The emergence of human consciousness remains a relatively enigmatic thing to many people, including me. Evolutionary Psychology seeks to understand the mind and human behavior by looking at psychology through the lens of evolutionary biology. The theory indicates that our minds and the various aspects of their function developed over time through the process of Natural Selection. Inference to the Best Explanation is a valuable method for critically evaluating evidence, and can be employed in an attempt to answer this question. Inference to the Best Explanation is a way of knowing that is distinct from Induction (pure observation), Deduction (pure logic), or Faith (religious conviction). By specifying all of the relevant evidence for a given claim, and then ranking other potential conclusions against it, a tentative determination can be made as to whether the original claim, or an alternative, is the best explanation for the evidence. For the purposes of this article I am going to use Inference to the Best Explanation to answer the question, “Is Evolutionary Psychology the Best Explanation for My Behavior?”
Before leaping into the arguments for Evolutionary Psychology, it makes sense to first evaluate the evidence for biological evolution, which stems from Charles Darwin’s complementary theories of Descent with Modification and Natural Selection. Common Descent with Modification is the idea that all life originated from a single ancestor, implying that I am an extremely distant relative to the intrepid spider that lives above my front door. Natural Selection is the driver of Descent with Modification, and the process by which the spider and I ended up so different. In his book, Origin of Species, Darwin provides abundant evidence for the theories of common descent and Natural Selection. I have summarized his evidence in schematic form:
E1: There is an extremely old Earth.
E2: The fossil record illustrates the various kinships between species.
E3: Natural classification systems also demonstrate linking branches.
E4: Species are adapted to their environments.
E5: Different species have striking similarities in morphology.
E6: Many species have indistinguishable embryo development.
T0: The explanation is therefore Descent with Modification.
In addition to the arguments for common descent, Darwin provided further evidence to demonstrate that Natural Selection was the way in which Descent with Modification is accomplished:
E1 - E6.
E7: Controlled breeding demonstrates artificial selection.
E8: Numerous extinctions have been revealed by the fossil record.
E9: Populations of animals are stable despite the potential for exponential growth.
T’0: There is a struggle to survive in nature.
E10: Beneficial traits that aid in survival are more likely to be passed to offspring.
T’’0: Therefore a Natural Selection of species takes place.
T’’’0: This leads to the gradual appearance of new species through aggregated changes.
Darwin’s theories have not gone unchallenged, and regardless of the continued accumulation of supporting evidence for the last 150 years, there are alternative explanations that purport to be better suited to the same facts. Evolution’s most vocals opponents are Intelligent Design Theorists and Creationists. The latter group essentially believes in the literal Creation story as laid out in the Book of Genesis. Intelligent Design claims that there is evidence for the existence of a Creator, suggesting that the clues to the intentional design of life are found in features that are irreducibly complex, such as the eye. This theory is often accused of being Creationism in disguise, but Intelligent Design proponents make many concessions that Creationists don’t. For instance, they accept the old age of the Earth and although they reject macro-evolution they agree with micro-evolution and certain aspects of genetics. Based on the evidence provided by Darwin (not to mention subsequent data not discussed here), I must rank it above these two rivals:
T0: Darwin’s Theories of Common Descent with Modification and Natural Selection
T1: Intelligent Design Theory
Evolutionary Psychology (Cosmides, Tooby) recognizes that the same process facilitating Descent with Modification must also be taken into account when attempting to understand the workings of the mind. The cognitive functions humans display today were shaped by the process of Natural Selection, implying that they contributed to our survival in some way. For a better understanding of any psychological domain, there are five principles offered by Evolutionary Psychology. Number one, the brain is like a computer that was designed to respond with the proper behavior for a particular setting. Secondly, the circumstances that our minds are best accustomed to dealing with are those which were dealt with by our ancestors. The third principle is to recognize that most of the cognitive processing related to behavior is happening below the radar of conscious awareness with the help of complex neural circuits. In fact, the fourth principle suggests that different brain circuitry developed to focus on different dilemmas through adaptation. The fifth principle is that our minds are still honed towards behaviors needed for survival in the hunter-gatherer environment of the Stone Age.
