In this book the author maintains that fertility declines independently of its background.
Normally fertility decline is thought to occur as a result of alteration in the socioeconomic
background such as the decline of the infant mortality rate urbanization the level of
literacy and so on. This point of view has been regarded as equivalent to demographic
transition. However the concept of demographic transition is so superficial naïve and
unscientific that it should be applied merely to the ostensible demographic phenomena not to
the mechanisms of fertility decline. The author regards this way of thinking i.e. that the
occurrence of fertility decline is dependent on socioeconomic background as the background
dependence of fertility decline. On the contrary there is considerable counterevidence to the
background dependence of fertility decline. The argument is made that background dependence
lacks positive evidence and predictability and consequently is falsifiable. That decisive
counterevidence is introduced in this book. The author revives the diffusion hypothesis of
fertility decline at the point of the number of children per couple as the reaction-diffusion
process in a mathematical equation. Fertility decline in Europe in the eighteenth and
nineteenth centuries occurred as a reaction-diffusion process independent of socioeconomic
background. In Japan as well fertility (the number of children per couple) declined
independently of background. This book provides ample evidences persuasively demonstrating this
independence of fertility in Japan. The occurrence of marriage is also independent of
socioeconomic background. Thus the author formalizes the marriage function as an integral
equation of marriage probability as a result it demonstrates a better fit with the observed
data than does any other marriage function. Occurrence of marriage is almost solely dependent
on the density of marriages that occur in a given subspace.
