Questions are beginning to bubble up - a good sign!
Developmental psychology really isn't my forte, so I'd like to toss the following questions out for your consideration.
In the reading I've been doing, I have often encountered the idea that there is no way of subjecting Freud's theory of personality development to scientific testing. I can see this. To perform the appropriate series of experiments it would be necessary to study a control population (eg. one where potty training is a relaxed, timely affair) with populations where the variable under examination is manipulated by the experimenter (eg. early, strict potty training and in a third population a complete failure to potty train). Any ethics committee worth its salt would object to the kind of study where the end result might be an individual suffering from a crippling neurosis.
But it seems to me that it might be possible to find a relatively homogenous culture where potty training is done early and then carry out a longitudinal study on these individuals, measuring their 'anality' at regular intervals over a twenty year period. This could be compared with a culture less concerned with early anal mastery. After all, even though longitudinal studies are an epic undertaking, they have been done. They're a useful tool in the developmental psychologist's goody bag.
Why aren't accusations of untestability levelled at other developmental theories? Is it because they don't claim to be making a strong causal link, whereas Freud did make such a claim?
Am I being hopelessly naive?