Mere addition paradox

Mere addition paradox

The mere addition paradox is a problem in ethics, identified by Derek Parfit, and appearing in his book, Reasons and Persons (1984). The paradox identifies apparent inconsistency between three seemingly true beliefs about population ethics by arguing that utilitarianism leads to an apparent overpopulated dystopian world.


The Paradox

The paradox arises from consideration of four different possibilities. The following diagrams show different situations, with each bar representing a population. The group's size is represented by column width, and the group's happiness represented by column height. For simplicity, in each group of people represented, everyone in the group has exactly the same level of happiness, though Parfit did not consider this essential to the argument.


In situation A, everyone is happy.

In situation A+, there are the extra people. There is the same population as in A, and another population of the same size, which is less happy, but whose lives are nevertheless worth living. The two populations are entirely separate, that is, they cannot communicate and are not even aware of each other. Parfit gives the example of A+ being a possible state of the world before the Atlantic was crossed, and says that A, in that case, represents an alternative history in which the Americas had never been inhabited by any humans.

In situation B-, there are again two separate populations, of the same size as before, but now of equal happiness. The increase in happiness of the right-hand population is greater than the decrease in happiness of the left-hand population. Therefore, average happiness in B- is higher.

Finally in situation B, there is a single population whose size is the sum of the two populations in situation B-, and at the same level of happiness.

Going from A to B

The difference between the situations A and A+ is only in the existence of extra people at a lower level of happiness. If the two populations were known to each other, and were aware of the inequality, this would arguably constitute social injustice. However, as they do not, Parfit says this represents a Mere Addition, and it seems implausible to him that it would be worse for the extra people to exist. Thus, he argues, A+ is not worse than A.

Furthermore, there are the same numbers of people on both sides of the divide in situation B- as there are in situation A+. The average happiness in B- is higher than A+ (though lower than A). Since A+ and B- have the same number of people, and because there is a greater level of equality and average happiness in B-, it seems that, all things considered, B- is better than A+. But the situations B- and B are the same, except the communication gap is removed. It seems that B is at least as good as B-.

The Repugnant Conclusion


We can then repeat the argument, and imagine another divide, and ask if it would be better for more extra people to exist, unknown to the people in B, and so on, as before. We then arrive at a situation C, in which the population is even larger, and less happy, though still with lives worth living. And if we agree that B is not worse than A, then we would conclude in the same fashion that C is not worse than B. But then we could repeat that argument again, finally arriving at a situation Z, in which there are an enormous number of people whose lives are worth living, but just barely. Parfit calls this the Repugnant Conclusion, and says that Z is in fact worse than A, and that it goes against what he believes about overpopulation to say otherwise. This is a contradiction, but it is not clear how to avoid it.

Criticisms and responses

The paradox is immediately resolved by the conclusion that the "better than" relation is not transitive, meaning that our assertion that B- is better than A by way of A+ is not justified—it could very well be the case that B- is better than A+, and A+ is better than A, and yet A is better than B-. This is of course incompatible with any form of utilitarianism. Temkin argues for this approach.

The paradox can be defeated by asserting that A+ is actually worse than A, in other words, that adding people of less-than-average happiness into the world makes the overall situation worse. This is the conclusion of "average utilitarianism", which aims at maximizing average happiness. However, this solution may commit one to the position that it is actually bad for people of less than average happiness to be born, even if their lives are worth living.

Another position might argue for some threshold above the level at which lives become worth living, but below which additional lives would nonetheless make the situation worse. Parfit argues that for this position to be plausible, such a threshold would be so low as to apply only to lives that are "gravely deficient" and which, "though worth living ... must be crimped and mean." Parfit calls this hypothetical threshold the "bad level," and argues that its existence would not resolve the paradox because population A would still be better than an enormous population with all members having lives at the "bad level."

Parfit also considers an objection where the comparison between A+ and B- is attacked. The comparison between A and A+ was partly dependent on their separation. Thus A+ and B- might simply be incomparable. Parfit gives the Rich and Poor example, in which two people live in separate societies, and are unknown to each other, but are both known to you, and you have to make a choice between helping one or the other. Thus, despite their separation, it is meaningful to ask whether A+ is better than B- or not. One could deny that B- is better than A+, and therefore neither is B. But this rejection implies that what is most important is the happiness of the happiest people, and commits one to the view that a smaller decrease in the happiness of the happiest people outweighs a bigger increase in the happiness of less happy people, at least in some cases. Parfit calls this the Elitist view.

Of course one can simply accept the Repugnant Conclusion. Torbjörn Tännsjö argues that we have a false intuition of the moral weight of billions upon billions of lives "barely worth living". He argues that we must consider that life in Z would not be terrible, and that in our actual world, most lives are actually not far above, and often fall below, the level of "not worth living". Therefore the Repugnant Conclusion really isn't so repugnant.

See also

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Twin paradox — In physics, the twin paradox is a thought experiment in special relativity, in which a twin makes a journey into space in a high speed rocket and returns home to find he has aged less than his identical twin who stayed on Earth. This result… …   Wikipedia

  • Average and total utilitarianism — All proponents of utilitarianism believe that the quality of conscious experience is important; indeed it is the basis of their consequentialist approach to ethics. However, it is unclear what it is that is supposed to be maximized: average… …   Wikipedia

  • Utilitarianism — This article discusses utilitarian ethical theory. For a discussion of John Stuart Mill s book Utilitarianism, see Utilitarianism (book). For the architectural theory, see Utilitarianism (architecture) Part of a series on …   Wikipedia

  • List of paradoxes — This is a list of paradoxes, grouped thematically. Note that many of the listed paradoxes have a clear resolution see Quine s Classification of Paradoxes.Logical, non mathematical* Paradox of entailment: Inconsistent premises always make an… …   Wikipedia

  • Список парадоксов — …   Википедия

  • List of philosophy topics (I-Q) — II and thou I Ching I Ching I proposition I Thou I Thou relationshipIaIamblichus (philosopher)IbYahya Ibn Adi Yahya Ibn Adi Ibn al Arabi Muhyi al Din Ibn al Arabi Abu Bakr Ibn Bajja Abu Bakr Ibn Bājja Abu Bakr Muhammad Ibn Yahya Ibn as Say igh… …   Wikipedia

  • Suffering — This article is about suffering or pain in the broadest sense. For physical pain, see Pain. For other uses, see The Suffering. Tragic mask on the façade of the Royal Dramatic Theatre in Stockholm Suffering, or pain in a broad sense,[1] is …   Wikipedia

  • Utility — This article is about the economic concept. For other uses, see Utility (disambiguation). Part of a series on Utilitarianism …   Wikipedia

  • Social choice theory — is a theoretical framework for measuring individual interests, values, or welfares as an aggregate towards collective decision. A non theoretical example of a collective decision is passing a set of laws under a constitution. Social choice theory …   Wikipedia

  • David Hume — For other people named David Hume, see David Hume (disambiguation). David Hume David Hume Born 7 May 1711(1711 05 07) Edinburgh, Scotland Died 25 August 1776( …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.