The Unnatural Nature of Science Read online

  I would almost contend that if something fits in with common sense it almost certainly isn’t science. The reason, again, is that the way in which the universe works is not the way in which common sense works: the two are not congruent. Our brains – and hence our behaviour – have, in evolution, been selected for dealing with the immediate world around us. We are very good at certain types of thinking, particularly that which leads to both simple and quite complex technology and control of our immediate environment. Scientific understanding, however, is not only unnatural: for most of human evolution it was also unnecessary, since, as will be seen (Chapter 2), technology was not dependent on science.

  It is precisely the unnatural nature of science that, historically, made it so rare. Unlike science, many features of human behaviour combine unconscious thinking and learning. In marked contrast to their ignorance of physics, most people can carry out the most remarkably complicated actions, such as riding a bicycle – a very difficult problem in Newtonian terms. A remarkable example of how internal mental representations can be used for complex tasks comes from the study of the ways in which Polynesians navigate between distant islands. They use a method involving ‘dead reckoning’ in which they conceive of the boat as stationary, with the islands moving past it and the stars wheeling overhead. The process has been likened to walking blindfolded between two chairs in a large hall while pointing continually to a third chair off the main path. Such a method of navigation requires no understanding of why it works: it is quite different from one based on science and technology and emphasizes the adaptiveness of human thinking to deal with innumerable problems. While learning is essential, understanding is not.

  *

  Unlike science, everyday common-sense thinking is characterized by its naturalness. It involves complex mental processes of which we are usually quite unaware but which allow us to deal with the requirements of daily life. For most of everyday life it works extremely well, but for science it is quite unsatisfactory. It is quite different from scientific thinking, lacking the necessary rigour, consistency and objectivity. Most people regard their ideas about the world as being true without being aware of the grounds for a particular belief. This is quite unlike the self-aware and self-critical methodology of science. Common-sense thinking is also prone to lead to error, particularly when formal problems are posed and when the information available is limited. Indeed, common-sense thinking is not concerned with tackling formal problems or generating general solutions. The differences between common-sense thinking, and scientific thinking can be illuminated in two ways: first by looking at the way in which children develop their thinking and then by looking at some aspects of adult thinking.

  The perceptual world of the young infant is much more structured than it was previously thought to be. Two-year-olds already understand cause and effect, asking of a broken cup, ‘Who broke it?’ They also recognize that symbols – words, for example – can stand for things apart from themselves, and they like to put things into categories by colour or size. By their fourth birthday, children appreciate that the appearance of an object – a stone egg for example – may not reveal its true identity. In very general terms, children learn by direct experience, authority, intuition and logic. All of these lead to a common-sense view of the world, but not to a scientific one.

  As the Swiss psychologist Jean Piaget has said, every child, at an early stage, fills the world with spontaneous movements and living forces. Waves raise themselves, clouds make wind, and these movements are due to internal and external actions – the objects have a free will of their own. Thus the lake attracts the rivers which wish to go there. Some of the explanations of older children even resemble the physics of Aristotle – for example, the idea that a thrown object is in part moved by the air through which it moves.

  There is thus a ‘magical’ aspect to children’s thoughts. In part this may be due to the failure of the infant to distinguish between himself or herself and the world. Whatever the explanation, children believe that mental operations can influence an event that is desired or feared. This is illustrated by the writer and critic Edmund Gosse, who was brought up in a strict Victorian environment in which all imaginative life was forbidden. He was never told stories. He had no friends, and all his reading was pious or scientific. But he wrote that by the age of five or six he had

  formed strange superstitions … I persuaded myself that, if I could only discover the proper words to say or the proper passes to make, I could induce the gorgeous birds and butterflies in my Father’s illustrated manuals to come to life and fly out of the book … During morning and evening prayers … I fancied that one of my two selves could flit up, and sit clinging to the cornice, and look down on my other self and the rest of us, if only I could find the key.

  Piaget has characterized two aspects of children’s theory of the world: animism, the tendency to regard objects as living and endowed with will, and artificialism, the idea that everything is made by someone for a special purpose. When a six-year-old is asked what the sun is made of, the reply is ‘Of fire.’ But how? ‘Because there is fire up there.’ But where did the fire come from? ‘From the sky.’ How was the fire made in the sky? ‘It was lighted with a match …’ There is a spontaneous tendency towards animism, for the child to believe as if nature were charged with purpose and as if chance did not exist. When a child says the sun follows us, the child attributes purposiveness to the sun. But when asked ‘What is a fork?’, the reply is ‘It is for eating with’ – an artificialist response.

  This is evident in relation to the birth of babies. Sometimes the baby is assumed to have existed prior to birth and the child simply asks where it was before. The child may also ask how babies are made, and birth may be conceived by the child as an artificial process of production, like modelling Plasticine, for example. On the other hand, there are often reports of beliefs that babies come from their parents’ blood or from the mother’s mouth or navel.

