This is the first of four installments in a blog series by Russell A. Barkley, Ph.D.  The full series is titled “Reason is a Type of Evolution (Universal Darwinism).”  Dr. Barkley will speak and lead a discussion for RRNA on January 30th, 6:30 p.m., at the Libbie Mill Library.  This series is not obligatory reading in order to attend, but it frames and supplements Dr. Barkley’s appearance.  The next three installments will be posted over the remaining days before the 30th.

What is Reason?  How is it Like Evolution?

by Russell A. Barkley, Ph.D.

What is Reason?  It is a process of thinking critically about our ideas and those of others.  Those ideas are pieces of information, usually about the natural world.  When we use Reason, we compare those ideas against the evidence that may be available to support or refute them.  In short, we criticize the information.  We determine the extent to which it agrees (conforms) or disagrees with the natural world and the information we have previously collected about it.  In this way, we let the environment and its evidence assist us in selecting out or refuting ideas or statements that do not agree with that evidence.

We are especially interested in evidence that can refute the idea, statement, or assertion about the world.  That is because our available evidence may be quite limited and so may not be able yet to refute an idea.  Strictly speaking, a lack of evidence for refuting an idea does not mean that the idea is definitively true or correct.  It means only that we await the collection of further evidence that could potentially refute, or falsify, the statement.  Until then, the statement may continue to be accepted as provisionally supported – we may continue to use it for the time being until more evidence for or against it becomes available.   We may stipulate to the degree of confidence we have in the idea’s truth-value given a substantial body of evidence that supports (doesn’t refute) it.  So the information or idea survives for now.  There is always the chance that a time may come later when evidence becomes available that may refute the idea. We remain skeptical about ideas and statements about the world, understanding that we may tentatively accept an idea as being true for now while awaiting further evidence, particularly when the available evidence may be very limited.

More specifically, Reason first involves making coherent and logical (noncontradictory) statements about some aspect of the natural world.  It then involves testing that idea and the information it contains against the prevailing relevant evidence from that natural world.  In some cases, the statement is really just a hypothesis – an educated guess about the nature of something.  In that case, we may do some further experimentation to determine if that statement can withstand the evidence provided by that experiment.  The experiment is designed in such a way as to test the assertion to see if it agrees or disagrees with the evidence from that experiment.

This does not have to involve formal scientific experimentation.  All of us test some of our ideas against the environment on a frequent if not daily basis.  For instance, when we face a problem, such as what may be wrong with an appliance that is not working.  We may initially propose an explanation.  We then go about testing that explanation or trying it out to see what happens.  We let the evidence from that test feed back to tell us if our initial idea was correct.  If it isn’t, we abandon it and propose another possible explanation and try that out.  Notice that when we engage in this type of personal experimentation, we are letting the environment and the evidence it is providing select out or refute our bad (false) ideas. It is as if we are playing 20 questions with the environment until we hit upon the correct solution (explanation).  The environment, through its criticism of the idea (negative feedback) is serving to shape or guide our attempts at finding a correct explanation by weeding out the ideas that are wrong.  This is like natural selection by consequences.

Making an assertion and testing it against the prevailing evidence is like a trial or replication in that evidence is being examined for and against the truth-value of the statement.  Such experimentation or testing of the idea is the essence of critical thinking, or Reasoning.  Ideas or assertions that can withstand such criticism and testing against reality survive to be accepted — they live on for awhile longer.  They may do so until further testing may serve to refute them (eliminate them) or at least modify portions of them.  The revised version can then be tested again. Note that these statements that seem to agree with the evidence are viewed as being only tentatively or provisionally true or correct.  We understand that they may be subsequently refuted by further evidence that is not yet available.  Science is based on Reasoning.  But it is a much more systematic, codified, and social or cultural means by which we use reasoning along with the more strict standards used for gathering scientific evidence to formulate and test statements about the natural world.  Reasoning is usually done personally or within our own mind, though we may share our reasoning with others.  In contrast, science is social.  It is done within a community of other scientists and the results are shared through a more formal process of journal publication involving peer review or at least presented at a scientific meeting of our peers during which our peers offer feedback.

