This reminds me about a theory I spoke to some relatives about. I said, is it possible that your mind is all that is true, and that the rest of the world is your own hallucination?

A prime pop-culture example would be the Star Trek episodes The Menagerie and Shore Leave. Telepathic aliens create a world for some of the crew members out of their memories, and they think that it is real.

It's possible that life is but a dream, but it's also irrelevant. We would live our lives the same either way.

Common sense tells us that our existence is real. Literally. The sense we hold in common about reality is largely correct, to the limits of our current comprehension of things. (An example of such limits: We can't hear stuff dogs can. Hell, adults can't hear frequencies teens can.)

Why is it largely correct? Because our sense of things is constantly verified by a large number of people, reducing the possibility of substantial error. And basically, errors in our sense of things can lead to harm or death.

In terms of fallible perceptions, lets look at the only two "instincts" (or unlearned behaviors) that have ever been found in humans. A human infant will react with fear to items suddenly presented and to a perceived loss of support from the surface preventing them from falling (this was tested by placing an infant on a board some distance from the floor, covering that with a firmly support piece of clear Plexiglas, and then removing the board blocking the view of the floor below.

This startle response and fear of falling -- fallible perception? Or a survival mechanism?

However, we also need to account for instances of mass hysteria. We can be subject to what is called folly-a-deux, A condition in which symptoms of a mental disorder, such as the same delusional beliefs or ideas, occur simultaneously in two individuals. We could perhaps have occurrences of "folly-a-culture", in which we are all insane. However, instances of that are largely rare.

Except perhaps those who believe in god. Studies have should that we have an innate ability for mystical experiences, which subject us to a need to interpret, and which are commonly understood as an encounter with the holy. A similar shared belief, perhaps from the same source, are superstitions.

I'm not presenting a clear argument one way or another as the situation is complicated. Maybe we experience or life largely grounded in reality, and of course fallible perceptions. Or we can have a thin veneer of sanity, covering a mass pit of "insanity" or illogic. Consider our experience in dreaming...

Oh well. Some food for thought.

Life is real because there are other humans interacting, however, an imaginary mind can perceive fantasy.