While the nature of the Dhamma would seem to suggest that a nuanced and relativistic approach to ethics is essential, it is also true that the suttas are full of statements which, on the surface at least, seem to imply a rather more absolutist ethical stance. It seems to me that the general tendency of the tradition is to harden and rigidify ethical principles, with the unfortunate result that they become extreme, unworkable, and observed more in the breach than the letter.
An example of this is the term sasakka, which occurs in just three passages in the Pali canon (MN 61, MN 76, and MN 139). The basic meaning is straightforward. It’s from the root sak, to be able. It thus means “as much as one can”, which is the only sense given in the PTS dictionary. On the result page for this on SuttaCentral, note that the Concise dictionary gives a quite different sense: “surely, certainly”. This is from the commentary, which gives ekaṁsena in both passages.
The rather curious problem is that, of the two cases in which the word appears, one context definitively rules out the sense “certainly”. In MN 76 there is a discussion of four wrong ways of living the spiritual life. According to this, in such cases a sensible person would sasakkaṁ not live the spiritual life, or if they did do it they would not be successful. The translators render this as “assuredly” (Chalmers) or “certainly” (Bodhi, Horner). But this cannot be right—you can’t say something is certain, then immediately say, well otherwise there’s this other option.
Why does the commentary insist on this reading? I think the answer lies in the other context, at MN 61. There the Buddha tells Rāhula that if an act is unskillful, then that act should sasakkaṃ not be done. Again, our translators all use some version of “certainly”, reinforcing the idea that the ethical injunction is absolute. However, if we use the root sense of the word, we end up with a rather more flexible approach: “to the best of your ability”. I think the commentators wished to adopt a more absolutist ethical stance and rule out the possibility that ethical principles should be flexible.
In MN 139, sasakka appears in a similar context, but as part of a sequence of three stages. The topic is speech. If one knows speech is untrue, one should sasakka not say it. If it’s true but unbeneficial, one should train oneself not to say it. And if it’s true and beneficial, one should say it at the right time. Ven Bodhi has “on no account” for sasakka, while Horner has “if possible”. The commentary is silent on this point. Here, “on no account” is plausible, and it is hard to imagine the Buddha giving an opening for a deliberate lie, not after his strong words to Rahula that open MN 61. Still, we might render it “if at all possible”.
Given that the sense “certainly” is unjustified by etymology, and that it is impossible in one of the three contexts, I think we are justified in rejecting it completely. In all cases, we should render, “to the best of your ability, as far as possible”. Still, I have to admit that the reading in MN 139 troubles me.
And remember: the Buddha only ever asked us to do what was possible.