We do not like to pronounce any individual as alcoholic, but you can quickly diagnose yourself. Step over to the nearest barroom and try some controlled drinking. Try to drink and stop abruptly. Try it more than once. It will not take long for you to decide, if you are honest with yourself about it. It may be worth a bad case of jitters if you get a full knowledge of your condition. - Alcoholics Anonymous, pp. 31-32

The least effective way to persuade a person that he is alcoholic is to diagnose him as one. Besides, that is a job for the family. Look at what great results that got them.

Unfortunately, the self-diagnosis suggested here depends on a very shaky assumption, namely that an alcoholic is capable of being honest with himself. I don't often take issue with the Big Book, but it seems to me that by the time someone gets to our doors they have already tried this experiment in some form or another for years. It seems pointless to ask them to repeat it. As for suggesting that someone "[s]tep over to the nearest barroom," nowadays it is more likely that they will drive over, and worse, drive away.  I'm not sure I would like that on my conscience.

The important thing to take away from this paragraph is that ultimately an alcoholic's drinking experience is the most effective diagnostic tool there is. And the best way to draw attention to that is by sharing our own experience. As the new prospect listens to us diagnose ourselves he becomes increasingly able to do the same.