Statistics on human rights violations are difficult to collect (perpetrators hide their actions and victims may be too ashamed or afraid to come forward), but they also matter, because they tell us which problems are the most severe and therefore deserve the most attention and funding. This situation gives human rights advocates incentives to inflate the numbers or choose the highest number when different estimates are available. Therefore it is important to check the estimates on a problem even when they are provided by well-meaning advocates.
BBC News does precisely that regarding “slavery” in the modern world. A recent estimate is there are 21 million slaves in the world today. BBC points out that the definition of slavery is different here than the definition used in the past – these slaves are not legally bought and sold, for instance. Moreover, the estimates about the global scale of the problem come from about a dozen surveys in different countries and then extrapolated from those countries to the whole world.
While recognizing that the numbers are very imprecise, we must not deny that the problem exists and that to understand the magnitude of the problem we have to start somewhere. As one researcher from the project says:
“We may be completely off the rails, I can’t deny that. When you are confronting a crisis and you are coming up with the best numbers you can, of course it’s right to put that number out there.”