The Future of Utilitarianism

My recent work has focused on the demands of utilitarianism, and our obligations to future people.¹ In my current work, I draw on that earlier work, and ask how utilitarians might deal with the ethical challenges of climate change.² Climate change has obvious practical implications. It will kill millions of people, wipe out thousands of species, and so on. My question in this paper is much narrower. How might climate change impact on moral theory — and especially on the debate between utilitarians and their non-utilitarian rivals?

1. The Broken World

I am especially interested in the philosophical implications of the possibility that dangerous human-induced climate change may produce a broken world, where resources are insufficient to meet everyone's basic needs, where a chaotic climate makes life precarious, where each generation is worse-off than the last, and where our affluent way of life is no longer an option. This is not our world. Humanity currently has the resources to meet everyone's needs. But nor is the broken world merely imaginary. It is one possible future.

Everything about climate change is controversial in public debate. If the internet teaches us nothing else, it does remind us that every fact is denied by someone. So I want to stress the modesty of my empirical assumptions. I claim only that past and present human behaviour may produce something like a broken world at some point in the future. This modest claim is sufficient to motivate our discussion; and no-one can reasonably be confident that it is false

My current research project on ethics for a broken world has two dimensions. The first re-imagines ethics within a broken world. To make the thought experiment vivid, I imagine a history of philosophy class in the broken world, studying classic texts from a past age of affluence.³ This highlights the contingency of our moral and political ideals — as when we study past political philosophers in their historical context.

The second dimension of my project studies the impact of a broken future on us. If we consider only present people and their needs, then our world is not broken. But, on any plausible moral theory, the well-being of future people matters as much as our own. So the needs of 'our world' include the needs of future people, and 'our resources' include its future resources. If, on this wider definition, our resources are insufficient to meet all our needs, if we must choose between present and future needs, then our world is already broken.

This commitment to temporal impartiality is a striking feature of contemporary utilitarian moral philosophy. It is also very relevant to the public debate over climate change. As the scientific evidence that humans are causing climate change has become overwhelming, climate change 'sceptics' have shifted from science to economics. One very common sceptical argument is that the future benefit of preventing climate change is not worth the present cost. Central to this 'cost-benefit analysis' is a social discount rate, where future costs or benefits are discounted. Even a modest discount of 5% per annum makes it 'uneconomic' to spend even one dollar today to avert a global catastrophe in five hundred years time.⁴

Everyone agrees that it is reasonable to discount as a proxy for uncertainty, or to accommodate the remote possibility that there will be no future people. (Humanity might be wiped out by an asteroid strike, of instance.) It would also make ethical sense to discount if you reasonably believed that future people will be richer than present people. (Of course, this argument may be reversed if we accept the possibility of a broken future where people are worse-off than today.)

However, many economists go further, and apply a pure time preference. Future happiness counts for less simply because it lies in the future. This pure discounting is justified on the grounds that this is how people actually behave. We do discount future benefits, both to ourselves and to others.

While they may accept discounting for other reasons, utilitarian moral philosophers reject any pure time preference...