It's not just "if you don't eat, you die". It's that you have a strong yearning to eat. Now that's probably an evolutionary adaptation to "if you don't eat, you die", but nevertheless I want to eat pretty consistently every day. Again, how is that different than a nicotine addiction? The only difference is that if I don't smoke, I won't die...
I think it is possible to make a coherent distinction between what has been termed “psychological addiction” and what has been termed “chemical addiction” without denying that the brain works by transport of, and reactions between, chemicals.
I don’t know how to precisely make this distinction because I am not a neuroscientist (neurobiologist?) .
But I’m still fairly confident that this distinction can be made in theory, and not just in practice.
Probably something about how some compounds (that generally aren’t present in the brain in substantial quantities) bind to some receptors, and this has such and such consequences, and then later when said compounds are not present, either some other receptors are plugged or inactive or are active, or some other chemicals are present in higher or lower than normal concentrations, in ways that cause problems which would in some ways be alleviated by the aforementioned compounds that are not typically in the brain in large quantities, and which would not be alleviated by whatever other compounds that would activate reward centers or whatever.
When someone is addicted to nicotine, they are addicted to specifically nicotine. When someone is addicted to alcohol, they are addicted to specifically alcohol.
