Human quantitative ethics

Richard Parncutt 
March 2017

 rp

Quantitative ethics is an interesting combination of humanities and sciences.
Armchair reasoning has proven very successful in the history of philosophy. But quantitative methods have been equally successful, if not more so. So it makes sense to combine the two and get the best of both worlds. Unfortunately, surprisingly few do that.

Human quantiative ethics (HQE)

HQE is quantitative ethics in which the numbers in the tables and calculations refer to human lives. Consider the following example.

A country is discussing whether to build another nuclear reactor. Many are afraid of a future meltdown. In a worst-case scenario, a nuclear accident could cause the deaths of thousands of people plus thousands of birth defects in future children. The size of the risk depends on the probability of such a disaster, and there are in general different possible future scenarios to consider, each involving different probabilities and different estimated numbers of deaths. The question can be approached rationally and carefully by applying principles of risk assessment and multiplying the probability given scenarios with the number of deaths in each scenario. Of course the probabilities can only be estimated quite approximately, but experts generally agree whether a given probability is 10%, 1%, 0.1% or 0.01%. In this way, one might estimate the effective number of people that will die per year, on average, as a result of the reactor's operation. That might then be the basis for a public discussion about the number of lives one might reasonably risk in exchange for a reliable source of electricity for millions of people for a period of decades. 

It is possible in such cases that there will be never be a nuclear accident. The new reactor may never cause a single death or a single birth defect. That is the outcome that everyone wants, of course, but at the same time any responsible person will want to be informed of all possible outcomes and will want these to be systematically considered before deciding whether or not to go ahead with the project.

Climate change

Rational quantitative methods based on reasonable assumptions and estimates can allow us to estimate the probable future human impact of different global warming scenarios. We can estimate the number of future people who will probably die (that is, whose lives will probably be shortened) as an indirect result of the burning of fossil fuels today (calculator - model).

This is an important contribution to the climate debate that to my knowledge has been largely ignored or even suppressed. Perhaps most people are in denial about the human cost of climate change - even those who are quite clear about climate change itself and its human causes. Perhaps those in denial about the human costs of climate change include most climate scientists! The reader is asked to regard this statement as a scientific hypothesis rather than a criticism. I am interested in the extent to which such a claim could be correct. After all, climate scientists are only human and they have enough to worry about, without in addition considering how many humans might die in different warming scenarios.

HQE and human rights

HQE is based on human rights. There are two central premises.
It follows logically from these two premises that two human lives are twice as valuable as one. Therefore, if two human lives are threatened we should try twice as hard to save them. So far, so good.

HQE and the psychology of large numbers

But what happens when the numbers get much bigger? Is a catastophe involving a million deaths a million times worse than an accident in which one person dies?

We don't perceive a million lives (or deaths) as a million times more important than one life (or death), because our ability to empathize is limited. It is almost beyond us to empathize with just one dying person. First, their suffering may be greater than any suffering we have experienced ourselves. Second, there is something about death that we may never understand. What happens to our consciousness or "soul" after we die? Humans have been speculating about that for as long as they could be called humans, and even today we are no closer to a solution - except that many of us have at least had the courage to recognize (or assume) that there are some questions that we will never be able to answer, and that is one of them.

Every day we read in the media about accidents, conflicts or catastrophes in different parts of the world in which large numbers of people die. If we let these stories affect us the way they should, we could not function in our daily lives. Somehow, we have to filter out most of this information and only respond emotionally to only some of it. Sometimes a story about the fate or suffering of just one person reaches many more people emotionally than a story about the suffering of thousands. People often find it easier to empathize with an individual than with many people.

How bad, exactly, does a catastrophe with million deaths seem to us by comparison to just one death? It is possible to do a psychology experiment to answer that question. Without going into detail, we can anticipate the outcome. The ratio in this case is evidently much less than a million to one - at least in our experience and imagination. Perhaps it is the square root? Do a million deaths seem a thousand times worse than one death? If that were the case, a million deaths would seem a hundred times worse than a hundred deaths, and ten times worse than ten thousand deaths. When making claims like this, we are engaging in HQE.

Obviously, the estimates in the previous paragraph are very approximate. The consideration of very approximate estimates is characteristic of HQE. The idea is that it is often better to make some kind of calculation than none at all. In fact, the results of approximate calculations can often be very revealing. They can guide important ethical decisions. I will argue that we need calculations of this kind to help us make the most important decisions of all - decisions that could mean life and death for milllions of people.

Order-of-magnitude estimates

Approximate calculations play an important role in physics. Sometimes, they only involve powers of ten. In the example in the previous paragraph, a million is 106 and a thousand is 103. So we might claim that 106 deaths seem 103  worse than 100 deaths. In this example, we are concerned to get the exponents about right; we assume the the first exponent is 6 rather than 5 or 7, and the second is 3 rather than 4 or 2. This may seem overly approximate, but physicists often find this way of thinking very useful, for example when considering enormous versus tiny distances. The size of the universe  is about 1027 m and the Planck length is about 10-35 m. Don't worry about increasing the accuracy of such numbers before digesting the exponents!

HQE uses order-of-magnitude estimates to get a feel for the real human consequences of future catastophes such as a nuclear war or dangerous climate change. It is a way of getting beyond human subjectivity, which as we have seen cannot handle enormous numbers of deaths. Instead the aims is to treat every person as equally valuable, and respond to future threats accordingly.

The importance of HQE

Needless to say humanity is not very good as considering the future human costs of future actions. In the foreseeable future, the result of this failure may be the biggest catastophe that humanity has ever experienced - if not human extinction. HQE can help us to get a grip on this problem. We should be focusing a lot of expert effort into this fledgling academic discipline and not ignoring it as if our children did not exist or did not matter.
The opinions expressed on this page are the author's personal opinions.
Suggestions for improving or extending the content are welcome (parncutt at gmx dot at).
Back to Richard Parncutt's homepage