minor spoilers for InuYasha season 6:
Only the dead may pass these gates. We make sure all those who wish to pass are dead. —The gate guardians
we can view this activity as making an implicit model true (enough). the model is that "everyone beyond these gates is dead." the guardians make it true by "making sure all those who wish to pass are dead." (also, there is no other way in... with an asterisk.)
see: parable of the pebbles. like counting, this model "works only because we make it work," though in this context we means the guardians.