„Efficiency" is the mirific concept on which basis it seems that almost all economists have ever built their judgements and theories. The way the efficiency's arguments are applied explains a lot of bad things that happens nowadays. This essay aims to emphasize the fact that „the efficiency criteria" entails insurmountable scientific limits. Ignoring them, either of unawareness or of special interest, easily leads to grave scientific errors. „Efficiency" is responsible for „legitimating" the public policy, increasing state power and politicizing economic science.