Intergenerational Impartiality: Replacing Discounting by Probability Weighting

  • NG Yew-KwangEmail author


Intergenerational impartiality requires putting the welfare of future generations at par with that of our own. However, rational choice requires weighting all welfare values by the respective probabilities of realization. As the risk of non-survival of mankind is strictly positive for all time periods and as the probability of non-survival is cumulative, the probability weights operate like discount factors, though justified on a morally justifiable and completely different ground. Impartial intertemporal welfare maximization is acceptable, though the welfare of people in the very far future has lower effects as the probabilities of their existence are also lower. However, the effective discount rate on future welfare values (distinct from monetary values) justified on this ground is likely to be less than 0.1 per annum. Such discounting does not compromise environmental protection and sustainability unduly. The finiteness of our universe implies that the sum of our expected welfare to infinity remains finite, solving the paradox of having to compare different infinite values in optimal growth/conservation theories.


discounting environmental ethics impartiality intergenerational intertemporal probability sustainable development welfare 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Arrow, K. J 1964Aspects of the Theory of Risk-Bearing Yrjö Jahnsson LecturesYrjö Jahonssonin SäätioHelsinkiGoogle Scholar
  2. Beckerman, W. 1995“How Would You Like Your “Sustainability,” Sir? Weak or Strong? A Reply to My Critics”Environmental Values4169179Google Scholar
  3. Beekman, V 2004“Sustainable Development and Future Generations,”Journal of Agricultural and Environmental Ethics17322CrossRefGoogle Scholar
  4. Bergson (Burk), A 1938“A Reformulation of Certain Aspects of Welfare Economics,”Quarterly Journal of Economics52310334Google Scholar
  5. Blackorby, C, Bossert, W, Donaldson, D 1997“Critical-level Utilitarianism and the Population-Ethics Dilemma,”Economics and Philosophy13197230Google Scholar
  6. Blackorby, C, Donaldson, D 1984“Social Criteria for Evaluating Population Change,”Journal of Public Economics251333CrossRefGoogle Scholar
  7. Broome, J 1992Counting the Cost of Global WarmingWhite Horse PressLondonGoogle Scholar
  8. Carlson, E 1998“Mere addition and the two trilemmas of population ethics,”Economics and Philosophy14283306Google Scholar
  9. Chichilnisky, G., “An Axiomatic Approach to Sustainable Development,” Social Choice and Welfare 13 (1996), 231–257. Reprinted in G. Chichilnisky (ed.), Mathematical Economics. Vol 2 (Elgar Cheltenham, UK and Northampton, MA, 1998).Google Scholar
  10. Cline, W. R. 1992The Economics of Global WarmingInstitute for International EconomicsWashington, DCGoogle Scholar
  11. Dasgupta, P. 1995“Optimal Development and the Idea of Net National Product”Goldin, Winters,  eds. The Economics of Sustainable DevelopmentCambridge University PressCambridgeGoogle Scholar
  12. Doeleman, J. A 1980“On the Social Rate of Discount: The Case for Macroenvironmental Policy”Environmental Ethics24558Google Scholar
  13. Heal, G 1998“Interpreting Sustainability”Chichilnisky, GHeal, GVercelli, A eds. Sustainability: Dynamics and UncertaintyKluwer Academic PublishersDordrechtGoogle Scholar
  14. Kant, I., “Idea for a Universal History with a Cosmopolitan Purpose.” In Hans Reiss (ed.), (1970/1991), Political Writings (Cambridge U Press, Cambridge, 1979).Google Scholar
  15. Kemp, M. C., Ng, Y.-K. 1976“On the Existence of Social Welfare Functions, Social Orderings and Social Decision Functions”Economica435966Google Scholar
  16. Islam, S. M. N 2001“Ecology and Optimal Economic Growth”Munasinghe, MSunkel, OMiguel, C eds. The Sustainability of Long-term GrowthEdward Elgar CheltenhamUKGoogle Scholar
