This is Part 2 in a 3 part series on evolutionary theories of cognition. This part discusses Alvin Plantinga’s Argument from Proper Function. Part 1 examined C.S. Lewis’ Argument from Reason and part 3 will cover Plantinga’s Evolutionary Argument Against Naturalism. See Part 1 of this article here.
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.
(continued in Part 3)
28. Alvin Plantinga, Warrant and Proper Function (New York: Oxford University Press, 1993), 194. Warrant is not the same as justification (in the sense of epistemic duty; a duty to ensure your beliefs are true). Plantinga gives the example of a person with no political experience who develops a brain lesion that (inculpably) leads to the belief that this individual will be the next President of the United States. The belief appears even more obvious than the basics of elementary arithmetic and accordingly, out of duty to act in accordance with truth (or at least what the person sincerely and strongly believes to be the truth), this person behaves as if preparing for the presidency and develops all sorts of subsidiary beliefs about what is going to happen. While these beliefs clearly arise out of a noble allegiance to epistemic duty, they have little if no warrant behind them. Alvin Plantinga, Warrant: The Current Debate (New York: Oxford University Press, 1993), 44.↩
29. From (4) and (5) via the law of syllogism.↩
30. This is the assumption Plantinga contends both naturalists and super-naturalists must share.↩
31. From (6) and (7) via the law of detachment.↩
32. From the argument in (4) through (8).↩
33. From (9), (10) and (11).↩
34. Plantinga, Warrant and Proper Function, 196.↩
35. Plantinga, Warrant and Proper Function, 195.↩
36. Plantinga, Warrant and Proper Function, 197.↩
37. Plantinga, Warrant and Proper Function, 197.↩
38. Plantinga, Warrant and Proper Function, 198.↩
39. John L. Pollack, “How to Build a Person: The Physical Basis for Mentality,” Philosophical Perspectives 1 (1987): 149-50.↩
40. Plantinga, Warrant and Proper Function, 201.↩
41. John Bigelow and Robert Pargetter, “Functions,” The Journal of Philosophy 84, no. 4 (April, 1987): 192.↩
42. Bigelow and Pargetter, “Functions,” 192-93.↩
43. Plantinga, Warrant and Proper Function, 207.↩