A model of capital accumulation is built in relation with fertility and
consumption. Avoiding to impose a direct analytical relationship between these
three variables, the author studies the set of possible evolutions under the constraints
imposed by the inertia of habit change.
The conflict between the necessity to avoid impoverishment, the desire to increase
consumption when possible and the reproduction intensity delineate the set
of viable solutions and the set of attitudes leading to capital extinction. This
qualitative view of change of behaviors provides an alternative explanation to
historical fertility fluctuations outside the usual Easterlin framework.