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From the Introduction

One may have good reasons to worry that the public, broadly construed, holds unscientific views about several aspects of human life. For instance, 42 percent of Americans believe that people are born homosexual, a percentage that has increased significantly since 1977, whereas more than half the people in Canada and Great Britain seem to think the same. It has also been found that approximately one in four people in the United States, Canada, and Great Britain believe that the position of the stars and planets can affect their lives. Finally, polls since 1982 until very recently show that over 40 percent of Americans accept the idea that God has somehow created humans in their present form. There is also academic research suggesting that people tend to perceive evolution as a purposeful process, as well as believe that genes determine our traits and disease. These, and other, findings support the conclusion that unscientific notions are rather widespread, although one should always be cautious about the possible interpretations of research findings about public opinion.

What is common in all these views? One common aspect is the idea of determinism. People think that genes, or something else innate, determine traits, disease, and even behaviors (such as homosexuality), whereas we know that in most cases these are the outcome of complex interaction between genes and environment; people think that the stars determine our lives, even though the stars are too far to have any empirically measurable effect on us; and people think that God determines how we are and look, even though we exhibit so many features that would make any designer feel embarrassed. Another common aspect of these views is the idea that in all of these cases there is a goal, which could be the outcome of purpose, intention, or design. When people think that genes, stars, or God determine our features and/or aspects of our lives, the underlying assumption is that there is some underlying plan toward some specified end point. However, a close look at the conclusions of research in developmental biology, human history, and evolutionary biology show that the course and outcomes of life are not predetermined based on some kind of plan, but rather that they can be influenced by particular combinations of critical events.

Let me clarify the terms I am using throughout the book. There are three closely related concepts (the first two are often considered synonyms), but they are distinct: fate, destiny, and design. Historically, fate and destiny have been defined in a variety of ways. However, fate is a concept that denotes that there are several aspects of our lives that we do not choose and do not control. We did not choose our parents or our biological characteristics, for instance. There are indeed some features that we are predisposed to have, such as having two eyes and two ears, or two legs and two arms. We do not anticipate human development to result in wings or beaks. It is only in this sense that a kind of developmental fate is conceivable. However, the impact of fate in our biology is sometimes exaggerated in the minds of people, resulting in the conception that I describe as genetic fatalism. This view is explored in chapter 2, and part 2 of the present book provides concrete examples that challenge it.

Destiny is a concept that denotes that one can foresee future outcomes by evaluating particular elements that are already present or that have been present in the past. Based on these, one can make a projection to the future and imagine future outcomes, by envisioning what one could become based on what one already is. For instance, one may predict that a child who is extremely intelligent and has a great interest for nature is destined to become a great scientist. Or that someone who has a talent in music or arts is destined to become a musician or an artist. For some people believing in astrology, even the day when one was born is informative for what will happen in the future. The difference with fate is that one’s destiny cannot be just realized without effort and decisions. However, the idea of destiny is often misconstrued by people, who do not realize the impact of events within and outside our control and who think as if destiny is a predetermined outcome that will emerge one way or the other. This view is explored in chapter 3, and part 3 provides concrete examples that challenge it.

Finally, design is the idea that the world as we see it is the intentional work of a conscious, intelligent agent (usually God, however conceived) who designed it purposefully. As a result of this design, the physical world has all the properties that are necessary for the emergence of life. A related idea is that the universe also has all of those conditions that are necessary for the emergence of sentient beings such as ourselves, so that our presence in this world was inevitable under these conditions. Some people also claim that organisms exhibit such an enormous complexity in their structures and functions so that the most plausible explanation is that they were specially created and intelligently designed by God. This central idea here is that the complexity of organisms is so enormous that their emergence through natural processes is simply inconceivable; therefore, according to this view, organisms can only have been designed by an intentional and intelligent agent. This view is explored in chapter 4, and part 4 provides concrete examples that challenge it.

