The assumption that nature is all there is, and that nature has been governed by the same rules at all times and places, makes it possible for natural science to be confident that it can explain such things as how life began.
Every state in America has an end of life directive or durable power of attorney provision. For the peace of mind of your children and your spouse as well as the comfort of knowing the government won't make these decisions, it's a very popular thing. Just not everybody's aware of it.