Does evolution legitimate Social Darwinism?

One of the biggest ethical dilemmas which I think is brought up by the theory of evolution is the notion that it may be morally justifiable to kill off the weak members of our society, if it helps us our species to survive. Could it be argued that evolution justifies this? And how should we respond?

Short answer, no. Natural selection does not always kill off the weak (whatever that is supposed to mean) members of a population.

It has definitely been argued that evolution justifies eugenics – Kent Hovind had a whole seminar that covered the supposed connection between evolution and different forms of genocide (Holocaust, massacre of Australian Aborigines, etc.).

I’m not sure the most coherent response, but certainly humans have killed off those they deemed “weak” long before anyone knew of the theory of evolution – even the Bible has been used to justify some pretty awful things. I’d have to know more about both the history of “social Darwinism” and the theory of evolution to give more specific critiques. I wonder whether BioLogos has covered this topic – probably, but I don’t see any search results for “social darwinism” or “eugenics.”

I assume you mean “argued with even a scrap of credibility.” Easy answer: nope.

By supporting higher-quality secondary education for all. The error of logic here is basic enough that a teenager should know how to avoid it.


That would be the Naturalistic fallacy. Just because something is natural does not mean it is morally good. You might as well argue that the Germ Theory of Disease is justification for not treating infections and letting patients die. The other popular analogy is Social Newtonism, where we throw people off of buildings because Newton’s Laws says they should fall.

Evolution describes the trends of outcomes when organisms compete for limited resources, and the theory also helps us understand what has happened in the past. Nowhere in the theory does it tell us what we ought to do. It simply tells us how nature operates in specific conditions.


First of all, the answer is that Natural Selection has been used to justify eugenics and Social Darwinism, so the answer to can it be used is Yes,

Second, Can it be legitimately used in this way? That depends. If we go by the definition of Natural Selection as Survival of the Fittest, Darwin and Co. did then again the answer is yes. Here the use is generally not killing people, but preventing them from reproducing.
One could object that a positive end does not justify an evil means

Third, I think that Darwin got Natural Selection wrong. It is not Survival of the Fittest, but Flourishing of the Better Adapted. Natural Selection does not need any help and it is wrong to do so. Nature is basically good. We need to learn from nature to improve its goodness.

When we blindly pollute the environment and encourage climate change we challenge the goodness of God’s creation and risk our own survival.

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That’s a good distinction – in the earlier parts of the last century it was more about forced sterilization in order to prevent “bad genetics” from getting passed on – but it really had more to do with classism and racism than science – “science” was just an excuse to keep the lower classes down.

Evolutionary theory is a descriptive model. It has nothing to say about how things “should be” just how things were/are and are likely to be. People who misguidedly use descriptive concepts from evolutionary theory to support eugenics or other social engineering projects are imposing their misguided values and social ideals on a description of nature. It should be obvious that human sociology and culture does not operate according to all the same processes that guide adaptation and reproduction in animal populations.


Why is the answer “yes”? Where in Darwin’s definition does it say that we should not allow humans to reproduce if we deem them less fit?

Exactly, its the old description vs prescription discussion.


Aren’t there some species in which weaker males are physically threatened so they won’t try to copulate with the females? Just playing devil’s advocate here. It would still be the naturalistic fallacy.

Sure. Competition between males for the rights to fertile females is common in many species. If we carry this analogy forward, then people should be arguing for polygamy since we see many species where polygamy is the norm, and it appears to be norm for our closest ape relatives. It would be interesting to see what people thought of making human society work like bonobo society, if they are indeed arguing that what is natural dictates human morality and behavior.

It is also interesting to see people take up both sides of the argument. One moment they are saying that we shouldn’t act like animals, and the next they are trying to argue that we should act in such a way because that is what animals do (i.e. that is how nature works).

Here are some related threads we should consider, if there is actual interest in the question above.

Does Newtonian physics legitimate the flattening of people with steamrollers?
Does toxicology legitimate the addition of arsenic to clam chowder? Maybe just once, please?
Does embryology legitimate abortion?
Does parasitology legitimate the installation of nutrient-sucking tubes in the intestines of poor people?
Does the study of Marburg virus legitimate its weaponization?
Is secondary education this bad all over the Western world?

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I agree with you. The thing is that we humans value things like social well being, equality and human dignity, so these things end up being placed higher than our evolutionary impulses or the overall fitness of our species. It should be noted though that many eugenists were more concerned with tribalism rather than actual human fitness, since mixigenation actually has a positive effect on fitness in many cases (the so called hybrid vigor), and the supposed scientific justification was really just a excuse for irrational prejudice.

The question I was trying to raise is that humans very well could be better off genetically if those with genetic defects were killed. (not my view at all)

Maybe, but we value other things above genetic fitness. I do know some people who do genetic counseling for couples, though, which is non-cohersive and therefore more ethical.

Fun fact, I do know lots of people who advocate for these things based on animal behavior (I study in a very liberal university). But they do so for ideological reasons, not academic, hahaha

Exactly. What people deemed less fit was not necessarily what nature deemed less fit which defeats the whole argument from the get go. On top of that, if natural selection is real then there is nothing we really need to do. The less fit will naturally have fewer offspring without us interfering. Eugenics is almost the admission that natural selection isn’t happening, so we have to step in and do the selecting ourselves.

An argument can also be made for keeping as much genetic variation in the population as possible. Those with alleles we deem less fit may also have alleles that are superior to other alleles. There is also the possibility that alleles which are currently detrimental could acquire another mutation in the future that is the foundation of a new and fitter phenotype, or interact with mutations in another gene that results in superior fitness.

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But that has nothing to do with whether such culling is morally legitimate. Nothing whatsoever. This is such a basic logical exercise.