  This article traces the origins of Kenneth Wilson's conception of effective
field theories (EFTs) in the 1960s. I argue that what really made the
difference in Wilson's path to his first prototype of EFT are his long-standing
pragmatic aspirations and methodological commitments. Wilson's primary interest
was to work on mathematically interesting physical problems and he thought that
progress could be made by treating them as if they could be analyzed in
principle by a sufficiently powerful computer. The first point explains why he
had no qualms about twisting the structure of field theories; the second why he
divided the state-space of a toy model field theory into continuous slices by
following a standard divide-and-conquer algorithmic strategy instead of working
directly with a fully discretized and finite theory. I also show how Wilson's
prototype bears the mark of these aspirations and commitments and clear up a
few striking ironies along the way.