  17. Mirrelees, J. A., “Optimal Growth When Technology is Changing,” Review of Economic Studies 34 (1967).Google Scholar
  18. Mueller, D 1989Public Choice IICambridge University PressCambridgeGoogle Scholar
  19. Newell, R. G., Pizer, W. A. 2003“Discounting the Distant Future: How much do Uncertain Rates Increase Valuations?”Journal of Environmental Economics and Management465271CrossRefGoogle Scholar
  20. Ng, Y.-K. 1984“Expected Subjective utility: Is the Neumann-Morgenstern Utility the Same as the Neoclassical”s?”Social Choice and Welfare1177186CrossRefGoogle Scholar
  21. Ng, Y.-K. 1986“Social Criteria for Evaluating Population Change: An alternative to the Blackorby-Donaldson criterion”Journal of Public Economics29375381CrossRefPubMedGoogle Scholar
  22. Ng, Y.-K. 1989“What Should We Do about Future Generations? The impossibility of Parfit”s theory X”Economics and Philosophy5135253Google Scholar
  23. Ng, Y.-K. 1995“Towards Welfare Biology: Evolutionary Economics of Animal Consciousness and Suffering”Biology and Philosophy10255285CrossRefGoogle Scholar
  24. Ng, Y.-K. 2000Efficiency, Equality, and Public Policy: With a Case for Higher Public SpendingMacmillanBasingstoke, HampshireGoogle Scholar
  25. Ng, Y.-K. 2004“Sustainable Development: A Problem Environmental Disruption now instead of Intertemporal Ethics”Sustainable Development12150160CrossRefGoogle Scholar
  26. Ng, Y.-K., Liu, P. T 2003“Global Environmental Protection: Solving the International Public Goods Problem by Empowering the United Nations through cooperation with WTO”International Journal of Global Environmental Issues3409417CrossRefGoogle Scholar
  27. Ng, Y.-K. and I. Wills, “Welfare Economics and Sustainable Development.” In Knowledge for Sustainable Development – An Insight into the Encyclopedia of Life Support Systems, (UNESCO Publishing/Eolss Publishers, Paris, France, Oxford, UK, 2002), Vol. 3, 485–506.Google Scholar
  28. Parks, , Robert, P. 1976“An Impossibility Theorem for fixed Preferences: A Dictatorial Bergson-Samuelson Welfare Function”Review of Economic Studies43447450Google Scholar
  29. Peterson, E. W. 1993“Time Preference, the Environment and the Interests of Future Generations”Journal of Agricultural and Environmental Ethics6107126Google Scholar
  30. Pigou, A. C. 1929The Economics of WelfareMacmillanLondonGoogle Scholar
  31. Portney, P. R.Weyant, J. P. eds. 1999Discounting and Intergenerational EquityResources for the FutureWashington, DCGoogle Scholar
  32. Price, C. 1993Time, Discounting and ValueBlackwell PublishersOxfordGoogle Scholar
  33. Reiss, H. eds. 1970–1971Kant: Political WritingsCambridge University PressCambridgeGoogle Scholar
  34. Roberts, K. 1980“Social Choice Theory: The Single-Profile and Multi-Profile Approaches”Review of Economic Studies47441450Google Scholar
  35. Segerberg, K. 1976“A Neglected Family of Aggregation Problems in Ethics”Noûs10221244Google Scholar
  36. Sen, A. K. 1970Collective Choice and Social WelfareNorthHollandAmsterdamGoogle Scholar
  37. Spash, C. L. 1993“Economics, Ethics, and Long-Term Environmental Damages”Environmental Ethics15117132Google Scholar
  38. World Commission on Environment and Development1987Our Common FutureOxford University PressNew YorkGoogle Scholar
  39. Ramsey, F. P. 1928“A Mathematical Theory of Saving”Economic Journal38543559Google Scholar
  40. Vallentyne, P. and S. Kagan, “Infinite Value and Finitely Additive Value Theory,” Journal of PhilosophyXCIV (1997), 5–26.Google Scholar
  41. Weizsacker, C. C. V. 1965“Existence of Optimal Programs of Accumulation for an Infinite Time Horizon”Review of Economic Studies3285104Google Scholar
  42. Winkelmann, L., Winkelmann, R 1998“Why Are The Unemployed so Unhappy?”Economica65115CrossRefGoogle Scholar

Copyright information

© Springer 2005

Authors and Affiliations

  1. 1.Dept. of EconomicsMonash UniversityMelbourneAustralia

Personalised recommendations