To put it in Bhante Kumara’s words, as of September 2014:
In sammā·saṅkappa, we find abyāpāda·saṅkappa and avihiṃsā·saṅkappa
(besides nekkhamma·saṅkappa). I still can’t see why is there a need to
include avihiṃsā·saṅkappa. Shouldn’t abyāpāda·saṅkappa cover it?
I have been wondering the same thing for a while, and judging by the number of hits on the corresponding thread at DW, so do quite some people.
The answer appeared to me while staying in a monastery where when it rains there are lots of snails crossing the paths, and if we are not careful enough, we easily crush them unintentionally. Then it stroke me that harming others does not necessarily happens intentionally.
Then the difference between avihiṃsā·saṅkappa and abyāpāda·saṅkappa could just be intention: there is harming others intentionally (with byāpāda) and unintentionally (without byāpāda, therefore not covered by abyāpāda).
One example could be that of Jain ascetics sweeping their path wherever they go to make sure they are not going to step on any insect. There would have been no ill will against the insect, just harming out of carelessness, so they felt compelled to do this. Another example is when a monk gathers wood for the fire to wash/dye robes: he might put it in a place where ants or insects won’t settle inside, in order to prevent them from being harmed, without ill-will, just out of expediency, as it seems to be allowed by the Vinaya, according to Thanissaro Bhikkhu.
Then abyāpāda·saṅkappa would be the aspiration of non ill will or benevolence, and avihiṃsā·saṅkappa would be the aspiration not to harm others, even unintentionally, which expresses itself by making choices to that end, like organizing oneself to inflict minimum harm on animals, (for lay people) becoming vegetarian or not buying from industries that resort to exploitation of poor people etc.
Other example is refraining harming others with good intention, i…e., with non-ill will. For example, there is a bloody ruthless dictator, who one day decides to go for a walk alone in the forest. Unknown to the dictator, you have been meditating for days in retreat in the same forest & you recognise the dictator. You have the chance to kill the dictator, which would result in many people not being murdered, raped & tortured. If you follow the 8 fold path, you are not allowed to harm the dictator, even though your intention comes from good-will.
In some religions, there is the death penalty for major & minor sins as necessary duty to God and the creation of a perfect sinless society. This is another example of violence without ill-will.
In 2003, the military forces of the USA, UK & Australia invaded Iraq for the purpose of liberating the Iraqi people from tyranny & to save the whole world from weapons of mass destruction. For members of the public who are very gullible, this was another example of harming some others without ill-will. It was a good-will mission. Most modern war propaganda is based on harming others with good-will.
In summary, the teaching is most important for Buddhism. This teachings prohibits monks doing violence for any reason; even if to protect the Buddha, Dhamma &/or Sangha; or more simply, wanna-be Zen masters who wish to beat their students with a stick or wanna-be Wrathful Deities.
Yes, this is also how I see it. Both have to do with intention but there is a difference between non ill-will (intention of goodwill, benevolence) and non-harming (intention of harmlessness, compassion)