Another theory that comes up is that the earth is somehow the penalty box for celestial beings who have “fallen” from their celestial status and they have the opportunity, through their efforts here to regain their celestial status. Even if there is some factual basis behind this supposition, clearly this still demands a past that influences the present circumstances, and a process, spanning potentially multiple rebirths, for the being to work through the “issues”, as it is clear that one lifetime cannot and does not afford the celestial being the opportunity to solve the concerns so obviously visible when we look at the general “issues” with which humanity is burdened.
Sri Aurobindo explains his view on the matter: “But it is evident that this one earthly life is not sufficient for all to effect that difficult return, but rather most may and do miss it entirely; and we have then either to suppose that an immortal soul can perish or be doomed to eternal perdition or else that it has more existences than this poor precarious one apparently given to it, lives or states of being which intervene between its fall and the final working out of a sure redemption.”
There are of course additional difficulties with this theory, not the least of which is the reason why this descent is necessary for all of these higher beings. There is also the rationale behind the differing conditions under which each of these beings is then asked to respond. “Each must surely have had a past which made him responsible for his present conditions, if he is to be held thus strictly to account for all their results and the use he makes of his often too scanty, grudging and sometimes quite hopeless opportunity. The very nature of our humanity supposes a varying constituent past for the soul as well as a resultant future.”
We take away from this that whether the evolutionary process is completely of the earth, or involves souls moving between this and other worlds, there still is required a process and a mechanism for this soul evolution, and this therefore supports the process of rebirth and the working of karma.