Ten Minas Ministries

IS NATURALISM RATIONAL?

THE SELF-DEFEATING EPISTEMOLOGY BEHIND EVOLUTIONARY THEORIES OF COGNITION

            No matter how contentious an intellectual debate may appear, both parties agree on at least one thing.  They both assume that rationality, if properly used, leads to true conclusions.  The laws of identity, non-contradiction, and excluded middle, for example, accurately describe reality.[1]  If human perceptions about these basic truths were incorrect, then it would be impossible to reason to any conclusion.

            Theists argue that this necessary presupposition is incompatible with a naturalistic worldview.  If naturalism is true then rationality is not reliable, undercutting all beliefs including acceptance of naturalism itself.  Arguments of this genre are coined “arguments from reason.”

 

C.S. Lewis’ Argument from Reason

            C.S. Lewis advanced an argument from reason that can very generally be summarized as follows:

(1) If adherence to a worldview makes it impossible to believe that rational thinking is reliable, that worldview should be rejected.

(2) A naturalistic worldview makes it impossible to believe that rational thinking is reliable.

(3) Therefore, a naturalistic worldview should be rejected.[2]

            Premise (1) is uncontroversial.  “A theory which explained everything else in the whole universe but which made it impossible to believe that our thinking was valid, would be utterly out of court.  For that theory would itself have been reached by thinking, and if thinking is not valid that theory would, of course, be itself demolished.”[3]

            Premise (2) is the heart of Lewis’ argument which he supports with a sub-argument:

(2.1) Rational thinking is reliable only if it is based upon recognizing ground-consequent relationships.

(2.2) If two things are related by cause-effect, they are not also related by ground-consequent.

(2.3) According to naturalism, all phenomena are explained only on a cause-effect basis.

(2.4) The category of “all” phenomena includes rational thinking.

(2.5) Naturalism requires that rational thinking be based upon cause-effect relationships rather than ground-consequent relationships.[4]

(2.6) Therefore, a naturalistic worldview makes it impossible to believe that rational thinking is reliable.[5]

            Lewis’ argument hinges on his distinction between cause-effect and ground-consequent relationships.

We can say, ‘Grandfather is ill today because he ate lobster yesterday.’  We can also say, ‘Grandfather must be ill today because he hasn’t got up yet (and we know he is an invariably early riser when he is well).’  In the first sentence because indicates the relation of Cause and Effect: The eating made him ill.  In the second, it indicates the relation of what logicians call Ground and Consequent.  The old man’s late rising is not the cause of his disorder but the reason why we believe him to be disordered.[6]

 

Rationality depends upon premises being seen as grounds for a consequent conclusion (2.1).  But if “causes fully account for a belief, then, since causes work inevitably, the belief would have had to arise whether it had grounds or not” (2.2).[7]  If naturalism is true[8] “every event in Nature must be connected with previous events in the Cause and Effect relation” (2.3).[9]  Acts of thinking are “events in Nature” (2.4).  Therefore, according to naturalism they also must be explained by previous events on a cause-effect basis (2.5).[10]  The conclusion (2.6) therefore follows from (2.1) and (2.5).[11]

            Lewis’ argument has not been without its critics. Erik J. Wielenberg challenges Lewis’ premise that naturalism must explain rationality only on a cause-effect basis.[12]  He argues that because evolutionary theory predicts human reasoning will be incapable of explaining rationality, that outcome cannot be used as evidence against it. [13]

Weilenberg relies upon Colin McGinn’s “New Mysterianism.”  According to McGinn, human intelligence “is an evolutionary contrivance, designed with purposes far removed from the solution of profound philosophical problems, and it is not terribly surprising if it lacks the tools to crack every problem.”[14]  Weilenberg claims the theist uses this same approach to answer the problem of evil by arguing a finite human mind should not be expected to fully comprehend the infinite divine mind.[15]

