Even if this was true, I would like to point out that a good part of this debates is about the accuracy of the input data used for the math. With disputed input

Even if this was true, I would like to point out that a good part of this debates is about the accuracy of the input data used for the math. With disputed input data math is never simple just ask any data analyst around. Edit: Also this math involve predictions about demographics evolution over the next decades in a global warming and war in europe context. Both can result in unpredictable populations movements. This is never simple ask any demographer around. Edit2: What is complicated about politics especially in french strong state tradition is that laws reform are precisely meant to alter the input data of your model, often with unforeseen side effects, so it's not simple math ask any historian around. This especially worst in France because it's a known and widely discussed issue that the government is indirectly doctoring some key statistics like unemployment data. Changing the metric while you are rolling out a reform is at this point a patented french strategy to prevent any citizen to evaluate a new policy.