I often start the day glancing through Twitter to see if anyone has pointed to anything interesting to read. Today I skimmed several articles. One made me comment. It started with the sentence
"The minds of individuals are like parallel universes, forever inaccessible to one another."
This is a common enough idea in philosophy and neuroscience. Because the mind is a product of the brain and knowledge is a product of the mind, then knowing the mind is subjective.
But it is subjective in the same way that digestion is. You cannot be nourished by the food I eat. The nutrients are only available to my cells, because digestion takes place in my internal organs. This does not stop you from understanding that my digestion process is very similar to yours because it is based on an near identical infrastructure. Indeed it does not stop you from gaining objective knowledge of digestion as a process.
If you wanted to mystify the subject, to obfuscate in order to make it difficult to understand you could easily do so. A simple way to do this, is to insist on talking about digestion from an abstract point of view. e.g. nourishment. If eating and digestion are all about nourishment, and nourishment is entirely subjective then it becomes a Hard Problem. What is it like to be nourished by food? The nourishment you gain from eating a peach will never be the same as my nourishment. The digestive systems of individuals are like parallel universes, forever inaccessible to one another. True, but so what?
Conscious states are treated in the same way. We insist that the point of reference is an abstraction: consciousness. Because it is an abstraction it constitutes a Hard Problem - trying to explain abstractions in concrete terms other than the ones the abstractions were abstracted doesn't work, unless we do it metaphorically. But the clever clogs will always shoot down the metaphor because it is indirect.
Mental states are not directly accessible. But we can and do gain objective knowledge about other people's minds. If we did not then no communication would be possible. No drama would ever move us. No character in a novel would ever hold our attention. And so on. More especially we could not be a social animal. We could not cooperate, empathise, love, be altruistic, or be moral.
So yeah, of course we cannot *be* other people. We cannot have direct access to their mental states. But this does not mean that other minds are *inaccessible*, let alone forever inaccessible. We constantly have indirect access to other people's minds. I write these things to give you glimpses into mine.