Childhood and Madness: Modern Inventions?

The other day I came across something rather interesting.  I learned that a number of people had propounded a theory that certain realities we take for granted, did not in fact exist in years past.  For example, these people argued that in the ancient and medieval world childhood did not exist, and neither did madness.  Their justification for this is that the connotations which we associate with "childhood" and "madness" and all the ways in which we think of that are so different than they were in the past, that they have only recently come into existence.  For these people, calling ancient behavior that we would describe as "madness" is somewhat like calling an abacus "the calculator of the ancient world."  This sort of appellation does not work, because a calculator is so much different than an abacus and in many ways, and both carry different connotations.

However, it would seem that these people are suggesting the realities of childhood and madness themselves changed.  But is that possible? Why do we associate what the medieval world saw as "foolishness" with our current notion of "madness"?  It would appear that there is a fundamental reality upon which these notions are based.  Rather, it is the perceptions of and reactions to, childhood and madness that have changed.  The traditions and customs in regard to these two things have differed throughout the ages.  Yes, childhood did not exist in the ancient world, as we think of it today.  However, that does not mean that there were no children.  True, those who were considered to be mad were not shut up in an asylum during the Middle Ages.  But that does not exclude the fact that people did lose their wits.

There was a similar question in the 13th century, which queried whether or not things that we gave the same name had anything truly in common besides their appellation.  Why do we call each individual wooden, leafy thing with branches a tree? As it turns out, each of these trees has a common nature.  It is separated by designated matter, but still shares the same properties as other trees.  There is an objective reality which is shared by all trees, and all men, every squirrel and so on.
Now apply this same principle to the previous issue.  Why do we call something madness, or childhood, though it viewed quite differently in separate eras? There must be some objective reality which is seen by each age.  Yes, societies change, and so do the reactions to many realities.  But the realities are still there.

So no, childhood and madness are not different things in different eras.  They are certainly treated differently, but the objective reality is the same.  There has to be something to be treated differently.