Why positional case system

Question

mi tavla fi la lojban

The fi does not carry meanings. If we can have something like prepositions we can do this:

mi tavla [in] la lojban

mi tavla [to] do

(Words yet to be made are wrapped [like this]).

I feel that meaning-based prepositions are easier to remember.

Answer

fi is a preposition. Whereas English uses some kind of metaphorical system to describe arguments of a verb Lojban defines them in an order.

E.g.

• in English we say I talk of you
• in Spanish we say pienso en ti (literally I think in you !)
• in Russian we say Я думаю о тебе (literally I think about you).

These metaphorical prepositions are not universal across languages.

Thus Lojban is made neutral.

However, some prepositions are like what you just proposed. We have sumtcita (prepositions) with fixed meanings and positional ones too. So instead of

tavla fo la lojban

you can say

tavla bau la lojban

• mudri: I consider this a straw man argument. It is possible to have case systems with a much tighter fit to thematic roles than the European metaphorical system. As far as I understand, Ithkuil does this, and it seems far less arbitrary than the examples above. Also, it is possible to mimic a positional case system in a semantic case system by requiring explicit FA usage, so the semantic framework is strictly more powerful than the positional framework (and thus can be just as neutral). I find it useful for relations with multiple objects, where I just label them “obj0”, “obj1” &c.