Weilenberg’s parallel, though, fails.  The theistic argument against evil claims that strong non-propositional evidence for the existence of the theistic God overwhelms the evidence from evil against him.[16]  The alleged parallel is that non-propositional evidence for the existence of truth-guided rationality overwhelms the evidence from naturalism against it.  The naturalist’s version, though, unlike the theist’s, contains “a double presupposition.”  In claiming to believe that non-propositional evidence for accurate reasoning abilities counts as “evidence” at all, the naturalist must presuppose (1) that human belief-forming mechanisms are designed to promote the formation of accurate beliefs and (2) that these mechanisms do in fact generate true beliefs.  Only then is the naturalist justified in trusting a belief in the non-propositional evidence for reliable rationality.[17]  But “the reflective naturalist will doubt both of these”[18] because, as Lewis and Plantinga[19] illustrate, a naturalistic worldview cannot support the conclusion that rationality promotes true beliefs, including a belief in non-propositional evidence.[20]

            Some critics claim that creatures with reliable cognitive abilities hold a survival advantage over those whose reasoning is unreliable.  Therefore, over time natural selection will lead reliable faculties to predominate society.[21]

First, “some creatures are able to survive and procreate without any beliefs whatsoever.  What is required for survival is effective response to the environment, not accurate knowledge of that environment.”[22]

            Second, the “mere presence of survival value does not guarantee that we really have a naturalistic explanation on our hands.  The item possessing the survival value must be physically realizable.”[23]  Lewis never claimed natural selection could not promote the survival of accurate reasoning abilities once they existed but rather that naturalism has no way to account for their coming into being initially.[24]

Third, even if inaccurate rationality was wholly unfavorable toward survival, natural selection would not necessarily weed it out.  The same gene may influence both a favorable and an unfavorable trait.[25]  The unfavorable trait survives despite its disadvantages because it is “linked” to a more advantageous one.  Even if accurate reasoning abilities promote survival (and human cognitive abilities have proven over time to be favored by natural selection), that does not mean those abilities are reliable. Inaccurate abilities may have survived because they were linked to something more advantageous.

In response to Lewis, John Beversluis claims the act of drawing an inference is not a form of knowledge.  Logical rules are true without any need for further justification as to why they are true.[26]

First, Beversluis is clearly mistaken that drawing an inference is not an act of knowing.  When people reason “If p then q, p, therefore q,” they are not simply stating that it will hold true in the particular case before them.  Rather they believe that this inference (modus ponens) will hold true in the future as well and in all possible worlds.  This is clearly “knowledge” of reality.

Second, Beversluis confuses ontology with epistemology.  He is correct that modus ponens is ontologically true without any need for further explanation.  However, the key question is how people may know it to be true.  That is a matter of epistemology.  If naturalism is true, all events are the result of preceding efficient causes.  The mental act of knowing modus ponens to be true in this and all possible worlds is no different.[27]

           

Alvin Plantinga’s Argument from Proper Function

            Alvin Plantinga advances two separate arguments against Naturalism that bear some resemblance to Lewis’.  Like Lewis, Plantinga’s argument from proper function begins with a necessary assumption about cognitive abilities.  Whereas Lewis assumes the reliability of rationality, Plantinga presupposes a standard of “proper functioning.”

            Not all beliefs can be logically proven.  Any syllogism must begin with premises. If a skeptic questions the truth of a premise, a new syllogism may be formulated to support it.  But the premises of this new syllogism may be similarly challenged, as could those of any subsequent argument, ad infinitum.  Eventually, some premise (or premises) must be presupposed in order for logical reasoning to begin.

Not all presuppositions are equal.  According to Plantinga, some beliefs have “warrant,” even if they cannot be affirmatively proven.  Warranted beliefs can serve as starting presuppositions.  A belief B can have warrant for an individual if and only if

(1) the cognitive faculties involved in the production of B are functioning properly… ; (2) your cognitive environment is sufficiently similar to the one for which your cognitive faculties are designed; (3) the triple of the design plan governing the production of the belief in question involves, as purpose or function, the production of true beliefs … ; and (4) the design plan is a good one: that is, there is a high statistical or objective probability that a belief produced in accordance with the relevant segment of the design plan in that sort of environment is true.[28]

 

Plantinga’s definition of “warrant” assumes that human cognitive faculties have a “proper function.”  From this he constructs his argument against naturalism:

(4)  If organisms have a proper function, they must have a design plan.

