18This limiting result requires that we impose the , because the perfect
foresight consumption function is not defined if
. Informally, the proof is as follows. Define
as the consumption function for the unemployed consumer who will receive no future
labor income. Then
, and so
. In the limit as
,
however, human wealth accounts for an arbitrarily small proportion
of consumption, so
so the precautionary motive captured by
vanishes.