The preceding discussion should have made clear that the notion of final cause or purpose as an explanatory element is lacking in many respects. It does not offer any convincing and scientifically useful explanation for most phenomena of nature. One exception, perhaps the only one, is some aspects of human behavior as mentioned above. Despite the logical deficiencies inherent in teleological explanations, they persist in many areas of biology and in some areas of psychology. On the contrary, in physics and chemistry, explanations in terms of purpose or final cause were already beginning to be abandoned in classical Greece. Even the champion of teleological thought, Aristotle, realized that many phenomena in physics required other kinds of explanations. By the 17th century, teleology had essentially disappeared from physics. In Newton's mechanics, there is no teleology left. For example, the movement of bodies can be explained in terms of cause instead of in terms of purpose. The impact of a moving body A on another moving body B can be entirely explained considering their masses, speeds, directions of movement, elasticities and so on. The importance of each of these factors can be precisely expressed in an equation and accurate predictions can be made. Instead of explanations in terms of function or purpose, Newtonian mechanics offers explanations in terms of causes and ensuing effects. Modern science is essentially based on this kind of explanation and it is quite likely that the change from an emphasis on function to an emphasis on causes has been a major factor in scientific progress. Questions like 'why?' and 'what for?' have been replaced by questions of 'how?'. The 'how?' question can be answered by causal explanations, but it can also be taken a step further in the way that we can explain 'how' without considering a cause. As an example, we could use Einstein's law of gravitation. It simply states that the path and speed of a planet are so adjusted that the total separation, measured over any section of its course, shall be a maximum. This law explains how a planet moves, but it does not say a word of why the planet follows a course of maximum separation or the cause of its movement (Hull, 1959). It offers a pure description of a phenomenon, but that description is enough to allow us to predict the planet's path, even in a distant future. The accuracy of the predictions can in no way be improved by references to metaphysical questions of 'why?' and 'what for'?
The spectacular progress that followed the disappearance of teleology from physics and chemistry is now repeated in molecular biology, a branch of biology where teleology has become efficiently eradicated. This is also the case in the neurosciences. Most of contemporary neuroscience offers strictly mechanical, causal explanations of the mysteries of nerve cell function (Revonsuo, 2001). One immediate consequence is that nervous functions have become less mystical than ever. The intimacies of the sodium channel or of transmitter release can be entirely explained in causal, mechanistic terms without any reference to purpose. According to Revonsuo (2001), within the neurosciences there is only the subfield of cognitive neuroscience that still persists in the employment of non-mechanistic, non-causal explanations. The consequence is that no single cognitive component has been discovered for which there is general agreement among investigators (Van Orden and Paap, 1997). It is my firm belief that behavioral sciences could also benefit from abandoning teleological explanations and concentrate on causes rather than on purposes. The potential fruitfulness of such an approach will, hopefully, become apparent during the reading of the remaining parts of this chapter.
Before returning to the subject matter of this book, it can be useful to make a short comment on what is meant by explanation in terms of cause-effect. It appears that one of the first comprehensive analyses of this was presented by David Hume in his An Enquiry Concerning Human Understanding (Hume, 1758). Briefly, there are three components of all causal relations: contiguity of time and place, temporal priority of the cause, and constant conjunction. If we imagine that C causes E, then C and E must occur at the same place and about the same time (contiguity of time and place), but C must always precede E (temporal priority). Furthermore, if C is present, then E must invariably occur. There is nothing inherent in C that determines E, so a relation cause-effect can only be discovered by experience. Hume himself mentions that there is no logical reason for a moving billiard ball to make a second ball start moving upon contact with the first. However, since this always occurs we can conclude that the first ball causes the second to move. An interesting consequence of this argument is that reason is not the basis for discovering any cause-effect relationship. It is only experience that can allow us to discover such relations. If we want to apply this to our search for understanding sexual behavior, it must be concluded that we should not think of the behavior but observe it. Experiment, not reason, will illuminate us.
