Weinberg on QFT: Demonstrative induction and underdetermination

In this essay I examine a recent argument by Steven Weinberg that seeks to establish local quantum field theory as the only type of quantum theory in accord with the relevent evidence and satisfying two basic physical princip les. I reconstruct the argument as a demonstrative induction and indicate i t's role as a foil to the underdetermination argument in the debate over sc ientific realism.