http://forum.rpg.net/showthread.php?617555-Paging-shanoxlit-What-would-a-Lojban-speaking-culture-look-like&p=17810171#post17810171
For those of you who can not access the link, here is the discussion:
Lojban is not a logic in the sense that logicians use the word. It has the syntax but not the semantics. A logic needs both. See the Semantics section of the wiki page of first-order logic for a brief overview on what first-order semantics look like. I have not seen any Lojban documents that would have defined the structure that's used for interpreting the words of the language, a class of structures that would provide acceptable interpretations, or even a rule for constructing such classes of structures.
Could you provide an example of one word that has semantics defined for it in the logical sense? Every word that I've seen has been defined in terms of translations to other languages with possibly a sentence or two explaining which of the different meanings of the word is intended. Those are not first-order definitions of things.