There is one additional issue that needs to be addressed before we can leave the discussion of cause. In teleology, as well as in biology, it has been customary to divide causes into two kinds, efficient cause versus final cause in classical teleology, and ultimate versus proximate cause in biology. Let us start with teleology. The efficient cause is the immediate cause of an event while the final cause is the purpose. If eggs are being fried, the final cause may be my breakfast, but the efficient cause is the heat applied to the frying pan. In this example, the coagulation of the proteins in my egg is caused by heat and nothing else. The conformational changes in the proteins underlying coagulation can be entirely attributed to increasing temperature. The efficient cause explains completely the phenomenon of an egg being fried, that is the 'how?' question. The answer to the 'why?' question, I will have fried eggs for breakfast, does not contribute in the slightest to an understanding of what is happening in the eggs. Furthermore, I may apply heat to eggs for many reasons in addition to having them for breakfast, meaning that the final cause of the event 'eggs being fried' can be variable and it cannot be inferred from the event itself. The ambiguity or even arbitrariness inherent in the process of assigning a final cause to an event becomes particularly evident in the behavioral sciences, where it normally is an observer and not the behaving individual who will have opinions about the purpose of the observed behavior. Let us for a moment return to my walk to the city center. I know that the purpose, or final cause, is to have beer with friends. However, another friend who saw me walking in the direction of the city center may well imagine that I did that because I was on my way to a movie theater. She came to that conclusion because she had heard that an excellent movie was playing that week. A colleague who also saw me might have concluded that I was going to the long distance bus terminal to pick up a visitor. He had done that himself a couple of days ago. As soon as an observer imputes a purpose to another individual's behavior, he is likely to do that according to his personal inclination. This is far more evident when we try to give a purpose to the behavior of individuals belonging to a species different from our own. It is quite sufficient to hear someone describing the extremely purposeful behavior of his dog to discover the absurdity of the reasoning behind. It seems, then, that explanations of behavior in terms of purpose, i.e. teleological explanations, are extremely risky, perhaps with the exception of accounts of our own behavior. Personally, though, I find that my own behavior normally defies any rational explanation.
In biology, the term 'efficient cause' has been replaced by 'proximate cause', and 'final cause' with 'ultimate cause'. The adjective final comes from the Latin word finalis, meaning of or pertaining to an end, while the adjective ultimate is derived from the Latin word ultimus, meaning last, final. It seems that final and ultimate causes are not only conceptually but also semantically equivalent. The reason why biologists have replaced final with ultimate is perhaps to make the expression's teleological foundations less evident and the association with metaphysics less salient. Having said this, it should also be emphasized that many biologists are quite comfortable with teleological explanations. It is particularly, or perhaps even only, in evolutionary biology that these kinds of explanations are legion. The prime example, however, comes from the popular quasiscientific discipline of evolutionary psychology, where teleology is not only accepted but also venerated (see e.g. Wakefield, 2005). Some of the excesses of evolutionary psychology will be illustrated in a few pages. The more sen-sate biologists will, nevertheless, maintain that the complete explanation of a phenomenon includes an answer to the question 'why?'. This 'why?' does not necessarily mean 'what for?', a reference to the purpose. It can also mean 'how come?', which is a reference to the evolutionary processes that underlie the phenomenon (Mayr, 1961).
In this latter question, there is no reference to purpose and an answer to it would not belong to teleology. Although the distinction between the questions 'what for?' and 'how come?' could easily be maintained, many biologists fail to do that and explanations in evolutionary biology are frequently offered in teleological terms (see Mayr, 1997). When it comes to behavior, it can be maintained that the evolutionary processes responsible for it, if any, are of no immediate interest. If we understand how the behavior is controlled by internal and external causes we have achieved a complete explanation. The evolutionary history of these causes is entirely irrelevant. It is likely that this principle could apply to most organismic phenomena, in addition to behavior.
