Substantial vs. substantive
When I first heard someone use the word ‘substantive’ to mean ‘substantial’ three or four years ago, I assumed that they’d made a mistake. The next few times, which were in political speeches or academic contexts, I assumed it was pedantry or affectation. Now I hear it so much, that I’ve been forced (by my Chambers) to admit that it is probably a reasonable substitute.
Is there any substantial/substantive difference in the way one should use either form? And is there an explanation for the rise (if I am correct in perceiving it as a rise) in the use of ‘substantive’ over ‘substantial’?