Hans Stegeman (Triodos Bank) defended his doctoral thesis today at the Erasmus Universiteit Rotterdam (with Derk Loorbach as promotor). With Hans being an outspoken ‘transition-minded’ economist, we at DRIFT followed his PhD journey with much interest. So below we’re publishing his press release and forward you to the publication itself.
Rotterdam, 13 June 2025 – Sustainability must form the core of economic theory and policy, rather than being an afterthought. This is the argument made by economist Hans Stegeman in his dissertation ‘Transforming Economics for Sustainability’, which he defends today at Rotterdam School of Management, Erasmus University. As long as sustainability does not form the core of economic theory and policy, attempts at creating sustainable change remain superficial, fragmented and ultimately ineffective. “If you keep looking through old worldviews, you never make the transition to a new economy. And if you don’t do that, the end of our current economic system is inevitable. It will collapse.”
According to Stegeman, economic theory has historically developed as a response to the problems of its time. In the post-World War II period, the emphasis was on material scarcity and reconstruction – hence the focus on growth, productivity and efficiency. But many of those assumptions have since solidified into economic orthodoxy, even though today’s challenges – climate change, biodiversity loss, structural inequality – are fundamentally different. “We still treat environmental damage and social inequality as external factors,” states Stegeman. “But if we take sustainability seriously, that must be our starting point.”
The central question Stegeman addresses in his dissertation is: how can we integrate sustainability – defined as the condition of a system that maintains itself both ecologically and socially continuously and indefinitely – into economic theory, policy and practice? Stegeman identifies five key insights:
1. There is no single form of wellbeing – What people need to live well varies by situation. Ecological recovery requires something different than social connection. Policymakers must therefore better examine which type of wellbeing should be central in a particular domain.
2. Systems are interconnected and limited – Economic, ecological and social systems are interdependent. Economic activities often directly impact the environment, while social systems determine how people interact with their surroundings. When one system reaches certain limits, it can negatively affect other systems. For example, climate change (an ecological problem) can lead to food shortages (an economic and social problem).
3. We must abandon the idea that adding up all personal choices gives a good picture of what is good for society as a whole – The collective interest may even conflict with individual preferences. This is precisely where social relationships and institutions play a crucial role.
4. Worldviews shape institutions – What is seen as ‘realistic’ policy is often based on prevailing mindsets rather than actual necessity.
5. Gradual improvement is not enough – and often stems from old thinking. For major problems like climate change or biodiversity loss, we often think we can improve step by step. But this idea – that we can get by with minor adjustments – comes from a worldview where systems are stable and growth naturally leads to solutions. In reality, many systems work with tipping points: if we react too late, the whole system collapses.
Based on these insights, Stegeman makes several policy recommendations. He advocates for thorough adaptation of macroeconomic models, with ecological boundaries and social foundations at their centre. Fiscal and financial instruments should focus on promoting long-term public value rather than short-term efficiency. Additionally, we need new forms of collaboration where different groups can participate in decision-making. Sustainability should no longer be seen as a brake on the economy, but as the foundation for a new form of economic progress.
Editor’s note: Hans Stegeman is Chief Economist and Group Director Impact & Economics at Triodos Bank. He combines academic reflection with years of experience as an economist, including at CPB Netherlands Bureau for Economic Policy Analysis and Rabobank. His dissertation was written at Rotterdam School of Management, Erasmus University under the supervision of Prof. Dr. Dirk Schoenmaker and Prof. Dr. Derk Loorbach.
