What does it feel like to feel empty?
It literally feels like nothing. It's a blank, like an internal state of nonexistence.
Does it mean lacking an integral sense of self or does it simply mean you are frequently underwhelmed by everyday experiences and cannot be easily amused or maintain a lasting state of amusement?
It's both and more/less. The recognition that there is no integral self and nothing to be felt in the absence of external stimuli.
It seems that for these types, they look to the outside for things to fill the void rather than within themselves. But the loneliness seems incurable as well. Why is that? What makes an island a paradise for one man and a place of imprisonment/exile site for another man?
It's not a void. It's a state of non-feeling. Boredom isn't even possible during those times. There's no loneliness, no desire for something else. There is literally nothing there. It's empty.
I don't really have a lot of ambition, and it's partly due to anxiety and partly because I am genuinely satisfied with simple comforts and my thoughts, but I've noticed that those who feel empty can be quite ambitious because they always want more. Filling the void is like tossing things into a black hole.
It's not a void. It sounds like you are referring to the feeling of "hunger". This is a separate state. Hunger is better than empty as it causes the seeking out of external stimuli while empty is just nothingness, no feeling, no ambition, nothing. Nothing will ever fully satisfy the hunger state. It is nearly ever-present. During the times it ceases, empty takes over. Hungry is preferable to empty.
However, once they become existential the ambition seems to go out the door--yet they maintain the standard for life they had before.
Empty will pass. It is always there lurking in the background, but hunger can take over and become primary drive. When one is empty, there can be no action.
I see this with my brother. I think he was prone to being unsatisfied since childhood. He has battled addictions for over a decade, can't seem to hold a job for long, and has not truly invested in himself. He definitely has a nihilistic, hopeless attitude about his life...yet he still seeks prestige--spending money on designer clothes and upscale restaurants when he supposedly can barely pay rent. He works out, pursues relationships, and tries to keep his mind sharp. He looks up to our other brother, but whenever the means to achieve similar success is acquired, he throws it all away.
This is not the same as an existential crisis, addiction or depression. Those hold that there is an internal self to be affected. Hunger and empty are not intentionally self-defeating or self-destructive. It just is. There are no other feelings to feel, except pain or euphoria which offer a temporary diversion.
Presently, he is in a Christian halfway house type thing and claims to have been 'saved' to the point of having spoken in tongues. This gives him purpose, but why does he need it? Is finding a 'purpose' the only way to beat an addiction?
One's highest purpose, in my opinion, is one's self. Whatever makes him feel better I suppose, though external purpose seems to be an fulfilling and constraining purpose. Freedom is preferred to conformity. I can't speak to instances of addiction however. I don't know.
I'm rambling...I guess I'm wondering what it's like in the mind of a person who feels chronically empty. What does perpetual unfulfillment even mean? What would make you feel fulfilled?
Empty is not a state of unfulfilled. There is nothing to be filled. There is nothing.
On a more broad note, what is everyone's philosophical view on life...
Life is about maximizing pleasure. There are times when restraint must be exercised or things done that are not pleasurable for a greater reward of pleasure in the future. It's effort versus payoff.
...and what is your default internal state?
Empty/hungry.