Why Don’t People Think Evolution Is True? Implications for Teaching, In and Out of the Classroom

Insufficient/Incorrect Factual Knowledge

The hypothesis that non-acceptance of a particular scientific conclusion, theory, or idea is mainly due to insufficient knowledge is intuitively appealing, especially to educators, who usually view their job to be communication and explication of such conclusions, theories, and ideas. Some level of familiarity with empirical “facts” is obviously required for rational acceptance of any idea about the material world (e.g., if you don’t know that the Second World War came before the Vietnam War, twentieth century American history doesn’t make much sense). There is, indeed, considerable evidence that at least some non-acceptance of evolution is due to lack of adequate familiarity with and/or understanding of the “facts”—the evidence that evolution itself has occurred and/or what modern evolutionary theory actually claims.

At the most general level, several studies have found that level of education is positively correlated with acceptance of evolution (People for the American Way Foundation 2000; Brumfiel 2005), although this correlation seems to apply less for “Intelligent Design,” many advocates of which are highly educated (Shanks 2004; Scott 2009). More specifically, recent polls of Americans indicate low basic knowledge of science in general, and biology and geology in particular.

For example, only 38% of American adults agree that humans have more than half of their genes in common with chimpanzees; fewer than half of American adults can provide a minimal definition of the role of DNA in heredity (Miller et al. 2006; Miller 2010). Less than a third of respondents in most surveys give accurate descriptions of natural selection (Brumby 1984; Bishop and Anderson 1990; Greene 1990; Demastes et al. 1995a, b; Ferrari and Chi 1998; Anderson et al. 2002; Nehm and Reilly 2007; Gregory 2009; Nehm et al. 2009). Knowledge of the fossil record is similarly poor; only 59% of respondents to a recent poll, for example, know that the earliest humans and dinosaurs did not live at the same time (California Academy of Sciences 2009). Catley and Novick (2009) report “startlingly large” variation among college students in their knowledge of the relative and numerical timing of various events in the history of life (e.g., the age of the Earth, dinosaur extinction, the appearance of the genus Homo) (see also Cotner et al. 2010; Allmon et al. 2011 and references therein). Nelson (2008) writes that students in his college courses “thought of fossils as rare and more or less haphazardly scattered across the landscape,” rather than providing abundant and consistent evidence of the chronology of life.

Given this low level of general scientific literacy, it is not surprising that many people think that empirical evidence for evolution is sparse. For example, surveys of American college students have found that 20–50% think that there is abundant credible evidence against evolution, that modern evolutionary theory lacks “a valid scientific foundation,” and/or that “evolution is far from being proven scientifically” (Lord and Marino 1993; Cunningham and Wescott 2009; People for the American Way Foundation 2000) (as Shtulman 2006 notes, “those who do not endorse the claim that Darwin’s theory of evolution has been well supported by evidence tend to endorse the alternative claim [i.e., that Darwin’s theory of evolution has not been well supported by evidence] rather than plead ignorance”). Thus, when creationists claim that there are “no intermediate fossils” (Denton 1986; Johnson 1991; Gish 1995), when in fact they are abundant in the geological record (Padian et al. 1999; Prothero 2007), a largely uninformed public accepts such statements. As Hofmann and Weber (2003) point out, if you don’t know much about the fossil record or genetics, then critiques of evolution such as Wells (2002) can sound quite plausible. Similarly, Asghar et al. (2007) report that lack of specific content knowledge among teachers has a negative effect on the decision of whether to include evolution in their curriculum.

