In terms of dreams, do humans have any insight as to what causes them? For example, if someone were to have a reoccurring dream, is there any humanly possible way of knowing why this is? Are they simply a reflection of daily life, an indicator as to what our future holds, or is it our brains way of forgetting that certain things ever happened?

Your question is an interesting one, but on one reading not one a philosopher has any particular claim to being able to answer. Whatever we know about the causes and function of dreams, we presumably know on the basis of empirical investigation—in psychology and/or neuroscience, most likely.

That said, there are a few comments that don't seem out of place for a philosopher to make. It does seem possible that we might learn why people have recurring dreams. Careful collection of lots of cases might reveal some patterns, and those patterns might suggest hypotheses that we could actually test. (We might, for example, be able to predict when people are likely to have recurring dreams, or even learn how to induce them.) It's not utterly impossible that they predict the future, but if that calls for the future influencing the present, it flys in the face of a good deal of what we normally take ourselves to know about the world. And as for being a way for the brain to forget, we'd need a much more specific hypothesis before we could investigate that.

Answers to many questions about dreams will most likely come from science, but there may be something left over. We often find ourselves wondering about the meanings of dreams. Compare: science might eventually tell us a lot about how humans came to be story-tellers and what adaptive function, if any, storytelling serves. But answers to those questions aren't what we have in mind when we ask about the meaning of a story like The Turn of the Screw. Dreams have a lot in common with stories and so there are interesting questions not just about the meanings of individual dreams but about what it means to say that dreams have various sorts of meanings. This is where philosophers might well have something to contribute, though I confess that I don't have anything enlightening to add.

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