You're going to have to be more specific here. Which bit of logic are you referring to? Because it seems to me that the primary logic in my post (how one differentiates between interpretations) is expressly directed towards excluding biographical information from the decision-making process. If you couldn't follow my logic let me know where I lost you.
Are you referring to my statement "if he were to say the book is ABOUT Melville, then he is making a biographical statement about Tolkien's intent in writing the book"? If so, then I apologize for not making clear that I believe it is possible to talk about what a book says without making a statement of any kind about what the author may or may not have
tried to say. So it is possible to make statements about a book that are not biographical statements about the writer.
A statement of the type "This book is ABOUT such and such," is implying that the book has been
intended to illustrate such and such, which is a biographical statement. I'll happily admit that it's possible to use such words and not mean to imply anything biographical.
I can only refer you to the post you just quoted, particularly the bit where I said, "Some interpretations ARE better than others, but NOT because they more nearly match the author's intent. They are better either because they are better supported by the text, or they are more interesting, or both."
If that doesn't refute your notion that I'm saying all interpretations are equal, I don't really know what else I can do.
But for the sake of completeness (I know there's an unturned stone in here somewhere), I will say that I believe the notion that interpretations are either valid or invalid, correct or wrong is a bad way to proceed. Some interpretations are BETTER than others. They are not all equal. But that doesn't mean some are right and others are wrong. Some may be so much better than others that we accept them unquestioningly. Some may be so poorly supported, so uninteresting, that we reject them out of hand. If you want to call the former "right" and the latter "wrong", I won't stop you. But if you only consider interpretations that fall into one of those two categories, you're missing out on all the fun.
Now I'm confused. Are you on the side that thinks meaning is dependent on authorial intent or are you on the side that thinks the reader is free to come up with any meaning they like, regardless of what the author may have intended? Because this statement seems like a complete reversal of everything else you've said.
However, if you think I have proved that meaning is up to the reader, then I'll take my bow. Thank you. With the caveat that you may be free to come up with any interpretation you like, but that doesn't mean any interpretation you come up with will be as good as any other.
*bows*
*then notes Pielorhino calling him post-modern*
I'm a structuralist, darnit! Lump me in with a bunch of French intellectual posers, will you?
One of my favourite books on "pomo" thinking is
Against Deconstructionism, by John Ellis. Hope that helps elucidate my position.