Does the implicit pension debt mean anything after all?

We discuss the meaning of the concept of implicit pension debt (unfunded pension liabilities) from a public finance perspective and contrast different definitions such a variable with the notion of public debt. We conclude that the implicit pension is deeply different from public debt but nevertheless is meaningful for economic policy. We compute the implicit pension debt associated to retired workers for several countries for different years adopting a homogeneous algorithm. Our results show that the major countries have implicit pension debt of very different size with different trends in the last few years.