Can Reason (and Science) be viewed as a type of evolution by natural selection (Darwinism)?  The answer, in my opinion, is “yes.”  People who are familiar with Darwinian evolution by natural selection nearly always understand it at the biological or genetic level, as in how species originate and evolve over time.  Far less well understood is that evolution by natural selection (henceforth simply termed evolution) can occur at other more psychological and sociological (cultural) levels by which information about the natural world is acquired.  Viewing evolution as a general process by which information about the world is tested against it is known as Universal Darwinism.  It states that the process of the evolution of all information about the natural world, not just genetically coded information, occurs through natural selection – the testing of the information against reality for its degree of agreement with the natural world.

Evolution is like an algorithm or set of steps.  Those specific steps can be found in Part II, the next article (blog) I have posted.  They do not concern us here.  What does is examining the similarities between the process of evolution as it is understood to operate at the genetic or biological level and Reason as it operates at the psychological and social level (as Science).

All of these forms of evolution involve coded information.  In the case of genetic evolution, it is the information coded in genes using the nucleic acids abbreviated by the letters A-G-T-C.  That information can be coded in a sequence of letters that is used to create proteins that build organisms from that information.  In the case of Reason, it is information encoded in the idea, statement or assertion that may be spoken or even written down.  In the case of Science, the information is published in scientific archives.

Both genetic evolution and Reason involve testing the information against the environment through trials or experiments.  In genetic evolution, this is done through repeated replications (reproduction) of the information and especially the organisms that genetic information produces.  In Reason it involves making an assertion and then testing that information against the environment.

In both biological evolution and Reason, the information is being tested against the surrounding environment for how well or poorly it may survive so as to reproduce itself again.  Biological or genetic evolution serves to test genetically coded information and the organism it creates for how well they agree with or conform to the environment.  The more that genetic information (and its vehicle – the organism) disagrees or conflicts with the environment, the more likely it is not to survive and so to reproduce again.

In both genetic evolution and in Reason, the environment is therefore criticizing the information offered up in the trial or experiment for how well it matches the relevant conditions in the natural world.  As Darwin argued, the environment is selecting out organisms (and the genetic information they contain) for how poorly that organism (and its information) matches up with that environment.  The more that information fails to match up with the environment, the less likely it is to survive (and so be destroyed) by the environment relative to other arrangements of that information that may be better adapted to (in better agreement with) that environment.  Others have argued that Reason and Science do much the same thing.  They serve to offer up information in such a way that it can be tested against the natural world and that world serves to select out or remove that information based on the feedback (evidence) so obtained.

In sum, evolution by natural selection is not limited simply to information coded in genes and DNA, or the genetic level.  More than 50 years ago, the renowned psychologist, Donald Campbell, argued that evolution is a general explanation for how information about the environment can accumulate over time and undergo continuous refinement (Campbell, 1960).  As he claimed, anywhere in the universe that information about the environment (knowledge) can be found to have accumulated it will have done so by a Darwinian process of evolution (replication with environmental selection).  Richards (1987) later supported this view.  The great philosopher, Karl Popper, also argued that knowledge about the world, such as that produced by science, develops by a process of natural selection – the testing of information against the natural world and having that information refuted.  As he argued, Science advances not so much by conformation as disconfirmation (criticism).

The similarities between Reason (and Science) and biological evolution are numerous.  They support the contention that Reason is just a special case of a universal process by which information about the environment is tested against that world and retained or eliminated by feedback from that testing (it is being naturally selected by the evidence).


Campbell, D. T. (1960). Blind variation and selective retention in creative thought as in other knowledge processes. Psychological Review 67: 380–400.

Popper, K. & Eccles, J. (1977).  The self and its brain.  Berlin/London: Springer-Verlag.

Richards, R. (1987).  Darwin and the emergence of evolutionary theories of mind and behavior.  Chicago, IL: University of Chicago Press.

This blog is an adaptation and updating of material from R. A. Barkley (2012). Executive Functions: What They Are, How They Work, and Why They Evolved.  New York: Guilford Press.  ©Guilford Press, 2012.  Adapted and reprinted with permission.

Dr. Barkley is a Clinical Professor of Psychiatry at the Virginia Commonwealth University Health Center and the Virginia Treatment Center for Children, Richmond, VA.