Morality and objective human nature

Some people (including some I know — you know who you are) believe that there are no objective natures, since all species are continually evolving. Human beings are not the same today as they were 2,000 years ago, and won’t be the same in another 2,000 years as they are today. This belief has profound implications for morality.

To begin with, if there is no objective universal human nature, there can be no definition of “man” which applies to all “men”. That being the case, how can there be a general prohibition against, for example, murder? “Murder” is “the deliberate killing of an innocent human being”. But if we don’t know what a “human being” is, how can we say it’s wrong to kill one? Or if it’s wrong to kill one, maybe it’s not wrong to kill another whose nature may differ from that of the first.

“Human being” or “man” traditionally has been defined as “rational animal”. But that really means “animal which is rational by nature“. Thus it includes human beings who are not currently capable of rational thought, such as infants or adults who may be in comas. By virtue of possessing human nature these still qualify as “rational animals”.

But if you remove “by nature” from the definition, then it only refers to people who are capable of rational thought at the present moment. Therefore babies in the womb, or out of it, as well as Alzheimer’s patients, are fair game; the former because they haven’t yet reached rationality, the latter because they’ve lost it.

Further, if people are continually evolving, then people in different places must evolve differently. The way evolution works in practice (as I understand it) is that creatures evolve in response to specific local conditions such as weather, the presence of predators, availability of food sources, etc. Therefore human beings would not evolve uniformly worldwide.  People living in different places and circumstances would evolve at different rates and in different ways.

How then can we say that “all men are equal”? There are two problems with this: First, as noted, if there is no objective universal human nature then it’s unclear who is included in the phrase “all men”. Second, if we evolve according to local circumstances, then it’s not necessary to believe that people from different places are equal. Some might have physical abilities, or for that matter rational ones, that others do not. (This doesn’t mean the more rational ones are evolutionarily more “advanced”, since if evolution is unguided then for all we know people might evolve to become less rational over time.)

Morality based on natural law also becomes unworkable since in natural law, the question of what men may and may not do is based on what is good according to the natures of things. If there is no universal human nature, then my nature is different from yours. Therefore, the good of my nature differs from the good of yours.

It seems, then, that if there is no objective universal human nature, morality becomes a subjective, ad hoc affair, to be determined on the spot. Based on what criteria I couldn’t say.

[This post was inspired, in part, by a recorded lecture by Fr. Brian Mullady, O.P. The parts I get wrong, of course, are my fault.]


4 thoughts on “Morality and objective human nature

  1. I believe that all species are continually evolving and that mankind is not the same today as 2000 years ago and will not be the same in 2000. However, it doesn’t follow that there is no universal human nature. In fact, the gospel requires us to believe in it and not just for the reason you describe. If God became Man to save a class of beings (we’ll call the class humanity) then either the constituents of that class were arbitrarily selected or else they have some coherent common class characteristic that justifies their inclusion in that class (we’ll call that common class characteristic universal human nature). However, the constituency of the class can’t be arbitrary, because otherwise God could not have become a Man, or at least there would be no meaning or significance to it. Imagine that I arbitrarily create the class Fizzlestick. Belonging to that class are (1) the state of being worried, (2) lots of cucumbers, and (3) the broken dreams of the middle class. Now I assign myself to that class. I also am a Fizzlestick! Yay! But the essential meaninglessness of the exercise is apparent. Because the Incarnation is meaningful, being a man must be meaningful and there must be a meaningful class definition.


  2. I’m not sure whether we’re disagreeing or not. In re-reading my post and your comment, I realized that I left out some background. The statement “Some people … believe that there are no objective natures, since all species are continually evolving”, is based on the premise that belief in continual evolution is incompatible with belief in the objective natures of things.

    If a thing is not the same today as it was 2000 years ago, and won’t be the same in another 2000, then how can you be sure that whatever we have evolved into in 2000 years will be of the same nature as those whom Jesus Christ died to save, which were was then known as “mankind”? I don’t think it’s so simple to say that the men of Jesus’ time were men, and men today are men, and the men of 2000 years from now will be men, all in the same sense, without equivocation, given the premise of continual evolution.

    It’s true that Christ died to save all men. But how then is “man” defined? If we are continually evolving, may we not eventually evolve into something that is no longer man?

    Perhaps you maintain that there is some kernel of our nature that will remain the same in us as it was in the men of Jesus’ time — i.e. something that is not subject to evolution — and that is the thing that makes us all “men” despite whatever changes may take place due to our continual evolution. Is that your position?

    If so, then that kernel would be the “universal human nature” or the “meaningful class definition”. In which case my position still stands: Continual evolution is incompatible with the existence of an objective, universal human nature.


  3. I doubt the men will evolve to cease to be men. But its theoretically possible, and if so it doesn’t defeat the truth of universal human nature or “the kernel.” My argument would be as follows: suppose I had a house that I kept on modifying, making it more and more barn-like. At some point it would no longer be a house, it would be a barn. But that doesn’t mean that ‘barn’ and ‘house’ are meaningless and arbitrary categories or that there is no such thing as house nature (i.e., universal characteristics of what it means to be a house).

    I wasn’t sure if we were disagreeing, but now that I see that we are.
    Take the proposition
    “there are no objective natures, since all species are continually evolving.” We both disagree with it. It can be disaggregated into the following argument.
    1. If all species continually evolve, there is no objective natures of species.
    2. All species continually evolve.

    You think 1 is right and 2 is wrong. I think 1 is wrong and 2 is probably right.


  4. Just to clarify how this started out: An online friend of mine said he didn’t believe in such things as the objective natures of things, since all things are constantly evolving. My post was to draw out what that belief would imply for morality: Since God’s moral commands are directed at men, if there is no objective human nature then you can’t define the set of beings to whom the commandments apply. It’s even more obvious that you can’t derive moral requirements in the form of the natural law, if there are no objective natures. Morality therefore would be ad hoc and subjective.

    I happen to agree with my friend that if species are constantly evolving, then they can’t be said to have fixed natures, by which I mean a definite nature which all men may be said to share. This appears self-evident: If a thing has a fixed nature, then its nature is not changing; and if it’s changing, then it’s not fixed.

    If the species doesn’t have a fixed nature, then it’s impossible that all men of all times and places could share the same nature, and therefore it’s not a universal nature.

    In fact, if there is no fixed, universal human nature, then my preceding sentence is unintelligible: You can’t speak of all “men” of all times and places if they don’t share a common, universal nature, since in that case some of “them” would be “men”, i.e. beings of the nature “human”, and some of “them”, possessing natures other than the nature “human”, would not.

    I look forward to you showing me where I’ve gone off the track here. : )


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