@ y not:
Moral conduct or sila of a normal human is breakable. When one is highly influenced by an external sense event, one’s morals may not hold. For example, one could be abiding by “not to steal” precept for most of one’s life, but could be tempted to steal on the spur of the moment if the possibility to gain a million dollars comes up.
Ariyakanta sila of a Sotapanna means a Sotapanna’s mind is not capable of doing an “apayagami action” (a deed of kammic consequences in getting a rebirth in the apayas), UNDER ANY CONDITION.
But we need to realize that a Sotapanna is capable of violating any precept that is not an “apayagami act”. Violation of any of the five precepts, in many cases, is not an apayagami act. For example, telling a lie is an akusala kamma, but it is not an apayagami act. (P.S. I should have said: For example, telling a lie is an akusala kamma, but not necessarily an apayagami act).
This is something hard for most people to understand: A Sotapanna’s “built-in capability” not to do any apayagami actions is rooted in his/her change of world view. Once it sinks in the mind that it is not worthwhile AND dangerous to do anything truly immoral (these are the apayagami actions), with the comprehension of the anicca nature, the mind will AUTOMATICALLY reject such actions.
One (a Sotapanna) does need to think and realize the danger involved in such action. No matter how enticing the sense input is, one WILL NOT be able to do an apayagami action. It comes mainly from getting rid of wrong views: The 10 types of micca ditthi AND the first glimpse of the anicca nature (that it is not possible maintain anything to one’s satisfaction in the samsaric time scale).