(5) If organisms have a design plan, they must have been designed by a rational being.

(6) Thus, if organisms have a proper function, they must have been designed by a rational being.[29]

(7)  Organisms have a proper function.[30]

(8) Therefore, organisms must have been designed by a rational being.[31]

            Plantinga demonstrates how this reasoning renders naturalism inconsistent:

(9) Naturalism requires the belief that organisms have a proper function.

(10) A belief in the proper function of organisms logically requires the belief that they were designed by a rational being.[32]

(11) Naturalism also includes the belief that nothing was designed by a rational being.

(12) Any worldview that is logically required to hold contradictory beliefs should be rejected.

(13) Naturalism is logically required to hold contradictory beliefs. [33]

(14) Therefore, naturalism should be rejected.

            To assert that someone’s mental faculties are not functioning properly is to imply the existence of a standard of “proper function” by which all functions are measured.  This is not limited to cognitive abilities.  It equally applies to physical organs.

We think a hawk’s heart that beats only twenty-five time a minute is not functioning properly, that AIDS damages the immune system and makes it function poorly, that multiple sclerosis causes the immune system to malfunction in such a way that white blood cells attack the nervous system, and that the purpose or function of the heart is to pump blood, not to make that thumpa-thumpa sound… thinking in these terms is natural and apparently unavoidable for human beings.[34]

 

The difficulty arises when people attempt to define the “proper” function of an organism as opposed to an artifact.[35]  An artifact (such as a clock) is functioning properly when it is functioning as its creator (the clockmaker) intended.  From a theistic worldview an organism is similarly functioning properly when it is functioning as its creator (God) intended.[36]  However, from a naturalistic perspective there is no intelligent “creator” to whom to refer for proper function.

Most “of the disciplines falling under biology, psychology, sociology, economics, and the like … essentially involve the notions of proper function, damage, malfunction, purpose, design plan, and others of that family.”[37]  So the concept of “proper function” is critical to a naturalist.  According to Plantinga, the notion of an organism having a proper function assumes the existence of a design plan.  But the existence of a design plan also appears to require a rational being to create the plan.[38]  Plantinga, like Lewis, concludes that naturalism is inconsistent with its own necessary presuppositions.

Several criticisms have been launched against Plantinga’s argument, all of which commit equivocation, using “function” to mean one thing when applied to artifacts but something else entirely when referring to organisms.  Only theism provides a consistent definition.

For example, John L. Pollack proposes that (when applied to an organism) proper function is the way something “normally works;” i.e., the statistically most probable manner for it to function.[39]  However, merely acting contrary to the majority does not make a function improper.

The vast majority of sperm don’t manage to fertilize an egg; the lucky few that do can’t properly be accused of failure to function properly, on the grounds that they do things not done by their colleagues.  Most baby turtles never reach adulthood; those that do are not on that account dysfunctional.[40]

 

Obviously, statistical predominance cannot define proper function.

            John Bigelow and Robert Pargetter suggest that the proper function of a character within an organism is the propensity of that character to instill a survival advantage within an otherwise healthy system.[41]  If another organ within an interconnected system malfunctions such that the character in question no longer promotes survival, it is still functioning properly because “it would enhance survival if the other organs were performing as they do in healthy individuals.”[42]

Bigelow and Pargetter’s argument is circular.  The proper functioning of any one element of a system is defined in terms of the proper functioning of the remaining elements of the system.  However, whether those elements are functioning properly depends on the proper functioning of all other elements, including the original element under consideration.

Bigelow and Pargetter also “overlook systems or organs whose function is damage control or repair (healing, for example) or troubleshooting; these systems properly come into play only when there is loss of proper or healthful function elsewhere.”[43]  The “natural habitat” for these systems would be when they are surrounded by unhealthy organs.

