As far as Lebowski lore goes, I'd say the nihilists play both sides of the free will issue. On the one hand, the nihilists are not really about aggression. They have no more interest in killing than they do in politics ("Say what you will about the tenets of national socialism, but at least it's an ethos!"). In this vein, they represent the Dude's stasis. Nothing matters, not even existing. The Dude and the Nihilists co-habitat the earth, caring nothing about the other.
But by a simple twist, the Dude shares a name with a person from whom the nihilists want to extort money. Even after they pee on his rug, Dude wants to bowl, not caring beyond a sort of distant dissatisfaction until his highly aggressive friend, Walter, takes an interest. Walter pushes him into a different world, where he becomes subject to things like aggression, motivation, and will.
Now the nihilists become enemies. They still believe in nothing ("Yah, we believe in nothing, Lebowski!") at this point--though this changes when one of them is forced to make a sacrifice (a toe)-- and the Dude suddenly becomes "deadbeat" Lebowski, a person trying to find meaning. Of course, his search comes up empty. No meaning is found, and the victim is zen-like Donny who never wavers from his non-aggressive nature.
And good old Maude, she's also an aggressor. Will the child become a creator? I'd say no, if only because the premise seems to disallow creation, or change. In fact, I'd guess the offspring will be zen-like and non-affectual, like poor Donny. Little Lebowski is conceived to bring balance to the force, so to speak.
The knowledge uncovered by the Dude's journey is piercing the illusion of free will. "You know, man. The Dude abides." I love that line, by the way. And the Townes van Zant (sp?) cover of the Stones' "Dead Flowers" is a brilliant choice, too, suggesting the results when someone tries to change the nature of life.
Oh, Dude.
TBT