Are these entirely interchangeable? Or is there sometimes reason to use one but not the other? (Other than, as one website says, to use 'eo ipso' rather than 'ipso facto' if you really want to be pretentious and obscure.)
Wiktionary says: 'eo ipso' = Through or by that very act or quality; thereby. 'ipso facto' = By that very fact itself.
I came across 'eo ipso' in this sentence:
It is one thing to say that I know what is good for X, while he himself does not; and even to ignore his wishes for its - and his - sake; and a very different one to say that he has eo ipso chosen it, not indeed consciously, not as he seems in everyday life, but in his role as a rational self which his empirical self may not know - the 'real' self which discerns the good, and cannot help choosing it once it is revealed.