conspiracy" to make paperwork onerous, although you wouldn't know it based on the results.
- UFO/hollow-earth: This is due to actual hallucinations people have, drugs speed this along, and also some rare physical phenomena like ball lightning. The idea that there are other intelligent agents in the world other than people is completely reasonable to a lot of people, considering the collective agency of the gods, and people see gods everywhere, and those who don't call them gods end up calling them something else.
Other things called pseudoscience, like perpetual motion with magnets, are just bad or discredited science, not pseudoscience. This includes most pseudoscience topics. Other pseudoscience, like radiation hormesis or cold fusion is just open questions, and there pseudoscience is used as a poltical label to clobber people working on something unpopular.
The emotions that come with ideas are usually posterior, in that one makes up one's mind early, and later, one has an emotional reaction to something that disagrees with what you believe because you already decided you didn't like it a long time ago. This is just personal mental shorthand, and it has no real significance as far as I can see. Emotions don't get in the way of evaluating propositions, it doesn't matter if you're hotheaded or cool, or how much you like an idea, just so long as you reason it out regardless of how you feel about it. For example, twenty years ago, I hated, hated, hated S-matrix theory, because I thought it was preposterous and I couldn't see how it could work, but as I learned more about it, I finally couldn't see anything wrong with it, and now I think it's the super-duperest coolest thing evar! So what. It's still right regardless of how one feels about it.
I would argue that emotion covers the entire range of human thought, and that separating out a given set of subjective experiences as emotion is ultimately misleading. This may simply be an oversimplification of the data @labreuer lays out in his answer. But I think that data suggests that emotion is not just a component of reason, but the central process of reasoning.
What makes a logical conclusion acceptable to your mind? One would like to imagine there is some internal computing system that objectively labels logic good or bad. But in the end, what convinces us of a logical truth is the feeling of clarity. This is an emotion. (I would claim it is a mild form of the very emotion of joy in power that Nietzsche promotes, the natural reaction to knowing one's will is in accord with reality.)
The same is true for memory. Not only is recall largely governed by emotional state, but I would argue that the certainty or doubt we have toward a memory is entirely a feeling, and emotion. Without that feeling of doubt or certainty, the memory fades. So knowledge is, in a very real way, also an emotion. You feel that you know things, and if you do not feel any certainty or doubt about them, they are not part of your fund of information. Things towards which you feel no real belief or disbelief, you are certain of remembering having learned, so you only kind of meta-know them to begin with, but your indirect relationship to the knowledge is still through an emotion.
If logic and memory are based on emotions, what is left of thought that is not governed by emotion? To my mind, nothing. So to whatever degree the whole of thought is reliable, emotion, being the whole of thought, is reliable.
Not just pseudoscience, but real science is when the feeling of clarity compels us to trust some perceptions and not others. And no, we cannot ever know science or other belief is not deceiving us. We can just chip away at the probability we are wrong by testing our feelings against outcomes.
As far as I know there were a couple of philosophers who tried to achieve exactly that, someone has to help me out on their names, though. They invented exercises to be free from emotions and bad thoughts, to think free without interrupting emotions and thoughts.
Nowadays that try is abandoned, at least in western academic philosophy and science (maybe it would be better to say that it is no scientific method, there may be people doing exercises to shut down emotions to reach more knowledge). Becoming free from emotions and thoughts is the main aim of meditation and some spiritual schools, though. Maybe eastern/asian philosphy can offer something like that.