Why is social science so late to the science party?

Our ancestors thousands of years ago knew that if they really wanted to understand the heavens, they would have to sit down and carefully count some things.  By a few centuries ago, such painstaking efforts had yielded an impressive understanding of dozens of other subjects.  By the twentieth century, the virtues of counting to understand would seem to have long been established.

Ordinary people are far more interested in the social world around them than they are in most of the arcane topics to which counting was first applied.  And yet, social science didn’t really start to count in ernest until the twentieth century.  Why?  Here are some possible theories:

1. We thought we already understood the social world as well as we needed.
2. Social science is just very hard – simple counting yields far fewer
   useful insights than in other fields.  So social counting had to wait
   until we could do it on a massive scale.
3. The subject was taboo because we thought that a better social science would mainly just let some people take more advantage of others – there were few net benefits.
4. We held strong opinions on social topics, but at some level knew many of them to be false.  Social science was taboo for fear of confronting our self-deceptions about the social world.

I lean toward #4.  Comments are open.