We propose an adaptation of Hartwick's investment rule to models with population growth and show that following Hartwick's rule is equivalent to a time-invariant real per capita net national product. In the so-called DHSS model of capital accumulation and resource depletion the proposed...

This paper uses fractional integration methods to measure the degree of persistence in historical annual data on the world population over the period 1800-2016. The analysis is carried out for the original series, and also for its log transformation and its growth rate. The results indicate that...

I distinguish two types of macroeconomic models. The first type are top-down models in which some or all agents are capable of understanding the whole picture and use this superior information to determine their optimal plans. The second type are bottom-up models in which all agents experience...

Predator-prey relationships account for an important part of all interactions between species. In this paper we provide a microfoundation for such predator-prey relations in a food chain. Basic entities of our analysis are representative organisms of species modelled similar to economic...

In this paper we develop a micro ecosystem model whose basic entities are representative organisms which behave as if maximizing their net offspring under constraints. Net offspring is increasing in prey biomass intake, declining in the loss of own biomass to predators and Allee's Law applies....

The weak rationality principle is not an empirical statement but a heuristic rule of how to proceed in social sciences. It is a necessary ingredient of any ‘understanding’ social science in the Weberian sense. In this paper, first this principle and its role in economic theorizing is...

Although the relationship between natural resources and civil war has received much attention, little is known about the underlying mechanisms. Controversies and contradictions in the stylized facts persist because resource extraction is treated as exogenous while in reality fighting affects...