In order to demonstrate whether a particular type of cognitive process is the result of the Natural Selection due to its impartation of a survival benefit, one must discover “design evidence” (Cosmides, Tooby). Indentifying correspondences between the form and function is necessary for the support of Evolutionary Psychology. For my purposes the general arguments for Common Descent and Natural Selection are assumed as the base for expressing additional evidence in my schema, which tests the theory that the mind was developed evolutionarily. I have summarized the arguments for Evolutionary Psychology below:
E1 - E10.
E11: Studies in Primatology and Paleoanthropology have revealed that humans have possessed social dispositions for millions of years (Cosmides, Tooby).
E12: “Social contract algorithms” have been observed. Tests have shown that 25% of subjects are unable to detect violations of if-then reasoning in non-social situations, but the same methods of reasoning work 75% of the time when the subjects must detect cheating in social situations. (Cosmides, Tooby).
E13: The Somatic Marker Hypothesis suggests that our more primitive and automatic emotional responses to various scenarios are essential to higher order reasoning, including the proper behavior in social situations (Damasio).
T’’’’0: Psychological traits derive from the survival benefits they provided to early humans.
An alternative, and more traditional view of the mind within psychology, has been referred to as the Standard Social Science Model (Cosmides, Tooby). This approach assumes that the mind is a “blank slate” waiting for the experiences of perception to upload various human behavioral programs, like language and cultural norms. Evolutionary aspects of the mind are assumed here as well, but only in the sense that human minds have hereditary functions like learning and reason. However, it is from outside stimulus that we substantively derive our thoughts and feelings in the standard view. In addition to this alternative scientific model, there is also a wholly different explanation of human consciousness offered by Mind/Body Dualism. For the Dualist our minds are the non-corporeal Souls that although connected to our bodies are nevertheless made of an entirely different kind of substance altogether, which is by definition not physical. Richard Swinburne is an example of a Philosopher who completely subscribes to Darwin’s theories regarding evolution, yet argues passionately and effectively for Dualism and the existence of a Soul. Considering these rivals, I have ranked them in the order of likelihood given the evidence:
T0: Evolutionary Psychology
T1: The Standard Social Science Model
T2: Mind/Body Dualism
Dualism is last in my ranking because it does not offer a sufficient explanation for how an insubstantial mind is able to maintain a two-way causal relationship with the physical body, and yet be empirically undetectable. The Standard Social Science Model also fails to achieve the same explanatory power as Evolutionary Psychology. The evidence is best suited to the explanation that human social behavior was molded by Natural Selection. The strongest argument for this, in my opinion, is the original case presented for evolution in general. Cognition, being essential to humanity, was a product of our ancestor’s environmental pressures. Additional design evidence just makes the case that much more compelling.
Although I have reached a tentative conclusion that human cognition and behavior is grounded in evolution, it does not mean that I think that evidence itself can necessarily precludes the existence of a Soul, a Creator, or an Intelligent Designer. My conclusion is agnostic to these possibilities to a certain extent, because I am applying a method of reasoning that requires a logical handling of the available physical evidence and the theoretical rivals for explaining that evidence, and the rankings I chose reflect these rules. However, my interest in this topic stem from my conviction that a significant mystery still surrounds the phenomenon of human consciousness, and the existence of anything at all for that matter. Inference to the Best Explanation is a great method of knowing that allows one to apply evidenced based rules to reasoning, but it never completely rules conclusions out since it must by definition limit conclusions to the available evidence for and against them. Ways of knowing that are not evidence based, such as Faith, may lead one to a different conclusion.
Jared Roy Endicott
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Damasio, Antonio. Descartes’ Error. New York: Penguin Books, 1994.
Cosmides, Leda, and John Tooby. “Evolutionary Psychology: A Primer.” Center For Evolutionary Psychology. 13 January 1997. 6 July 2009.
Darwin, Charles. The Origin of Species. New York: Bantam Books, 1859.
Swinburne, Richard. The Evolution of the Soul. New York: Oxford University Press, 1986 (Revised Edition 1997).