Upvote:0
This answer says that the fifth precept was added a little later:
Alcohol is frequently absent from lists of prohibited activities, including the famous Pansil, i.e., Five Precepts. There is a fourfold version of pansil called the Four Restraints. As to why this is the case, the answer is that it is because the Buddha did not prohibit alcohol for the first eight years of the sangha. The Buddha only prohibited alcohol when a monk got drunk and passed out, embarassing the sangha.
This comment adds some support for that statement -- for example you can see that the section titled "The Short Section on Virtue" in DN 1 only mentions the first four precepts.
Upvote:1
Thus I have heard...a monk got drunk and pointed his feet at the Buddha (a serious sign of disrespect in the Buddha's culture). At this, the Buddha banned the drinking of alcohol based on the fact that it can cause such serious lapses in mindfulness so as to lead a monk to show an extreme lack of respect.
Upvote:8
The five precepts are mentioned in Dhammika sutta. The main reason for teaching the fifth precept is said to be that intoxication easily instigates people to break other precepts by concealing the seriousness.
"Now I will tell you the layman's duty. Following it a lay-disciple would be virtuous; for it is not possible for one occupied with the household life to realize the complete bhikkhu practice (dhamma).
"He should not kill a living being, nor cause it to be killed, nor should he incite another to kill. Do not injure any being, either strong or weak, in the world.
"A disciple should avoid taking anything from anywhere knowing it (to belong to another). He should not steal nor incite another to steal. He should completely avoid theft.
"A wise man should avoid unchastity as (he would avoid falling into) a pit of glowing charcoal. If unable to lead a celibate life, he should not go to another's wife.
"Having entered a royal court or a company of people he should not speak lies. He should not speak lies (himself) nor incite others to do so. He should completely avoid falsehood.
"A layman who has chosen to practice this Dhamma should not indulge in the drinking of intoxicants. He should not drink them nor encourage others to do so; realizing that it leads to madness. Through intoxication foolish people perform evil deeds and cause other heedless people to do likewise. He should avoid intoxication, this occasion for demerit, which stupefies the mind, and is the pleasure of foolish people.
http://www.accesstoinsight.org/tipitaka/kn/snp/snp.2.14.irel.html
As for creating a schism in the sangha, my understanding is that this is not applicable for laypeople. Only monks are capable of causing a split. But a layperson can be a cause indirectly which isn't a severe offense.