Sometimes it is restricted to a particular episode and is based on evidence accumulated after the fact: Yes, the Soviet economic system was hugely inefficient; yes, the Obama fiscal stimulus of 2009 did reduce unemployment.
A veces, se limita a un caso particular y se basa en evidencia obtenida después del hecho: sí, el sistema económico soviético era enormemente ineficiente; claro, el plan de estímulo fiscal de Obama en 2009 redujo el desempleo.