Students and the general public also hold a wide variety of specific misconceptions about what modern evolutionary biology says (Brumby 1984; Bishop and Anderson 1990; Ferrari and Chi 1998; Antolin and Herbers 2001; Woods and Scharmann 2001; Alters and Nelson 2002; Anderson et al. 2002; Isaak 2006; McVaugh et al. 2011; Shtulman et al. 2008; Wiles et al. 2011). For example, many think that new functional traits appear in organisms when they are needed; that evolution consists of the transformation of an entire species’ underlying essence; that it necessarily implies “randomness,” “progress,” or increasing complexity; or that it is mathematically improbable or violates the second law of thermodynamics. Such misunderstandings affect acceptance of evolution because if many people think that they understand evolution, when in fact they do not, they may not only “fail to appreciate how empirical evidence bears on evolutionary claims” (Lombrozo et al. 2006) but they can also be misled by critiques of these mistaken views (Cunningham and Wescott 2009; Jakobi 2010; McVaugh et al. 2011). That such misconceptions are at least occasionally important barriers to accepting evolution is indicated by studies in which acceptance is increased by “presenting students with a direct comparison of various naïve misconceptions associated with creationism to explanations which are more consistent with scientific evidence” (Alters 2005; see also Alters and Nelson 2002; Ingram and Nelson 2006; Nelson 2007; Verhey 2005; Wilson 2005; Wiles et al. 2011).

Another important area of “insufficient knowledge” of evolution is that non-acceptors may not understand just how useful evolution is as a scientific hypothesis. One reason scientists accept a theory is because it explains many, often diverse, observations. They may even accept ideas that might otherwise seem counterintuitive or not directly observable if they explain enough observations (e.g., relativity, plate tectonics). Non-acceptors may not be aware of how powerful evolution is as a theory, not only in how it famously “makes sense” of all of biology (Dobzhansky 1973) but also explains observations in disparate areas of applied biology of great relevance to human welfare, from domestication to medicine (Wilson 2005, 2007; Mindel 2006; Antolin 2009; O’Brien et al. 2009; Hendry et al. 2011).

Inadequate/Incorrect Understanding of the Nature of Science

Scientists and educators alike frequently state that one of the biggest causes of non-acceptance of evolution is a widespread lack of understanding of the “nature of science” (NOS; Nickels et al. 1996; McComas et al. 1998; National Academy of Sciences 1998; Nelson et al. 1998; Rudolph and Stewart 1998; Rutledge and Warden 2000; Alters and Alters 2001; Pigliucci 2002; Farber 2003; Trani 2004; Scharmann et al. 2005; Lombrozo et al. 2006, 2008; Pigliucci 2007; Scott 2009; Thagard and Findlay 2009; Ellis 2010; Kampourakis and McComas 2010; Cho et al. 2011). Scott (2009) notes that in the landmark 2005 court case on teaching intelligent design in public school classrooms (Kitzmiller v. Dover), “All of the plaintiffs’ expert witnesses spoke to the question of the nature of science…” [lack of understanding of NOS cannot be the only explanation for non-acceptance of evolution, since it does not explain “why antipathy towards the theory of evolution is stronger than to other scientific theories, such as the theory of gravity” (Evans 2008)].

Enhancing learners’ understanding of NOS is a long-standing goal of science education in general (e.g., Moore 1993; National Academy of Sciences 1998; Cobern 2000; Lederman 2004; McDonald 2010; Yacoubian and BouJaoude 2010). Part of the problem, however, is that scientists and philosophers of science themselves disagree about what exactly the nature of science is (Alters 1997; Abd-El-Khalick et al. 1998; Rudolph 2000; Lederman 2004; Abd-El-Khalick 2005; Cho et al. 2011; Duschl et al. 2011). Traditionally, “the scientific method” has been presented (especially in classrooms) as a “fairly rigid sequence of steps, followed like a recipe and leading to irrefutable results” (McComas et al. 1998). This long-standing hegemony of realism in science has, however, coexisted uneasily, almost since science began, with another very different line of thought, which emphasizes the similarities between science and other human pursuits, such as subjectivity, bias, and social influence, and argues that despite the evident success of science, we are not nearly as certain of its conclusions as we like to think. These views have gone under many names, including relativism, skepticism, deconstructionism, constructivism, and postmodernism (Golinski 1998). Thus, there is a central paradox to science: Humans appear to have the ability to sense and comprehend at least some “real” aspects of the world around us, yet this ability is not perfect, and what we make of the world is, therefore, often shaped as much or more by our feelings, hopes, prejudices, fears, desires, and preconceived ideas as it is by empirical observations and rigorous logic (e.g., Bridgman 1955; Golinski 1998; Chalmers 1999; Gauch 2003; Haack 2007; Lombrozo et al. 2008). In this view, real science as scientists do it includes an array of social interactions and “dialectical processes that shape the role theory, evidence, explanation, and models have in the development of scientific knowledge” (Duschl et al. 2011). As nicely put by Brown and Gibson (1983), “most practicing scientists know that a scientific inquiry is much more like working on a puzzle or being lost in the woods than baking cookies or following a roadmap.”

