Good topic again here, man folks on here bring up stuff that can really challange the noggin.
I agree with most here, alcohol debilitates the reason center of the brain. It does not totally dismember it, but numbs it. The same principle coincides with the way teenagers and young adolescents make seemingly really dumb choices...the cortex of the brain is not developed and so simple 'reason' is much harder to come by.
I don't think, and haven't, I would ever go so totally out of my realm of reason, even while drunk, to murder someone, or to commit armed robbery....but there are some things that booze clouds reason just enough that I would never do while sober. I admit..I've driven totally smashed. All the while saying to myself that I can do this...it isn't that hard..no big deal. I've said things to my family that I would never have as well.
So...is it an excuse? Probably not for unfettered evil behavior...but it does extremely handicap our ability to make sound normal decisions...especially if you couple it with mental distress.
For me....affair no, but yelling something at my wife that I would not otherwise...yes.