How do worlds build up inside our minds? – As an answer, I expect more than merely explaining how we visually perceive the scene in front of us, or reconstruct in front of our mind’s eye the object we are touching with our hands from the incoming tactile stimulation. My question is more complex.
Among the first things to find out, is, for sure, what it is that I call “world”. To give it a start, I might try describing it as “environments we experience”. When I go out, take my bike and ride to the grocery store, for instance, I do find myself within a world containing the house I live in, my family, the neighborhood I am riding through, the store I enter for shopping, so on and so forth. When I dream, I find myself in diverse situations, maybe on another planet or in another time. When I imagine future scenarios, vivid scenes are building up inside my head, I can watch them, manipulate them, act upon them. When I remember I recall—more or less accurately—past situations, past environments, and people I was in touch with around the time of memory. When I read a story about, say, wizards and witches, I can have them do magic, experience their joy and feel their pain. A similar thing holds for games and movies, though these worlds are not as much “inside my head” as the ones previously described (they are flickering on a screen instead). And, finally, worlds can be more abstracted away from our usual experience—e.g. if I try to solve a math problem and mentally rotate an n-dimensional sphere (not that I could).
All these are instances of what I take to be worlds; one thing special about the grocery shopping situation is this: we call it real. The major difference between the real world and other, so called imaginative, worlds is that it is thought of as a representation, an image, or a copy of the outer world, the environment we actually engage with. It perhaps deserves a special status in our minds since the real world is the one we all share. It is the one that can, contrary to all the others, be used as objective reference point (or at least we think so).
If we take the outer (real) world for granted (which I assume we should—but that discussion belongs elsewhere) then the question of how it makes its way inside our heads might be answered by investigating our perceptual apparatus. But, as already noted above, this is insufficient. What about all the other worlds? How do they come about? And, perhaps even more importantly, what distinguishes them—despite from having no currently externally present reference—from the mental copy of the real world? Is it even possible to make this distinction?
Related to these, further questions need to be considered. Among the most urgent ones are (1) What does such a world consist in? Can we talk about “images” or “representations” being “neurally coded” in brain tissue? If so, what makes our brains produce an imaginative world of trolls and wizards as opposed to one of dragons and unicorns? and (2) Once it is there, how does such a world change? How can I act within it? Why do things, say, move? This sort of change or manipulation of worlds might be what is commonly referred to as thinking. One might then ask further, are there, perhaps, necessary and sufficient conditions for thought? One difficulty is, however, to distinguish a merely observatory thought (e.g., seeing a squirrel run away or recalling the look of a person’s face) from one in which we actively engage with our environment (e.g., dreaming of climbing a rock). Both inevitably are cases of thought but only the latter obviously involves world-manipulation. Taking a closer look, I suspect, even cases of apparent observation will, after all, include some sort of manipulation.
Thus far, I have laid out some questions answering which—I hope—will be of help to eventually approach the big question. It is time then to ask who can provide answers. Scientist are researching in memory, visual processing, attention, conceptual schemes, empathy, the connection between mind and body, consciousness and a bunch of other phenomena. But how to put all this together? Will a philosophical, neuroscientific or psychological approach turn out most fertile? There is a lot more to be said here; for these paragraphs are only the gist of a giant puzzle.