Much of the relativist/realist debates of the past couple of decades, sometimes referred to as the “science wars” (Parsons 2003), have died down, and some relatively clear standards for teaching NOS have been put forward during this time (e.g., Lederman 1992; Nickels et al. 1996; McComas et al. 1998; National Academy of Sciences 1998). Yet the relative roles of objectivity, certainty, social embeddedness, gender bias, and other factors in the process of science, and the best way to teach its apparently inescapably paradoxical character, remain complex, controversial, and unresolved (e.g., Weinberg 2001; McComas 2002; Blystone and Blodgett 2006; Haack 2007; Lombrozo et al. 2008; Yacoubian and BouJaoude 2010). This lack of consensus about what NOS actually is and especially about how it should be taught has important implications for acceptance of evolution. For instance, individuals who think that science is about absolute certainty may not understand when scientific conclusions change in light of new data or revised ideas (Chinn and Malhotra 2002). Individuals who learn that all science is a social construct may reject scientists as just another vocal special interest (Sokal 2008).

Another common example of misunderstanding of NOS in evolution education is the importance of what is usually called simply “inference” [but, more accurately, “inductive inference” (Ziman 2000)], that is, the extrapolation from observations to a larger pattern that is not observed directly. One of Darwin’s greatest innovations was to argue (following the approach advocated by his friend Charles Lyell) that one could use observed small-scale change in organisms to infer (and explain) large-scale change. The first chapter of the Origin of Species, for example, is mainly about pigeons because Darwin wanted to convince his readers of the validity of extrapolating from small changes produced by artificial breeding over short time intervals to larger changes produced by natural selection over geological time [this is sometimes discussed as an example of Darwin’s use of metaphor, which is also a means of extending reasoning from one idea to another (Young 1985; Ruse 2005; Pramling 2008; Gregory 2009b; Largent 2009)]. Change under domestication and similar phenomena familiar to most people today, such as antibiotic and pesticide resistance, or changes in the HIV virus (Freeman and Herron 2007; Gregory 2009b) are frequently acknowledged (as they must be) by creationists, who otherwise reject the validity of extrapolating from such “microevolution” to “macroevolution” (Johnson 1991). On one hand, such rejection is consistent with intuition. Surveys of both students and the general public similarly show greater acceptance of microevolutionary than of macroevolutionary concepts (Poling and Evans 2004) because the former is “directly observable” whereas the latter is not [interestingly, increasing the teaching of macroevolution seems to result, at least occasionally, in increased acceptance of evolution (Nadelson and Southerland 2010; Padian 2010; see discussion in Smith 2010b), perhaps because it involves explicating more specific examples from the fossil record]. On the other hand, rejecting the extrapolation from micro- to macroevolution is inconsistent with the application of inference common to all science. For example, if we drop a ball, we can measure how fast it falls; we can then use this result to apply to other falling objects. All scientific hypotheses are essentially about applying what is known (from observation and/or experiment) to what is unknown. If we had to personally observe everything in science to be certain of it, no progress could ever be made in our understanding of the world.

