There's no real "definition" for addiction, it's a psychology thing, so soft science. To me, "clear harm" is best if it's recognized by the person doing it, but that's not always the case. An alcoholic who doesn't have a bad liver and has never run someone over is still an alcoholic.
Society views smoking as harmful to your health, whether that's true or not, it's something that's "known."
DSM-IV-TR Criteria for Substance Dependence
A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by
three (or more) of the following, occurring within a 12-month period:
- Tolerance, as defined by either of the following:
- a. a need for markedly increased amounts of the substance to achieve intoxication or desired effect
- b. markedly diminished effect with continued use of the same amount of the substance
- Withdrawal, as manifested by either of the following:
- a. the characteristic withdrawal syndrome for the substance (refer to Criteria A and B of the criteria set for opioid withdrawal)
- b. the same (or a closely related) substance is taken to relieve or avoid withdrawal symptoms
- The substance is often taken in larger amounts or over a longer period than was intended.
- There is a persistent desire or unsuccessful efforts to cut down or control substance use.
- A great deal of time is spent in activities necessary to obtain the substance, use the substance, or recover from its effects.
- Important social, occupational, or recreational activities are given up or reduced because of substance use.
- The substance use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance.
Specify if:
With Physiological Dependence: evidence of tolerance or withdrawal
Without Physiological Dependence: no evidence of tolerance or withdrawal
For most people I'd say smoking fits in there, and nicotine for most of us is part of the treatment. There's no evidence that nicotine use,
in a non-tobacco user, would develop into dependence. That's something I'm sure you, I, and many others on this forum will continually have to try to inform people about.