I am conscious that these Buddhist asides may feel off-topic for other participants, so I will try be as brief as I can (without reducing the complexity of the issue!), and then leave the matter as it is.
Remember that there is no such thing as a single, catholic, monolithic ‘Buddhism’. There are many different Buddhisms, many forms of Buddhism, which have existed alongside each other from the earliest time-period. Indeed, one needs to understand somewhat the historical context of the time of the Buddha to see why these different interpretations took hold.
In the centuries before the Buddha was born Vedic culture was concentrated in the north west, in a region called Kuru-Pancala, while the central Gangetic culture to the east (which some historians have called Greater Magadha) remained relatively independent. There was some cross-over between the two cultures, but their relative independence is important to be aware of.
This Greater Magadha region was responsible for producing Jainism and Buddhism. For early Jains, all physical and mental activity involved wrong-doing or harm of some kind, and so they projected absolute non-activity (physically and mentally) as the highest goal of their religious life (which sometimes included deliberate starvation, resulting in death).
When Buddhism appeared it continued to have an ongoing correspondence and dispute with these ideas. Buddhism necessarily refined the Jain outlook, rejected its exaggeratedly ‘physicalist’ understanding of harmful action, and replaced it with an emphasis instead on our psychological intentions. For Buddhists, harmful actions were to be dissolved through a combination of meditative states, moral intentions, and correct insight into the nature of reality.
However, despite the Buddha’s clear rejection of these pre-Buddhist ascetic practices, some Buddhist scriptures continued to accommodate many of these ideas, and so the more ‘physicalist’ interpretation of harmful action remained as a background in the development of mainstream Buddhist culture.
There was also the issue of what the Buddha meant by his insight into the chain of dependent causation (sometimes called ‘dependent-origination’) - a doctrine that would have a long evolution in Buddhist philosophy. There is no space to go into it here, but some early Buddhists apparently believed this chain of causes (leading to suffering) began first of all with sensual desire, thirst (in Pali, tanha); while others believed it began with avijja (Sanskrit avidya), meaning cognitive ignorance. Because the Pali scriptures (together with the monastic rules codified for monks and nuns) contain both views - sometimes emphasising the evils of sense desire, sometimes pointing to the need for cognitive insight - Buddhist culture absorbed them both and developed each one accordingly.
Indeed, some scholars have argued that the difference which gradually arose between two different forms of Buddhist meditation - samatha (calming) and vipassana (insight), which became (and still is) a big issue in Buddhist cultures - was a direct consequence of this hermeneutical tension in the Pali canon:
i.e. between the idea that suffering is caused by sensual desire, or by cognitive ignorance. The latter is supposed to be cured by vipassana (insight) meditation, while the former is cured by samatha (calming) meditation. So it is an ongoing point of dispute in Buddhist thinking.
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