Hi Alyssa and meme,
Alyssa I agree with you that we often stop too soon and interpret the excuses we want to see. I'm not offended at all, and wouldn't be even if I disagreed with you.
I referenced dependence because of the start of the thread...but maybe an easier example is to start with mental illness. I accept that diabetes is a condition brought on by genetics, environment, and experience. I was not a bad person for getting it, and don't think I'm a bad person for taking the insulin to manage my diabetes. Yet I know people who think depression is "all in your head", and that individuals who take anti-depressants are "weak" or not trying hard enough to manage their condition. In short, they don't have a strong enough will to stop their depression. I accept that depression is caused by a combination of genetics, environment, and experience. So why would this difference between diabetes and depression exist? I typically find that it has to do with the idea that "mental" processes are different than "physical" ones, and that we should have more control over our mental lives. However, if we accept that the brain is an organ that follows the same rules as our pancreas...there is no difference. I have friends with bipolar, ADHD, and borderline personality disorder who all refuse to take medication because of this concept.
Going back to dependence, if we now connect A and B, if the brain follows the same rules as the pancreas for developing illness, how is dependence different? Yes, someone took a drink, but I got a virus (or immunization or whatever else one might think), and the depressed person experienced the death of a family member. Gambling addiction and internet addiction are now recognized as addiction even though there is no direct ingestion of an addictive substance. This is because they involve the same symptoms and brain activation as "drug" dependence. Addiction has even been recognized in animal research...so some might need to reevaluate how they interpret addiction, animals, or both. Rats with electrodes implanted into their "reward" centers will pull a lever to stimulate the area until they collapse from exhaustion (does this sound like anyone you know?).
So now if we remove the distinction between diabetes and addiction, how does will power come into play? I find that you can't formally assign blame in either situation, and the blame game does no good for anyone (thx meme). If willpower works for some and not others, why? What is it? If willpower is ineffective, as it is in many situations, I find it not worth considering. In psychology (my field of choice) I think the terms you would be interested in are Motivation and Resilience (why do people do what they do, and how do they stay strong when faced with bad situations). These are not in my area, but if they interest you, a career could be developed around studying them. Thanks for reading while I shout from my soapbox.