I've found that a lot of Buddhists when asked don't know precisely why liquor was prohibited by the Buddha. The general response is that it makes one unstable and act foolishly leading to lose of mindfulness. However, the real reason it seems according to the records of various Vinaya accounts, all of which incidentally differ in the fine details of the incident which led to the prohibition, was a lot more utilitarian. Basically, one of the monks became quite intoxicated and made a scene, so the rule was laid down prohibiting alcohol.
The incident is recorded in the Mahāsāṃghika Vinaya as follows.
《摩訶僧祇律》卷20：「佛住拘睒彌國。廣說如上。爾時拘睒彌界有惡龍。名菴婆羅。能使亢旱不雨苗稼不收。人民飢饉。如是種種災患。時尊者善來比丘往降惡龍。如善來比丘經中廣說降伏惡龍已。乃至國土豐樂人民感德。知恩報恩。有五百大家為善來故。各立常施幢幡施設床座。請僧供養。別請善來比丘。其所造家。則設種種美食。時有一家施食之後。因渴施酒色味似水得而飲之。還向精舍。爾時世尊大會說法。酒勢發盛。昏悶躃地。當世尊前舒脚而臥。佛知而故言。是何比丘在如來前舒脚而臥。比丘答言。善來比丘飲酒過多是故醉臥。佛問諸比丘。此善來比丘先曾晝寢不。不也世尊。復問比丘善來。未醉之時頗曾佛前舒脚臥不。不也世尊。復問比丘多飲酒已。欲使不醉可得爾不。不也世尊。復問諸比丘。設使善來比丘不飲酒時聞說微妙不死之法。當欲失是善利。不聽受不。不也世尊。佛語諸比丘。是善來比丘本能降伏惡龍。今者能降蝦蟆不。答言。不能。佛言。設使菴婆羅龍聞者生其不樂。從今日後不聽飲酒。」(CBETA, T22, no. 1425, p. 386, c13-p. 387, a4)
The Buddha was residing in the country of Kauśāmbī teaching as was mentioned above. At that time in the realm of Kauśāmbī there was an evil nāga named Āmra who had caused a drought where the rain did not fall and the crops were not harvested. The people were starving and there were various calamities like this. It was then that the bhikṣu Venerable Svāgata went to placate the evil nāga. As it is explained in the *Svāgata Bhikṣu Sūtra, after placating the evil nāga the country celebrated and the people felt gratitude, aware of the kindness bestowed upon them and wanting to repay it. It was on Svāgata's behalf that five hundred great families each offered up hanging banners and setup seats, inviting the monks for offerings. They made a special invitation to Bhikṣu Svāgata. The households which made [the offerings] provided various kinds of delicious foods. It was then that after one household had offered food that due to his thirst they offered alcohol which appeared as water whereupon he drank it. He returned to the monastery where the World Honored One [the Buddha] was teaching the Dharma in a great assembly at the time. The influence of the alcohol was all too much as he became unwell and fell onto the ground. It was in front of the World Honored One that he stretched out his legs and passed out.
The Buddha was aware of this and thus said, “Which bhikṣu is it here that has stretched out his legs and passed out in front of the Tathāgata?”
The bhikṣus replied, “Bhikṣu Svāgata drank much alcohol and thus has become inebriated and passed out.”
The Buddha asked the bhikṣus, “Has Bhikṣu Svāgata here ever slept during the day?”
“No, World Honored One.”
He again asked, “Has Bhikṣu Svāgata prior to being inebriated ever stretched out his legs and passed out in front of the Buddha before?”
“No, World Honored One.”
He again asked, “The bhikṣu having drank too much alcohol, if he wanted to make himself un-inebriated, would it be possible to do this?”
“No, World Honored One.”
He again asked the bhikṣus, “Suppose Bhikṣu Svāgata at a time when he had not drank alcohol heard an exposition on the excellent and immortal Dharma – would he want to lose this benefit and not listen to it?”
“No, World Honored One.”
The Buddha said to the bhikṣus, “This Bhikṣu Svāgata was originally able to placate an evil nāga. Now, could he placate a toad?”
They replied, “He could not.”
The Buddha said, “Suppose Āmra the nāga heard this – it would provoke his displeasure. From today onward I will not permit the drinking of alcohol.”
It might have been a practical rule to be laid down at the time, but alcohol became seen in later Buddhism as something of an evil substance to be shunned. This is perhaps a natural outcome that would follow prohibiting the substance in a religious context.
Nevertheless, it begs the question if the prohibition against alcohol is actually necessary. I say this because the Buddha is also on record having told Ānanda that the sangha could abandon all the minor precepts, but unfortunately as the story goes Ānanda failed to inquire as to what the Buddha meant by "minor precepts," which led to the assembly not reaching a conclusion and Mahākāśyapa declaring that all the precepts would be kept and that was that.
I'm not advocating that we abandon the precept against alcohol, but I have come to wonder if it is an actual necessity. I say this because before the prohibition against alcohol was enacted, the monks presumably and clearly did consume alcohol and the Buddha would have been aware of this and did not tell them to stop it. It was only when one monk went too far that the rule was laid down.
In that sense it is a minor precept and we might assume that consuming alcohol is not so much of an issue. Historically, many Buddhist cultures have not given it much emphasis. Marpa and Milarepa are on record as having consumed beer. In China and Japan there were and still are (at least in Japan anyway) monks that consume liquor. The Japanese got the expression "prajñā soup" (般若湯) from China.
So, the question is, are precepts against alcohol consumption a strong necessity?