A similarly major issue around NOS and creationism is the application of materialism. Advocates of ID, for example, claim that they are challenging the “philosophy of scientific materialism, not science itself” (Discovery 2003). This is a useful rhetorical approach in their public statements as it allows them to appear moderate and reasonable and unthreatening to fields such as medicine, engineering, and agriculture that have obvious personal and economic benefits. Such critics of evolution therefore apparently allow extrapolation (of material causes) to areas that they accept, but not to areas that they do not (where they claim that supernatural causes are required). They may claim that they use science and the technology that comes from it, just like everyone else: “The possibility that divine intervention may occur…emphatically does not imply that all events are the product of an unpredictable divine whimsy” (Johnson 1995). Yet, as Pennock (1999) notes, they never explain what the methods are for determining when divine intervention is and is not to be considered potentially responsible for a particular event. While acknowledging that some theologies may describe God as capriciously and frequently intervening in the natural workings of the world, some creationists argue that a correct Christian view “holds that secondary causality (causation by natural laws) is God’s usual mode and primary causality (direct divine acts or miracles) is infrequent, comparatively speaking” and that science should not defer to such primary causality “willy-nilly” (Moreland 1989, quoted in Alters and Alters 2001). But, again, there is no definition of “willy-nilly.” This inconsistency—which Nanda (2003) has called “reactionary modernism”—cuts to the heart of the scientific method, which must consider only material causes for material phenomena. Numerous defenders of evolution have tried to approach this issue by arguing for the importance of distinguishing “methodological” materialism from “philosophical” or “ontological” materialism (Pennock 1999; Scott 2009).

Religion

Historically, religious objections were perhaps the strongest among the immediate negative reactions to the publication of the Origin (Hull 1973; Farley 1974; Ruse 1999; but see Livingstone 1984), and religious belief is widely regarded by education researchers as a major reason for modern non-acceptance of evolution (Bishop and Anderson 1990; Osif 1997; Lawson and Worsnop 1992; Sinclair and Pendarvis 1997; Aguillard 1999; Downie and Barron 2000; Antolin and Herbers 2001; Evans 2001; Brem et al. 2003; Sinatra et al. 2003; Trani 2004; Mazur 2005; Miller et al. 2006; Nehm et al. 2009; Woods and Scharmann 2001; Jakobi 2010; Paz-y-Miño and Espinosa 2010; Tracy et al. 2011). Specifically, evolution appears to call into question the literal truth of some religious scripture, not only in the Judeo-Christian Bible (Cantor and Swetlitz 2006; Robbins and Cohen 2008) but also the Quran (Edis 2007) and Hindu texts such as the Bhagavad Gita (Brown 2010). More generally, however, evolution is seen by many critics as “more than a scientific theory—it is a powerful medium for the propagation of materialism and atheism…associated with a variety of social ills: racism, moral relativism, abortion, pornography, and the breakdown of the family unit…”; for many, “acceptance of evolution necessarily entails commitment to materialistic atheism…”; evolution, in this view, is “not just science, but an anti-religious ideology” (Harrison 2010).

Non-acceptors of evolution frequently express the view that acceptance of evolution would entail the acceptance of a host of ideas that they find unacceptable: that life has no purpose or meaning; that races or ethnic groups are inherently different; that there can be no supreme being, afterlife, or spiritual rewards; that evolution means that people are “nothing more than animals” and therefore hard-wired for selfishness and ruthless behavior; and that there can be effectively no free will or self-determination. Research has specifically found that creationists who are exposed to evolutionary theory, including its implication of a close connection between humans and other animals, have increased thoughts of mortality (Tracy et al. 2011). Individuals frequently respond to such existential threats by “becoming more accepting of a theory that offers a greater sense of meaning by depicting human life has having ultimate purpose…” (Tracy et al. 2011). For all of these reasons, the purposeless, materialistic aspect of Darwinian evolution is highly repugnant to many people (Gould 1974). Intelligent design proponent Phillip Johnson’s fundamental objection to evolution, for example, is precisely what he sees as the pernicious effects of materialism (Johnson 1995; see Pennock 1996, 1999). Similar feelings are likely widespread. As Thagard and Findlay (2009) put it: “People do not just think that evolution by natural selection is false; they want it to be false. Even people who believe in evolution may admit that they want it to be false!”

