Without intelligence, either one's own or another's, true life is impossible.Source
either ones own or another's is the same as "whether one's own or another's?
In this context, "whether" would have the same effect as "either." In both cases, the message would be that the statement is true if applied to one's own intelligence, and is also true if applied to another's intelligence.
We would not, however, use "whether or" as an answer to a question of options, as we sometimes do with "either or." For example, if asked: "Do you want the yellow one or the blue one," if you do not care which color you get, you could respond "either or." This is not the case with "whether or."