3. Nobody's drinking "socially"
The Centers For Disease control makes clear what seasonal anecdote, holiday police budgeting and campus riots only allude to: St. Patrick's Day is a binge drinker's playground.
The National Institute on Alcohol Abuse and Alcoholism defines binge drinking as a pattern of drinking that brings a person's blood alcohol concentration to 0.08% or above. This happens typically when men consume five or more drinks and when women consume four or more in about two hours. If you wait for an hour for your one Guinness, drink it at a moderate pace, chat with friends for about an hour and leave, you're doing just fine.
Of course, if you feel the value of the amount of time spent in a bar can be measured only in the number of drinks you have there, there's a chance you're going to be having a little more than two per hour. As the CDC notes, that doesn't make you an alcoholic: It just makes you perhaps not the healthiest person on Earth and part of the problem when governments decide to tax beer more heavily, limit liquor licenses and restrict sales points.
Oh, and it also makes you 14 times more likely to drink and drive, which brings us to our next point: