apa itu ilmu karya Chalmers
Science as knowledge derived from
The facts of experience
A widely held commonsense view of science
In the introduction I ventured the suggestion that a popular conception of the distinctive feature of scientific knowledge is captured by slogan “science is derived from the facts”. In the first four chapters of this book this view is subjected to a critical scrutiny. We will find that much of what is typically taken to be implied by the slogan cannot be defended. Nevertheless, we will find that the slogan is not entirely misguided and I will attempt to formulate a defensible version of it.
When it is claimed that science is special because it is based on the facts, the facts are presumed to be claims about the world that can be directly established by a careful, unprejudiced use of the senses. Science is to be based on what we can see, hear and touch rather than on personal opinions or speculative imaginings. If observation of the world is carried out in a careful, unprejudiced way then the facts established in this way will constitute a secure, objective basis for science. If, further, the reasoning that takes us from this factual basis to the laws and theories that constitute scientific knowledge is sound, then the resulting knowledge can itself be taken to be securely established and objective.
The above remarks are the bare bones of a familiar story that is reflected in a wide range of literature about science. “science is a structure built upon facts” writes J. J. Davies (1968, p. 8) in book on the scientific method, a theme elaborated on by H. D. Anthony (1948, p.145):
It was not so much the observations and experiments which Galileo made that caused the break with tradition as his attitude to them. For him, the facts based on them were taken as facts, and not related to some prococeived idea…. The facts of observation might, or might not, fit into an acknowledged scheme of the universe, but the important thing, in Galileo’s opinion, was to accept the facts and build the theory to fit them.
Anthony here not only gives clear expression to the view that scientific knowledge is based on the facts established by observation and experiment, but also gives a historical twist to the idea, and he is by no means alone in this. An influential claim is that, as a matter of historical facts, modern science was born in the early seventeenth century when the strategy of taking the facts of observation seriously as the basis for science was first seriously adopted. It is held by those who embrace and exploit this story about the birth of science that prior to the seventeenth century the observable facts were not taken seriously as the foundation for knowledge. Rather, so the familiar story goes, knowledge was based largely on authority, especially the authority of the philosopher Aristotle and the authority of the bible. it was only when this authority was challenged by an appeal to experience, by pioneers of the possible. The following account of the oft-told story of Galileo and the Leaning Tower of Pisa, taken from Rowbotham (1918, pp.27-9), nicely captures the idea.
Galileo’s first trial of strength with the university professors was connected with his researches into the laws of motion as illustrated by falling bodies was regulated by their respective weights: thus, a stone weighing only a single pound and so on. No one seems to have questioned the correctness of this rule, until Galileo gave it his denial. He declared that weight had nothing to do with the matter and that ….. two bodies of unequal weight …. Would reach the ground at the same moment. As Galileo’s statement was flouted by the body of professors, he determined to put it to a public test. So he invited the whole university to witness the experiment which he was about to perform from the leaning tower. On the morning of the day fixed, Galileo, in the presence of the assembled university and townsfolk, mounted to the top the tower, carrying with him two balls, one weighing one hundred pounds and the other weighing one pound. Balancing the balls carefully on the edge of the parapet, he rolled them over together; they were seen to fall evenly, and the next instant, with a load clang, they struck the ground together. The old tradition was false, and modern science, in the person of the young discoverer, had vindicated her position.
Two schools of thought that involve attempts to formalize what I have called a common view of science, that scientific knowledge is derived from the fact, are the empiricists and the positivists. The british empiricists of the seventeenth and eighteenth centuries, notably John Locke, George Berkeley , and David Hume, held that all knowledge should be derived from ideas implanted in the mind by way of sense perception. The positivists had a somewhat broader and less psychologically orientated view of what facts amount to, but shared the view of the empiricists that knowledge should be derived from the facts of experience. The logical positivists, a school of philosophy that originated in Vienna in the 1920s, took up the positivism that had been introduced by Auguste Comte in the nineteenth century and attempted to formalize it, paying close attention to the logical form of the relationship between scientific knowledge should in some way be common view that scientific knowledge should in some way be derived from the facts arrived at by observation.
There are two rather distinct issues involved in the claim that science is derived from the facts. One concerns the nature of these ‘facts” and how scientist are meant to have access to them. The second concerns how the laws and theories that constitute our knowledge are derived from the facts once they have been obtained. We will investigate these two issues in turn, devoting this and the next two chapters to a discussion of the nature of the facts on which science is alleged to be based and chapter 4 to the question of how scientific knowledge might be thought to be derived from them.
There components of the stand on the facts assumed to be the basis of science in the common view can be distinguished they are:
(a) facts are directly given to careful, unprejudiced observers via the senses.
(b) Facts are prior to and independent of theory.
(c) Facts constitute a firm and reliable foundation for scientific knowledge.
As we shall see, each of these claims is faced with difficulties and, at best, can only be accepted in a highly qualified form.
Seeing is believing
Partly because the sense of sight is sense most extensively used to observe the world, and partly for convenience, I will restrict my discussion of observation to the realm of seeing, in most cases, it will not be difficult to see how the argument presented could be re-cast so as to be applicable to the other senses. A simple account of seeing might run as follows. Humans see using their eyes. The most important components of the human eye are a lens and retina, the latter acting as a screen on which images of objects external to the eye are formed by the lens. Rays of light from a viewed object pass from the object to the lens via the intervening medium. These rays are refracted by the material of the lens in such a way that they are brought to a focus on the retina, so forming an image of the object. Thus far, the functioning of the way the final image is recorded. Optic nerves pass from the retina to the central cortex of the brain. These carry information concerning he light striking the various regions of the retina. It is the recording of this information by the brain that constitutes the seeing of the object by the human observer. Of course, many details could be added to this simplified description, but the account offered captures the general idea.
Two points are strongly suggested by the forgoing account of observation through the sense of sight that are incorporated into the common or empiricist view of science. The first is that a human observer has more or less direct access to knowledge of some facts about the world insofar as they are recorded by the brain in the act of seeing. The second is that two normal observers viewing the same object or scene from the same place will “see” the same thing. An identical combination of light rays will strike the eyes of each observer, will be focused on their normal retinas by their normal eye lenses and give rise to similar images. Similar information will then travel to the brain of each observer via their normal optic nerves, resulting in the two observers seeing the same thing. In subsequent sections we will see why thi kind of picture is seriously misleading.
Visual Experiences Not Determined Solely By The Object Viewed
In its starkest form, the common view has it that facts about the external world are directly given to us through the sense of sight. All we need to do is confront the world before us and record what is there to be seen. I can establish that there is a lamp on my desk or that my pencil is yellow simply by noting what is before my eyes. Such a view can be backed up by a story about how the eye works, as we have seen. If this was all there was to it, then what is seen would be determined by the nature of what is looked at, and observers would always have the same visual experiences when confronting the same scene, however, there is plenty of evidence to indicate that this is simply not the case. two normal observer viewing the same object from the same place under the same physical circumstances do not necessarily have identical visual experiences, even though the images on their respective retinas may be virtually identical. There is an important sense in which two observers need not “see” the same thing. As N.R. Hanson (1958) has put it, “there is more to seeing than meets the eyeball”. Some simple examples will illustrate the point.
Most of us, when first looking at Figure 1, see the drawing of a staircase with the upper surface of the stairs visible. But this is not the only way in which it can be seen. It can without difficulty be seen as a staircase with the under surface of the stairs visible. Further, if one looks at the picture for some time, one generally finds that what one sees changes frequently, and involuntarily, from a staircase viewed from above to one viewed from below and back again. And yet it seems reasonable to suppose that, since it remains the same object viewed by the observer, the retinal images do not change. Whether the picture is seen as a staircase viewed from above or one viewed from below seems to depend on something other than the image on the retina of viewer. I suspect that no reader of this book has questioned my claim that Figure 1 depicts a staircase. However, the results of experiments on members of African tribes whose culture does not include the custom of depicting three-dimensional objects by two-dimensional perspective drawings, nor staircases for that matter, indicate that members of those tribes would not see Figure 1 as a staircase at all. Again, it seems to follow that the perceptual experiences that individuals have in the act of seeing are not uniquely determined by the images on their retinas. Hanson (1958, chapter 1) contains some more captivating example that illustrate this point.
Another instance is provided by children’s picture puzzle that involves finding the drawing of a human face among the foliage in the drawing of a tree. Here, what is seen. That is, the subjective impressions experienced by a person viewing the drawing, at first corresponds to a tree, with trunk, branches and leaves. But this changes once the human face has been detected. What was once seen as branches and leaves is now seen as a human face. Again, the same physical object is viewed before and after the solution of the puzzle, and presumably the image on the observer’s retina does not change at the moment the puzzle is solved and the face found. If the picture is viewed at some later time, the face is readily and quickly seen by an observer who has already solved the puzzle once. It would seem that there is a sense in which what an observer sees is affected by his or her past experience.
“What”, it might well be suggested, “have these contrived examples got to do with science?” in response, it is not difficult to produce examples from the practice of science that illustrate the same point, namely, that what observers see, the subjective experiences that they undergo, when viewing an object or scene is not determined solely by the images on their retinas but depends also on the experience, knowledge and expectations of the observer. The point is implicit in the uncontroversial realization that one has to learn to be a competent observer in science. Anyone who has been through the experience of having to learn to see through a microscope will need no convincing of this. When the beginner looks at a slide prepared by an instructor through a microscope it is rare that the appropriate cell structures can be discerned, even though the instructor has no difficulty discerning them when looking at the same slide through the same microscope. It is significant to note, in this context, that microscope found no great difficulty observing cells divide in suitably prepared circumstances once they were alert for what to look for, whereas prior to this discovery these cell divisions went unobserved, although we now know they must have been there to be observed in many of the samples examined through a microscope. Michael Polanyi (1973, p. 101) describes the changes in medical student’s perceptual experience when he is taught to make a diagnosis by inspecting an X-ray picture.