It seems to me that no action stands on its own.
For example, with the rains’ return to Sebastopol over the last week I’ve been continually struck with an urge to smoke tobacco. I quit a month ago and am thoroughly committed to avoiding the stuff, but the niggling voice of temptation reminds me that the cool moist air would nicely complement a cigarette’s warm earthy taste. So why not have just one?
Because it wouldn’t be just one.
I currently have a mental barrier preventing me from smoking: I’d be breaking a month-long streak of abstinence! After I smoked the one, I would no longer have the streak to dissuade me from another. Also, I can’t buy just one cigarette. Acquiring the materials for one cigarette (papers, filters, tobacco) would leave me with the materials for a few dozen cigarettes. I could roll the second cigarette inside, without walking to the store through the rain. Finally, smoking a cigarette would refresh the craving pathway in my mind, making it just as difficult to resist another cigarette as it was on the day I decided to quit.
In other words, there are several types of barriers between the first cigarette and I. I can only overcome them by eroding them, and once I do, the habit can run wild.
I believe that the future is a landscape of probabilities and every present action shapes that landscape. Smoking doesn’t guarantee that I’ll get cancer – but it does increase the likelihood.