Okay, I'll accept that it's a continuity, not two distinct populations. But let me clarify what I'm referring to as "drift".
Let's look at some small segment of the population with a certain amount of education. (If you like math, picture that we're looking at a distribution of population density on the y-axis and education on the x-axis, and looking at a small section of the population with a particular education we're looking a a small dx range.)
If I am understanding you and the idiocracy hypothesis correctly, you/it have postulated that there are two ways the population at this particular education level can change: birth (increases population) and death (decreases population). The premise is that birth rate outweighs death rate for people at a low level of education, and that death rate outweighs birth rate for people at a high level of education, resulting in a flow to the left (less education) on this graph.
I postulate that there are two other ways this population at a particular level of education can change: if people less educated than this segment gain more education (increases the population at this education level), and if people already in this segment gain more education (decreases the population at this education level). Because individual people can never lose education, this ability of individuals to change segments will result in a flow to the right (more education) of this graph.
So we have two competing effects: the hypothesized birth/death rate inequity that results in a flow to the left (less education), and the individual increase in education that results in a flow to the right (more education). In order for an idiocracy to take place (a net shift towards the left / less education), we need for the flow to the left to be greater than the flow to the right. I have seen no evidence that this is the case.
no subject
Let's look at some small segment of the population with a certain amount of education. (If you like math, picture that we're looking at a distribution of population density on the y-axis and education on the x-axis, and looking at a small section of the population with a particular education we're looking a a small dx range.)
If I am understanding you and the idiocracy hypothesis correctly, you/it have postulated that there are two ways the population at this particular education level can change: birth (increases population) and death (decreases population). The premise is that birth rate outweighs death rate for people at a low level of education, and that death rate outweighs birth rate for people at a high level of education, resulting in a flow to the left (less education) on this graph.
I postulate that there are two other ways this population at a particular level of education can change: if people less educated than this segment gain more education (increases the population at this education level), and if people already in this segment gain more education (decreases the population at this education level). Because individual people can never lose education, this ability of individuals to change segments will result in a flow to the right (more education) of this graph.
So we have two competing effects: the hypothesized birth/death rate inequity that results in a flow to the left (less education), and the individual increase in education that results in a flow to the right (more education). In order for an idiocracy to take place (a net shift towards the left / less education), we need for the flow to the left to be greater than the flow to the right. I have seen no evidence that this is the case.