Our parsha relates that Noach began to work the land and planted a vineyard, and made wine. His subsequent drunkenness had tragic consequences (Bereshit 9:20-21, see Rashi). Drunkenness also led people to act against their better judgment in the case of Lot (Bereshit 19:30-38) and of Yitzchak’s blessing (Bereshit 27:25. Of course in all of these cases the drunkenness served the plan of HaShem; our point is that it had a negative effect on people’s moral judgment.)
On the other hand, drinking seems to be a positive influence in the case of Eliezer’s stay in the house of Betuel (Bereshit 24:54), where it helped create a sense of fellowship between Rivka’s family and Eliezer. And the Yosef and his brothers did not drink wine until the day when they all feasted together; then they became drunk (Bereshit 43:34 and Rashi). Here also the drinking seems to have created a joyful relationship among the brothers.
One evident difference between the negative and positive instances of drunkenness is that in all of the negative cases the drunk person drank alone, while in the positive cases people drink together. Various halakhot also seem to bear the message that wine can have a positive influence specifically when people drink together.
The clearest example is that of “hatov vehametiv”. This is a special blessing made on a change of wine. There is a special joy in drinking one wine and then having another, different or better variety brought in, and our Sages established a special blessing for such an occasion, praising HaShem “Who is good and does good” or alternatively “Who is good and then does more good”. While this seems to be an ordinary blessing of praise, most Rishonim concluded that this blessing, like the other “tov umetiv” blessing on good tidings, is said only if the enjoyment is shared with others (SA YD 175:4)
Another example is that of saying Birkat HaMazon after meals on a cup of wine. While this seems to be an ordinary kos shel berakha (cup of blessing) like those of kiddush and of havdala, custom is according to the Zohar, which states that “benching” is said over wine only if there is a zimun of three men (MB 182:4).
Drinking has the effect of lowering our inhibitions. This has the ability to break down the barriers of alienation among people, which is near the very essence of joy. But it also has the potential to lower our watchful guard against sin. When we drink together, especially in the framework of a mitzva, then the positive aspects of drinking are augmented and the negative ones relatively minimized. The opposite occurs when a person drinks alone.
A halakha with a similar message is that it is forbidden to drink intoxicating drinks in a tavern together with non-Jews (YD 114). While we are commanded to maintain positive friendly relations with our non-Jewish neighbors (YD 251:1, 335:9, 367:1), we still maintain a respectful psychological distance. We seek to completely break down the barriers between men only with our fellow Jews; in appropriate circumstances, moderate drinking can contribute to this goal.
It goes without saying that a person should never get so intoxicated that he is prevented from serving HaShem with all of his faculties, including saying blessings, prayers and so on (MB 695:4).
Rabbi Meir has recently completed writing a monumental companion to Kitzur Shulchan Aruch which beautifully presents the meanings in our mitzvot and halacha.