Hi again
Thanks very much for the compliment about my articles. I often use a bit of humour but I definitely do take these questions seriously.
I've never been convinced by the argument that the external world is nothing but the product of my (internal) imagination or mind. It's possible, but how would we ever know?
It certainly is the case, however, that our contact with the external world depends on our brain's interpretation of certain sensory stimuli. But that's a different issue.
To answer the point about the dead person, it seems to me that what happens when someone dies is not that the world ceases to exist. If I die before you, you won't suddenly think that there is no world anymore. What happens is that the dead person ceases to experience the world which the rest of us continue to experience. It isn't the world that no longer exists, it's the person.