“In some circumstances we have gone out deliberately to get drunk, feeling ourselves justified by nervousness, anger, worry, depression, jealousy or the like. But even in this type of beginning we are obliged to admit that our justification for a spree was insanely insufficient in the light of what always happened. We now see that when we began to drink deliberately, instead of casually, there was little serious or effective thought during the period of premeditation of what the terrific consequences might be.” (Chapter 3, Big Book)
If a fire starts in a forest, it can start for many reasons. Arson. Lightning strike. Campfire. Sunlight concentrated through glass. Discarded match. Car crash. Chemical spill. Once it starts, exactly the same mechanism causes the fire to propagate, out of control. How the fire propagates has nothing to do with the original cause.
It’s like that with my drinking. I might start for a dozen ‘reasons’, on a dozen different days, but the mechanism responsible for the second and subsequent drinks was entirely different to the mechanism responsible for the first. With fire, the second flame is caused by the first, regardless of what caused the first. With drinking, the second drink is caused by the first, regardless of what caused the first.
Turning to the first drink:
Looking for reasons for the first drink is a reasonable exercise when trying to explain why someone drinks moderately. These reasons (social awkwardness, unhappiness, boredom, tension) are arguably legitimate reasons for moderate drinking.
Once I developed the regular habit of very destructive drinking, whose destructive extent was never precisely what I planned, all such reasons became irrelevant. The legitimate reasons for moderate drinking cannot even be discussed when moderate drinking is not one of the options on the table. When the only two options on the table are sobriety and excessive drinking, such reasons are easily defeated: excessive drinking brings increased social awkwardness due to my behaviour drunk; excessive drinking brought huge unhappiness, was often profoundly boring, destroying any real ability to take an interest in interesting pursuits or subjects, and drinking excessively often made me nervously aggressive.
Any ‘reasons’ I give for such drinking are therefore insane rationalisations. The only reason for having the first drink is that I have the impulse to drink and lack a mental defence against it.