Let us take a simple example. For the sake of clarity, I use the behavior of an inanimate entity. My car is equipped with ABS brakes. I happen to know the history and purpose of this kind of brake. One morning I discovered a serious malfunction in them. So serious that I almost ended in the ditch. That event made it evident that they needed repair. Here, my knowledge of the history of the ABS brakes was of no more use than my knowledge of their purpose. The mechanic who fixed them, a young woman, had never heard of their history and she had very vague ideas about their purpose. However, she knew how they worked. Such a simple example should be enough to illustrate that knowledge of evolutionary history or purpose is of little practical value. It may satisfy or thrill our intellect and constitutes, perhaps, a healthy entertainment. Nothing more.
To summarize, it can be maintained that metaphysical explanations, including teleological, have no place in science. Consequently, explaining behavior in terms of its function should be abandoned. On the contrary, any meaningful analysis of behavior requires the establishment of cause-effect relationships. The only way to do so is by careful observation and, whenever possible, with the aid of rigorously designed experiments.
Within the behavioral sciences, the principles outlined in the preceding paragraphs have been dominant in the behaviorist, neobehaviorist and radical behav-iorist traditions. The splendid learning theories of Hull (1943) and Spence (1956) are good examples of how behavior has been carefully analyzed in terms of cause-effect. Skinner has taken that tradition a step further in his insistence of act - consequence (cause-effect) as the basic principle determining most of human and non-human behavior. I maintain that sexual behavior in mice and men also can be analyzed and understood in terms of cause-effect relationship. I also insist on Hume's criteria of contiguity and conjunction. Since reproduction (birth of the young) is non-contiguous with sex behavior, it can have no causal relationship to it. This argument lacks force, though, if with reproduction we understand fertilization. Although not simultaneous, fertilization is always temporally associated with sex behavior. What is far more important is that there is no constant conjunction insofar as sex is not always associated with reproduction. In the human, the vast majority of sexual activity has no reproductive consequences and in other animals the association is uncertain. Data from an old Swedish survey of sex behaviors show that there are about 1100 copulations per birth, making an association between sexual intercourse and reproduction something quite exceptional. Likewise, female mice, rats and rabbits copulate with a large number of males during the period of estrus, yet only one of the males will sire offspring. The display of copulatory behaviors by all the other males had no reproductive consequence.
The preceding examples illustrate that there is no constant conjunction between sexual behavior and reproduction. Thus, according to the criteria of causality established by one of the most respected philosophers of all times, David Hume, sexual activity is not causally related to reproduction. I hope that the claim I presented several pages ago, that sex behavior is independent of reproduction, thereby have been substantiated. A caveat needs to be presented immediately in order to avoid exaggeration. Reproduction is not possible without sex behavior and, whenever reproduction occurs in animals with sexual reproduction, sex behavior has been executed at one moment or another. This means that the relation sex behavior - reproduction is asymmetrical. It is very well possible to have sex without reproduction, but reproduction is not possible without preceding sex behavior. This asymmetry is unprob-lematic and the easiest way to handle it is by considering reproduction as an occasional, physiological side effect of sex behavior, without any importance for the mechanisms determining that behavior.
The asymmetric relation between sex behavior and reproduction can probably explain why some biologists have insisted on a necessary association between the two. This can easily be illustrated by an example where reproduction (or better fertilization) is the event R and sex behavior is the event S. We can formulate the law that if R, then it was preceded by S. The principle of constant conjunction is therewith satisfied. The principles of temporal priority and contiguity are also satisfied, since sex behavior preceded reproduction (fertilization) and reproduction (fertilization) was contiguous with sex behavior. Thus, S is the cause of R, in other words sex behavior causes fertilization. According to a biological point of view, then, it is entirely legitimate to associate sex with reproduction. On the contrary, if the starting point is S, then we can formulate a law saying that if S, it is not always followed by R. From the behavioral point of view, as mentioned, there is no causal relationship between S and R. It appears, then, that if our focus of attention is on mechanisms of reproduction, then it is reasonable to maintain an obligatory relationship between sex behavior and reproduction, while if our focus is on behavior, then it is reasonable to reject such a relationship. Since the subject of the present discussion is behavior, I consider sex behavior as a non-reproductive behavior.
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