Many evolutionists have argued that evolution necessitates none of these conclusions (Miller 1999; Scott 2009; Mead and Scott 2010a, b; see Allmon 2009 for a review), and—as widely emphasized by evolution advocates—most “mainstream” Christian denominations have accommodated evolution [Martin 2010; even though such accommodation has its critics on both the religious and anti-religious sides (Allmon 2009)]. Several authors have suggested that if students knew that such accommodation is possible, it might lessen their resistance to evolution (Colburn and Henriques 2006; Scott 2009). Yet such messages are apparently not widely heard by the general public, perhaps in part because of contrary views loudly voiced by other evolutionists that religion and evolution are wholly incompatible (e.g., Dawkins 2006; Dennett 2006; Provine 2006; Coyne 2009b). Indeed, at least a few studies of undergraduates have found that increased exposure to evolution produced decreased acceptance and/or increasingly negative perceptions regarding the consequences of accepting it (Brem et al. 2003; Sinatra et al. 2003; Lovely and Kondrick 2008). For example, in his course on evolution for non-majors at Cornell University which he has taught for more than 20 years, William Provine has found that between the beginning and end of the course, not only does the percentage of students accepting evolution go up but so does the percentage firmly rejecting it (W. Provine, personal communication).

Psychological Obstacles

A large and rapidly growing body of psychological research points strongly to a major role for psychological factors in how and why particular ideas are more readily adopted than others, and such factors constitute a significant but frequently underrecognized element of non-acceptance of evolution. They can be grouped into at least two categories. First are the numerous processes by which the human mind appears to overrule what the senses are telling it and which lead to decisions that appear counter to the perceived empirical state of the physical world. Second are specific, apparently innate psychological characteristics and biases in how humans interpret the world.

As much as logic and rationality contribute to human thought and despite the rise in the influence of science in modern society, human reasoning is still suffused with “affective” influences—emotion, wishes, hopes, beliefs, faith, illusions—that fly in the face of the “facts” (e.g., Harvey 1992; Sutherland 1994; Pohl 2004; Gordon et al. 2005; Fine 2006; Kida 2006; Bering et al. 2011; Mooney 2011; Shermer 2011; Watts 2011). One of the explanations for such psychological devices appears to be to minimize cognitive dissonance—the psychological discomfort caused by mutually contradictory cognitions—which leads a person to avoid or ignore additional information likely to increase the dissonance and to seek out additional information that will reduce the dissonance (Harmon-Jones et al. 1999). Cognitive dissonance has been suggested as an explanation for or contributor to a host of human behaviors that go against what a purely rational or logical assessment of available empirical information would suggest, including optimism, wishful thinking, gambling, entrepreneurship, and many other things that people do every day (Griffiths 1990; Liang and Dunn 2008; Krizan and Windschitl 2009 and references therein). Such behaviors, of course, sometimes are highly beneficial. Optimism, for example, is frequently associated with better physical health, more persistence in educational efforts and personal relationships, and resilience to stressful life events and may be, at least to some degree, “hard-wired” into the brain (Armor and Taylor 2002; Carver et al. 2010; Barefoot et al. 2011; Sharot 2011). Yet there is also evidence that optimist tendencies can lead to engaging in risky behaviors, which can be hazardous to health and well-being (e.g., Lovallo and Kahneman 2003; Isaacowitz 2005; Jansen et al. 2011; Sharot 2011).

More significant intentional or unintentional psychological dissociation, labeled by psychologists as “self-delusion” or “self-deception,” allows people to persuade themselves to believe (or accept) what they rationally “know” is not so (Fingarette 1969; Audi 1988). Psychologists disagree, however, on exactly what causes or allows this phenomenon (Trivers 1985; Scott-Kakures 1996; Lazar 1999 and references therein). One interpretation is that although the self-deceiver holds two incompatible beliefs and at the same time, one of the beliefs is somehow not consciously “noticed,” thus allowing the two to avoid direct comparison and so the realization of their incompatibility. In this sense, most people hold numerous self-contradictory beliefs, “if only because we cannot see far enough into the implications of each of our beliefs” (Fingarette 1969). As Shermer (2007) puts it: “Smart people believe weird things because they are skilled at defending beliefs they arrived at for non-smart reasons.”

Although I am not aware of any psychological research that specifically addresses the issue of cognitive dissonance and evolution, it seems reasonable to suggest that it is, at least in part, in an effort to avoid cognitive dissonance that individuals committed (for whatever reason) to not-accepting evolution will—by one or more mechanisms like those described above—resist embracing, or even encountering, evidence or arguments that evolution is true.

