  We study the testable implications of models of dynamically inconsistent
choices when planned choices are unobservable, and thus only "on path" data is
available. First, we discuss the approach in Blow, Browning and Crawford
(2021), who characterize first-order rationalizability of the model of
quasi-hyperbolic discounting. We show that the first-order approach does not
guarantee rationalizability by means of the quasi-hyperbolic model. This
motivates consideration of an abstract model of intertemporal choice, under
which we provide a characterization of different behavioral models -- including
the naive and sophisticated paradigms of dynamically inconsistent choice.
