[IMPORTANT: Please read this post, or take into consideration the following.
This discussion, and its topic, in no way implies that “jhāna isn’t needed for the path of stream-entry/once-returner…" (or “the path as a whole”). It simply means that it’s not impossible for one to reach sakadāgāmimagga without jhāna… In a similar way that it’s not impossible to run a 100-meter sprint in 10 seconds (the world record is 9.53 seconds). It’s possible, but unlikely…
Developing higher levels of concentration—i.e., developing sammā-samādhi—is a crucial and required component of the path. Even if you don’t reach jhāna, you are still developing higher levels of concentration. Concentration/sammā-samādhi is a required condition for the arising of wisdom/paññā—and without wisdom/paññā (and at least some development of higher levels of concentration), there can be no progress on the path. Meditate and at least attempt to develop jhāna—don’t be discouraged, and after weeks, months, or if needed, a year of (consistent) meditation practice, eventually you’ll reach it (and even if you don’t, you are still developing higher levels of concentration).]
The Buddha does describe sammā-samādhi as being the 1st to the 4th jhāna a very large number of times in the Suttas. However, from not ever having come across a similar passage (please post if you have), he doesn’t say anything along the lines of “sammā-samādhi (right concentration) is jhāna and nothing else.” Furthermore, he also hasn’t distinctively said that “jhāna is required to attain Nibbāna" or that “without having reached jhāna, Nibbāna is imposssible”(again, please post if you have found such a passage).
To infer such statements as the above in quotation marks, in comparison to what the Buddha has said, would be abrupt conclusions. However, to come to the conclusion that there is more to sammā-samādhi than just jhāna, and that jhāna is not a requirement to attain Nibbāna, simply from the absense of such statements by the Buddha, would also be abrubt conclusions.
So, the questioning is…
While sammā-samādhi (right concentration) is often described in the Suttas as the 1st, 2nd, 3rd and 4th jhānas, does this mean that sammā-samādhi is only jhāna and nothing else?
While it would be thought that jhāna is requirement for attaining Nibbāna, there are many accounts in the Suttas of people spontaneously reaching Nibbāna, possibly without much thorough meditate experience. And, from what we gather so far, the Buddha never said that “jhāna is a requirement for Nibbāna,” or that “Nibbāna is impossible without having reached one or all of the jhānas” (which would have been an important statements to say, at least a few times). So, is jhāna an absolute requirement to attain Nibbāna (and optionally, is it only reaching, masterering, one jhāna or all four)?
Note: If your answer is to be opinion-based, please post to point out things such as errors in deductive reasoning or basic logic, and to provide factual statements. Please try to include as many canonical references to support your statements.