How do social scientists define and measure causation?

What is a counterfactual? How does it help us understand nomothetic causality?

Some have suggested that the increase in global temperatures has been caused by the declining number of pirates on the high seas. On what basis might this claim be made? Why would social scientists be reluctant to accept it?

Why isn't all social research longitudinal?

Using the US Census as an example, explain the difference between unit of analysis and unit of observation.