In the present book I argue that genetic fatalism, destiny, and intelligent design are insufficient and illegitimate accounts for human development, human life, and human evolution. In all cases, outcomes are better accounted for by considering robust processes (developmental, historical, and evolutionary), as well as critical events that affected which one of several possible directions these processes took. To support this argument, I draw on published research that should nevertheless be considered as a representative and indicative sample of huge bodies of research, rather than an exhaustive account. I focus on studies reporting academic research, and in all cases I am citing research articles that I find indicative of the respective findings and relevant to the argument I am developing in this book. This is especially important to keep in mind both about the research about the conceptions that people hold presented in the first part of the book, and about the research involving organisms, DNA molecules, fossils, and so on presented in the rest of the book.

In all cases, there are particular limitations that relate both to the object of the analysis itself and to the methods used. These limitations usually have an impact on the data obtained, and this should be taken into account in how these data are interpreted. This is especially important for the first part of the book, which presents research on human conceptions. As some researchers nicely put it, most people in the world are not WEIRD: Western, Educated, Industrialized, Rich, and Democratic. Yet this is the kind of people involved in much of the research presented in the first part of the present book (mostly from Europe and North America; the country in which a study took place is specified each time). The fact that the research that I present mostly comes from Europe and North America may be interesting to many of the readers of this book because they may also come from those parts of the world. But at the same time, these people represent a minority of the people currently inhabiting our planet, about 12 percent of the total population according to an estimation, and so one had better refrain from generalizing from this research. There are other specific problems relating, for instance, to extracting and analyzing DNA from fossils. Furthermore, researchers make any interpretations within particular theoretical frameworks that also need to be taken into account when one is considering their conclusions. All of these together produce evidence that supports, or not, particular hypotheses. Evidence becomes stronger only when there exist many studies in a field and researchers conduct robust meta-analyses in order to acquire a view of where the field as a whole is going. Therefore, evidence is not something independent and absolutely objective, but depends on one’s interpretation; it is, generally speaking, anything that can make a difference to what one is justified in believing.

This being said, I should note that my main aim in this book is exactly to argue what the available empirical evidence makes us justified in believing about life. As I have already mentioned, robust developmental, historical, and evolutionary processes produce life outcomes. However, the details of these outcomes depend on particular critical events and are in no way predetermined. As I show in parts 2, 3, and 4, the outcomes of human development, human life, and human evolution are what they are because of particular critical events with particular outcomes in the context of broader natural processes; they are not the predetermined outcomes of fate, destiny, or design. This entails that the related beliefs that I present in part 1 are largely unjustified. Therefore, my aim in this book is to make readers appreciate the impact of critical events in life, against any notion of design, goal, or purpose.

In particular, I draw on developmental biology, history of biology, and evolutionary biology to show that human development, human life, and human evolution have a common underlying principle: outcomes are not predetermined but are shaped by critical events. Human development, life, and evolution are historical processes: they are sequences of successive events that are unique in space and time; that is, they took place at a certain time in a certain place—not anywhere, anytime (the philosophical term for this is that they are “spatiotemporally” unique). Thus, critical events can influence the course of the respective processes and make a difference in which one of several possible outcomes will materialize; which one this will be is previously unpredictable, but once it occurs there is a causal dependence of the future on that. We tend to think in terms of design and intentions because we usually consider only the actual outcomes but not the unrealized or currently nonexistent ones. This entails that we try to explain the outcomes in hindsight based on what we know that happened, and therefore the actual outcomes seem to us to be natural, predetermined, and even inevitable. However, the outcomes of human development, life, and evolution are neither predetermined nor entirely random; they are historically contingent.

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To sum up: critical events shape outcomes by influencing the direction of a process toward a particular path among several possible paths. Which of these will be followed is previously unpredictable, but once taken the outcome depends on it. In Turning Points, I argue that this causal dependence often makes us in hindsight perceive outcomes in our development, lives, and evolution as inevitable. This we do because in hindsight we selectively pick up past events and use them to explain these outcomes as inevitable, overlooking the impact of critical events that were turning points. Yet, I argue, many of these outcomes were evitable, because they were causally dependent upon unpredictable critical events. Our development, life, and evolution could have thus taken other paths, resulting in different, alternative outcomes than those that actually occurred.