So, when a philosopher says something like "science cannot tell you what it's like to be thrown into life", well ...
... if philosophy (or literature or whomever) has identified some actual feeling or idea or internal process, that is, some kind of experience, which they assert as true subjective experience, then that is something that could be investigated from a biological perspective ... as a cognitive science experiment.
So, put some people in fMRI machines, ask them to evoke that experience, and tell the investigator when they're feeling it, and then the investigator can look to see what patterns of brain activity are common at that moment among many subjects, find the common localized structures, compare to other structures, find elements, field effects and compositional mechanisms, etc.
The same can be done with, say, a "sense of individuality" or a "moment of free will" or an enjoyment of "being in the moment". If the phenomena are common experiences, then we can start to identify them. We won't find out much, because understanding of the brain is in such a primitive state, but at least existentialism can be brought back under scientific review, and we can separate the good stuff from the bad.
Yes, it's a little ironic, since the original idea was to emphasize individuality. But irony shouldn't stop us from learning something new about the common human experience.