@north,
Philosophinatic;164074 wrote:
Then why do we do anything at all? What can we hope to live for if there is nothing we "should" do?
There are two things that often get confused in a discussion like this. Motivation and morality.
All deterministic systems, like the brain and body, do things because they are motivated to do so. Fundamentally a body's desire to eat is no different from a rock falling off a cliff. That's the natural result of certain inputs to the system. There are more steps between inputs and outputs in some cases, but the principle is still the same.
The mind, on the other hand, is not deterministic. There is no inherent connection between what goes into the mind and what comes out of it. You can think anything at all. Thus, the mind doesn't have motivation. The mind only has morality. The mind picks a standard, and interprets actions based on how well they adhere to that standard. That is where "shoulds" come from.
The key difference is that absolutely anything at all can be a "should", but not anything can be a motivation. Motivations are limited. To oversimplify a bit, all motivations are inherently either the avoidance of pain or the seeking of pleasure. The mind doesn't experience pain and pleasure, it just knows that the brain does. The body is predictable, and with the exception of some wiggle-room on a few dimensions, unchanging. The mind is totally unpredictable.
Human nature is the brain/body stuff.
Unfortunately, "shoulds" only exist in the mind. Nature doesn't give a hoot about them. There is no particular reason anything "should" happen. Never. It's entirely subjective. The vast majority of the things humans do are entirely based on the motivation of their brain/body. The mind is just along for the ride, striving to make sense of it all after the fact. That is why people can be utterly convinced their life has no purpose, and can even explain the philosophy in great detail, but they can't kill themselves, and can't even let themselves die. Because the brain doesn't care about "shoulds." Human nature is to eat when you're hungry. People have been able to overcome that motivation in certain, limited situations, but I'm not convinced they weren't somehow disturbed. Anywho, that's another topic.