How we think may also affect what we accept. Woods and Scharmann (2001) found a significant correlation between logical thinking skills and acceptance of evolution. Sinatra et al (2003) similarly reported that students with more sophisticated and flexible styles of knowledge and learning were more likely to accept evolution. In several papers, Lawson and colleagues found that “reasoning ability” was a strong predictor of the number of misconceptions held by seventh grade students about genetics and natural selection, and that “less skilled reasoners” were more likely to have nonscientific beliefs initially and less likely to change those beliefs after instruction (Lawson 1985; Lawson and Thompson 1988; Lawson and Weser 1990).

Numerous studies have suggested that evolution runs counter to particular aspects of human psychology. Several authors, for example, have noted that evolution is in some ways counterintuitive (Mayr 1982; Evans 2008; Williams 2009; Wiles 2010); for example, evolutionary thinking states that the apparently stable present world of everyday experience is a result of ceaseless change and that complex structures arise from less complex without a conscious designer. Some of these “everyday” modes of thinking may be innate patterns and modes of understanding, which coincidentally frequently tend to resonate better with creationist views (Evans 2000b, 2008; Poling and Evans 2004). These patterns or biases appear very early in human development and may constrain “human cognition such that creationist ideas are attractive and easier to spread, whereas evolutionary ideas are less contagious” (Evans 2008). Non-belief in evolution, therefore, may well begin “with the natural, intuitive development of ‘creationist’ ideas as a very young child” (Williams 2009). Among such potential cognitive biases, “two staples of Western philosophical thinking” in particular “serve to inhibit the expression of natural explanations for the origins of species” and evolutionary change (Evans 2001): essentialism and teleology.

Political/Social Influences

Political and social influences may at first seem like what are herein referred to as “ultimate/secondary” causes for non-acceptance of evolution (Table 2) because they provide the milieu in which other factors act, rather than acting directly to cause particular behaviors or mental conceptions. Yet this is probably an oversimplification because social and political factors can, at least occasionally, act directly on individuals and affect their conceptions about the world.

For example, rejection or acceptance of an idea may depend not only on its empirical, philosophical, or psychological characteristics but also on who suggests, supports, or attacks it. It may be difficult, for example, to reject a view provided by parents or another authority figure because this may, in the mind of the recipient, be equivalent to rejection of that individual or institution (Demastes et al. 1995a; Woods and Scharmann 2001; Williams 2009; Wiles et al. 2011). This can readily translate into politics. The process of deciding who is a legitimate authority on particular topics (such as science) can be socially or politically determined; an individual’s political affiliation and views about morality and social order, for example, strongly predict whom they consider to be a legitimate scientific expert (Kahan et al. 2011; Mooney 2011). Thus, some people may not accept evolution because it is associated in their minds with a sociopolitical agenda that they find otherwise unacceptable.

In the U.S., evolution is highly politicized compared to other developed countries (Forrest and Gross 2004; Gibson 2004; Shanks 2004; Miller et al. 2006; Berkman and Plutzer 2010) and, as Woods and Scharmann (2001) put it, “acceptance of evolutionary theory will continue to engender frustration in the United States as long as the cultural and/or political milieu dictates that it must be so.” Political orientation is nearly as powerful as education in predicting evolutionary belief in Americans; the alignment of individuals, groups, and political parties concerning evolution closely resembles those found with same-sex marriage, abortion, and other controversial “social” issues (Berkman and Plutzer 2009). Self-identified political liberals are more likely than political conservatives to accept that humans evolved from earlier species (Mazur 2005), and the more conservative a person’s political views, the less likely he or she is to accept a great age of the Earth (Cotner et al. 2010). In the 1990s, the Republican platforms in seven states included explicit demands for the teaching of “creation science” (Paterson and Rossow 1999; Miller et al. 2006). Such political effects on evolution acceptance are not limited to the U.S. Although Hindu creationism may be motivated by belief that scriptures such as the Bhagavad Gita are definitely authoritative, it also has significant roots in Indian reaction to British colonial rule (Brown 2010).