  One of the most important ideas which lie at the heart of common sense is the idea of cause and effect. Three-year-olds have quite a sophisticated causal understanding of mechanical interactions. The origins of understanding causality have their origins in infancy, and there is now evidence that infants as young as six months perceive causal events. Contrary to David Hume’s classical eighteenth-century account, according to which the perception of causality is assumed to be due to the repeated observation of a conjunction between two events, there is evidence that causality is perceived directly almost as a gestalt – that is, as a whole, all at once – in which experience is not important. So, when adults are shown quite abstract stimuli, such as coloured lights with particular movement patterns in relation to each other, causal relations between the lights are proposed even though the observer knows how the stimuli were produced. Thus instead of the appreciation of causality being a result of gradual experience, it seems as if the perceptual system is disposed to assume it. If this were also true for other learning processes, it could require one to abandon much that common sense teaches us.

  Children pass through several stages in their competence to perform particular tasks, but they always have satisfactory explanations for their own behaviour. For example, in Piaget’s famous conservation task a child sees two identical glass containers filled with water and judges them to contain the same amount of water. As the child watches, one container is emptied into a glass which is taller and thinner, and so the water rises to a higher level. Before children have acquired the concept of conservation of quantity, they will conclude that the amount of water has now increased. Both children who do not understand conservation and those who do will provide what is, from their point of view, a logical explanation for their answer. For example, ‘non-conservers’ will point out that the water has risen to a higher level in the taller, thinner glass, so clearly there is more water in there. For them their answer is correct and obvious. It is, perhaps, not unlike it being ‘obvious’ to any reasonable person that th
e sun moves round the earth.

  Older children have quite well-developed ideas about the nature of the world before they are taught science in school. Many of these ideas might be characterized as being naïve or natural thinking, and they are again best illustrated with respect to physics. For example, children suggest that the higher up an object is lifted, the more it weighs, since when it falls to the ground the impact is greater. ‘Hot’ and ‘cold’ are considered to be different but related properties: hence some of the cold is thought to leave an ice cube and go into the surrounding water, rather than heat being required to melt the ice and so cool the water. And, to give a biological example, it is widely thought that plants get their food from the soil, rather than from sunlight. (They do, of course, get nitrogen from the soil, but this is not food, for it provides no energy for the life of the plant.) All are common-sense theories, but wrong.

  An important feature that has emerged from studies of students’ thinking is that inconsistencies in their explanations are usually not noticed, and, if they are noticed, they are not regarded as an important issue. Much of the causal reasoning of students is based on a preference to see change in terms of a simple linear causal sequence or chain of events. This may be the root of the difficulty they have with concepts involving reversibility. They understand how an input of energy can change the state of a substance from a solid to a liquid but not the reverse process, when the liquid solidifies. Studies have shown that a number of key reasoning processes need to be learned before children can grasp the basic nature of the physical world. These include the idea of variables in thinking about causal events, together with the necessity of changing the variables one at a time if a proper comparison of their effects is to be made (in thinking about a simple case of equilibrium, such as in balancing a beam, for example, there are four variables – two weights and two distances from the point of support); the idea of probability and correlation; and the whole idea of abstract models to explain, for example, the solar system or the weather. None of these ideas is really natural, and when children have learned these ideas their success in science tests improves dramatically.

  Such studies confirm that scientific thinking differs from everyday thinking not only in the concepts used but in what constitutes a satisfactory explanation: common-sense thinking about motion, for example, is not concerned with the spelling-out in detail of the relationships between terms such as force and velocity – each involving strictly defined and quite difficult concepts – but can be satisfied with vague statements. A further difference is the purpose behind scientific thinking and the thinking of everyday life. In everyday life one is primarily concerned with usefulness, whereas science is concerned with a rather abstract understanding. This is exemplified by Sherlock Holmes when he turns to Watson, who has been castigating him for not knowing about Copernicus and the solar system, and says, ‘What the deuce is it to me if you say we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or my work.’

  In fact one of the strongest arguments for the distance between common sense and science is that the whole of science is totally irrelevant to most people’s day-to-day lives. One can live very well without knowledge of Newtonian mechanics, cell theory and DNA, and other sciences. On the other hand, science can enormously enrich one’s life, and in modern society knowledge is essential for innumerable policy decisions that affect our lives (see Chapters 8 and 9).

  A formal description of what may be regarded as common sense comes from the American psychologist George Kelly, who has developed what is known as Personal Construct Theory. Central to this theory about the way in which people arrange their knowledge of the world in their everyday life is the idea that they organize information in such a way as to predict future events. Common-sense theories provide mental models of the way in which the everyday world works. People check how much sense they make of the world by seeing how well their model serves them in predicting what will happen. The constructions they place upon events are their working hypotheses which are tested against experience. A person may employ a variety of constructs, some of which may be incompatible with one another, although they are not recognized by that person as being so. Thus at a very low level we may be thought to be doing ‘science’ in our everyday life by setting up hypotheses and testing them against experience. Cooking is a typical example, since one does experiment; but this is not science since there is no need for theory – only imaginative trial and error is required to achieve the right ‘taste’. Doing science, on the other hand, requires one to remove oneself from one’s personal experience and to try to understand phenomena not directly affecting one’s day-to-day life, one’s personal constructs. In everyday life, one requires no construct as to why bodies fall when dropped or why children may or may not resemble their parents; it is sufficient that they do so. Common sense provides no more than some of the raw material required for scientific thinking.

