It is said of the Sotāpanna that they will be reborn a maximum of 7 more times, either as a human or as a deva. I believe the highest deva realm they can go to are the gods of the 33. For a Sakadagami it is said they will be born once more as a human. To be born as a human or as a deva amongst the 33 is due to excellent virtue. That these realms are the limit for these individuals does tell us something. Neither of them will be reborn in the Brahma worlds or higher. This means that neither the Sotāpanna or Sakadagami has attained the 1st Jhāna or anything higher (formless). They are excelled in virtue, but not in concentration or wisdom. Now, this is fine if we accept that their Right Samādhi is something just short of Jhāna (let’s ignore the absorbed vs not-absorbed debates here). A problem arises however when we consider that those who awaken, either fully or not, are able to attain the Emptiness, Nothingness (sometimes put as Intentionless) and Signless concentrations. In the suttas these concentrations are only possible with a very high degree of equanimity. This is even more explicit in the Āneñjasappāya sutta (MN 106). The three problems I see then are:
How is it possible to have such a high degree of equanimity that one can attain the 3 concentrations, yet not pass through the 4th Jhāna?
How is it possible to have such a high degree of equanimity that one can attain the 3 concentrations, one of which at least is a formless attainment, yet if they die without being an Arahant they will never be born in the formless realms (despite MN 106 saying this is a possibility)?
A Sotāpanna & Sakadagami “know” or have “seen” nibbāna, yet both still have desires for sensual pleasures such as music, sex, food etc. How is this possible?