 

Alvin Plantinga’s Evolutionary Argument Against Naturalism

            Plantinga also formulated an “Evolutionary Argument Against Naturalism” as follows:

(15) If both naturalism and evolution are true, then human cognitive faculties are the result of blind mechanisms such as natural selection.[44]

(16) Natural selection selects for survival-related behaviors, not necessarily true beliefs (except to the extent belief is “appropriately related to behavior”).[45]

(17) If evolutionary naturalism is true, then the primary function of human cognitive abilities is to promote survival-related behaviors, not necessarily the production of true beliefs.[46]

(18) Given that it is not natural selection’s primary function, the probability of evolutionary naturalism producing cognitive faculties that lead to true beliefs is low or inscrutable.[47]

(19) One of the allegedly true beliefs held by the naturalist is a belief in metaphysical naturalism itself.[48]

(20) Therefore, “the devotee of [evolutionary naturalism] has a defeater for any belief he holds, and a stronger defeater for [evolutionary naturalism] itself.”[49]

            Plantinga’s second argument has more in common with Lewis than his first.  While they take slightly different paths, both arguments demonstrate that if human cognitive reasoning is the result of evolutionary naturalism, it cannot be trusted to yield truth.  Because of their commonalities, similar objections are advanced to both.

            One such objection is launched at (16) and (17).  Plantinga and Lewis both assume an either/or proposition; i.e., either natural selection favors survival or it favors truth. Critics claim that the two go hand in hand, with the generation of true beliefs promoting survival and fitness.[50]  Plantinga responds by explaining that the probability of an evolutionary process producing true beliefs is low or inscrutable.

            Survival depends upon behavior, not beliefs.  An organism can believe that something will promote its survival, but unless it actually behaves in an adaptive manner it will not survive.  The criticism, therefore, is only sound if true beliefs lead to adaptive behavior.  Plantinga lays out five possibilities:

(i) There may be no connection between beliefs and behavior.[51]

(ii) Beliefs may be the effects, rather than the cause of behavior.[52]

(iii) Beliefs may be causally related to behavior via their syntax, not their content (as someone’s voice may break glass due to the sound itself, not the words being sung).[53]

(iv) Beliefs may be causally related to behavior both syntactically and semantically, but maladaptive.[54]

(v) Beliefs may be causally related to behavior and adaptive.[55]

The last possibility is that advanced by naturalists. On any of the other four, natural selection would not necessarily produce true beliefs.   Even under (v) it is still improbable that beliefs are true.  This is because beliefs do not

causally produce behavior by themselves; it is beliefs, desires, and other things that do so together.  Suppose we oversimplify a bit and say that my behavior is a causal product of just my beliefs and desires.  Then the problem is that clearly there will be any number of different patterns of belief and desire that would issue in the same action; and among those there will be many in which the beliefs are wildly false.[56]

 

Taking into account all possibilities, the probability of evolution producing an accurate belief forming mechanism is low or inscrutable.

            In response, William Alston suggests that even if belief in evolutionary naturalism casts doubt upon reliable rationality, the great deal of basic warrant enjoyed by the latter will vastly outweigh any defeating tendency of the former. [57]  But Alston misconstrues the nature of a defeater.  Defeaterhood “has to do with what the design plan requires, once you acquire a new belief; it does not have to do with the rationality, for you, of this new belief.”[58]  There is no calculus of warrants.  If you hold belief a (regardless of whether a itself is rational), it becomes irrational for you to simultaneously hold belief b if one of the entailments of a is that b is not true.

[G]iven that I believe that my head is made of glass, what changes in my noetic structure are required by proper function?  Well, one thing that will occur (if the defeater system is functioning properly), is that I will no longer believe that my head is made of flesh and bone.[59]

 

Similarly, given that a person believes in evolutionary naturalism, the entailments of that belief invalidate any acceptance of reliable rationality.[60]  Relative “weights” are irrelevant.  The issue is one of internal consistency within a worldview.[61]

 

Conclusion

Naturalistic phenomena are related to each other only on a cause-effect basis.  Human reasoning abilities must have a “proper function.”  The survival-related behaviors preferred by natural selection are unlikely to be associated with true belief forming mechanisms.  As C.S. Lewis and Alvin Plantinga demonstrate, any of these factors, when taken to their logical conclusion, demonstrate the irrationality of a worldview based upon evolutionary naturalism.