  At its simplest most human actions involve forming a goal and modifying one’s actions in order to achieve the goal. The value of this simplified model is that it emphasizes the common-sense nature of our behaviour and what we were designed for. The model requires no science as such, and that is why early technology could be so successful. Another feature of this scheme is that precision, accuracy and completeness of knowledge are seldom required – quite unlike science. We make decisions based upon what is in our memory – a memory that is, as will be seen, biased toward overgeneralization of the commonplace and overemphasis on the discrepant or rare cases.

  Whereas scientific theories may be judged in terms of their scope, parsimony – the fewer assumptions and laws the better – clarity, logical consistency, precision, testability, empirical support and fruitfulness, lay theories are concerned with only a few of these criteria and are seldom explicit or formal, or consistent, and are often ambiguous. The explicit or formal nature of scientific theories is not only important in its own right but points to a crucial feature of the scientific process: the self-aware nature of the endeavour. This self-aware aspect of doing science, as distinct from other activities, makes science different from common sense almost by definition, since, again almost by definition, common sense is unconscious. The scientist is always aware of ‘doing science’, and with that self-awareness go a number of assumptions which are seldom made explicit. They include some of the characteristics of science listed above but also include ideas that put a high value on elegance and generality (Chapter 6).

  Objectivity as distinct from subjectivity is a conventional means of characterizing scientific thinking. It is important – indeed essential – to separate evidence from theory and also to be able to look objectively at a theory, to recognize it as something on its own. But the idea of scientific objectivity has only limited value, for the way in which scientific ideas are generated can be highly subjective, and scientists will defend their views vigorously. Being objective is crucial in science when it comes to judging whether subjective views are correct or not. One has to be prepared to change one’s views in the face of evidence, objective information. It is, however, an illusion to think that scientists are unemotional in their attachment to their scientific views (Chapter 5): they may fail to give them up even in the face of evidence against them. Another crucial difference from common-sense or lay theories is that scientific theories involve a continual interplay with other scientists and previously acquired knowledge for scientific ideas are directed not just at a particular phenomenon in everyday life but at finding a common explanation for all the relevant phenomena, and an explanation which other scientists would accept.

  Associated with lay theories is a tendency to adapt and modify the theory too hastily in relation to the way people live, because people want to believe in a just and more or less ordered world over which they have some control. Many conclusions are influenced by the emotional content of the data. Bertrand Russell proposed that ‘popular induction depends upon the emotional interest
of the instances, not upon their number.’ Examples of this abound in everyday life. Suppose that, via consumer reports and your local and trusted garage, you have carefully researched what car to buy and have settled on model X. And then you meet a close colleague and tell him of your decision. If he then reacts with shock and relates his own terrible experience with car X, listing all the problems he had, would you really be unaffected? Even though his account is but one in a large number, you will have great difficulty ignoring his advice.

  Research into how people reason about complex issues of genuine importance such as crime and unemployment again emphasizes the difference between common-sense thinking and more formal scientific thinking. At the extremes there are two very different attitudes towards knowledge. One pole is the comfortable ignorance of never having considered that things could be otherwise; the other is a continual self-aware evaluation of the evidence and subsequent modification of views. These reflect the distinction between knowing something to be true and contemplating whether one believes it to be true or not. Only a minority (about 15 per cent) appear to have the latter capacity but scientists – even though they may not like to – have to adopt this approach.

  The processes by which we make deductions in everyday life, such as about the cause of a particular event, are often carried out by processes of which we are unaware. Such processes are poorly understood, and it is notoriously difficult to mimic ‘common sense’ on a computer. For example, if you leave your house one morning and notice that the grass is wet, you are almost sure it rained during the night. But if you then learn that the sprinkler was left on all night, your confidence in the ‘rain hypothesis’ is greatly diminished. It is hard to program this into a computer. The psychologist Johnson-Laird claims that common-sense thinking is based neither on formal logical rules for inference nor on rules that contain specific knowledge. It seems that the way we reach valid conclusions from a set of premisses is to construct mental models. The mind then can manipulate the model it has produced and try out various alternatives. Conclusions can be drawn from the model which can then be tested. Consider the following problem, which is hard to solve by common-sense thinking. In a room of archaeologists, biologists and chess-players, if none of the archaeologists is a biologist and all the biologists are chess-players, what inferences can be drawn? One can try various models to see which inference can be made, rather than proceed by formal logic. The only correct inference is that ‘Some chess-players are not archaeologists.’ This case shows how difficult formal reasoning can be.