Speed (1991) defines realism in a succinct, yet informative way as"the position that reality exists, can be discovered by people in an objective wayand thus determines what we know." This definition contains two explicit tenets andone implicit tenet held by many realists:

• A reality exists independent of the observer (Speed, 1991; Casti, 1989).
• This reality can be discovered and understood exactly as it is (Held, 1990; Chalmers, 1976).
• This reality can be experienced and shared by everyone in precisely the same way (Osborne, 1996; Chalmers, 1976).

    Outside the mind of humans there exists an independent reality(Matthews, 1994; Yarusso, 1992; Speed, 1991). Reality is not altered by human perception,thought, or interaction (Osborne, 1996; Matthews, 1994; Klemke, et al., 1980). It iscomposed of absolute truths that are inflexible (Matthews, 1994). This reality can bediscovered by any cognizant being with the capacity to understand it. Reality and allknowledge of it is revealed to, not invented by, the observer. As Yarusso (1992) statesit, "The key (realist) position is that there is an external reality that is,ultimately, accessible to the human mind." Reality can be perceived objectively."In a perfect world, we would all have the same interpretation of what is true, whatis right, what is false, and what is wrong" (Yarusso, 1992). This information, theseinexorable discoveries and facts about the universe, once unearthed, can be taught to, orlearned by, others in a way that will allow their being transferred without alteration ofmeaning. Since "external reality is, ultimately, accessible to the human mind,"it follows that those capable would perceive it in exactly the same way. With some effort,every human (or sentient being for that matter), could understand the same informationabout the universe in exactly the same way since that information can be discoveredobjectively and with the same interpretation.

    One realist’s view is humorously summed up in the followingpoem from Chemistry for Changing Times (7th Ed.) by Hill, J. W. & Kolb, D. K.(1992).

    The term "constructivism" has been used so extensively bysuch a large number of people and for a wide variety of purposes that there is almost noconsensus as to its actual meaning (Phillips, 1995). There are, however, several elementsof these theories that Phillips identified and assembled into a three dimensional"framework for comparing constructivisms". In this framework, each axisrepresents a major component of constructivism.

    The first axis discussed is labeled "individual psychologyverses public discipline". On one extreme of this axis are the researchers concernedonly with the individual and how (s)he constructs knowledge (ex. Phillips, Piaget,Vygotsky). On the other extreme are those unconcerned with the individual, but consumed bythe idea of "the construction of human knowledge in general" (ex. Acoff, Barnes,Bloor, Collins, Potter). This is the social constructivist view. In the middle ground arephilosophers such as von Glasersfeld, Popper, Kant; concerned both with the individual andthe society.

    The second axis is "humans the creator versus nature theinstructor". This addresses the issue of whether knowledge is constructed "...bythe mind or creative intelligence of the knower..." or is "imposed from theoutside" and the human mind is nothing more than an empty basket awaiting facts andknowledge to fill it. The views of Ernst von Glasersfeld represent the former while thoseof John Locke are a good example of the latter. The comparison of constructivist’sideas now begins to become somewhat convoluted because not all (it seems very few) agreewhen these two axes are combined. Two researchers may agree on one topic yet bediametrically opposed on the other. This convolution is increased when the third dimensionis added.

    The third axis is "physical activity versus mentalactivity". At one extreme it is believed that only by doing, by being physicallyactive, can knowledge be constructed. The other extreme views knowledge construction as amental process only. Most of the constructivists mentioned in this work fall somewhere inthe middle ground believing that knowledge is constructed by a combination of physical andmental activities.

    A review of these axes demonstrates that many combinations ofconvictions can be held and still considered constructivist (Phillips, 1995). For purposesof this paper I will hold three of the more conventional constructivist components:

• Knowledge is constructed by the individual and/or society.
• A reality exists independent of the observer, but the question of what it objectively is like is unanswerable at best.
• A scientific theory is a good theory if it is useful in making predictions that fit the impressions of reality.

    Let us now compare and contrast the two epistemologies in questionwith each of the five general components of the nature of science. During this analysis,several natures of science components are considered at once. The history and philosophyof science, because of their close association (Matthews, 1994), and the two componentsaddressing how the scientist actually performs science are discussed simultaneously (Kuhn,1970). Finally, the goals of science are addressed separately.

    Throughout recorded history, humans have created or inventedexplanations for observed natural phenomena. In some cases this led to the invention ofmagical beliefs, myths, or religions (Campbell, 1988). In other cases this led to morescientific explanations. These explanations were tested by whatever means the cultureeither deemed appropriate or had the technological ability to confirm. Support for thesetheories was, therefore, at the mercy of cultural biases and technologies (Matthews,1994). In some cases the culture did not value or practice confirmation in any modernsense. Quoting authority, saving the appearances, and/or argument were all that wasrequired to keep many explanations viable for years (Campbell, 1988).

    When a more powerful* theory emerged, theold theory was amended to incorporate the new. Often if the competing theories wereincompatible, the new completely replaced the old in a "revolution" of some kind(Matthews, 1994; Wallace, 1989; Richards, 1987; Kuhn, 1970). History is teeming withexamples of theories that have been replaced or modified: Aristotle’s fourfundamental elements and his crystal spheres, Hipparchus’ geocentric universe,Newton’s absolute space and time, Hoyle’s steady state theory of the universe(Hawking, 1988; Hoyle, 1962).

    The strong realist view would have us believe that once the truth isknown, no further changes need ever be made. After the answer to the question has beenfound, what is the purpose of further investigations? (Matthews, 1994). The reader isasked to remember Speed’s definition of realism, "...that reality exists (and)can be discovered by people in an objective way...". This objective reality, onceknown, can be experienced and shared precisely as it is.

    Aristotle’s crystal spheres and Hipparchus’ geocentricuniverse were considered truth by the human race for far longer than the presentlyaccepted theories. Who is to say that what is presently considered scientifically soundwill remain so in the future? Has not history taught us humility about our ability todiscover the ultimate truth? As was so concisely expressed by Carl Sagan "...claimsof ultimate truth we (meaning scientists, author’s inset) leave to politicsand religion" (Sagan, 1980).

    The reader might realize that this is also an argument for anotherset of components under consideration: How the scientist discovers or invents patterns andexplanations for those patterns. These can be lightheartedly paraphrased as, "What doscientists actually do?".

    One function of the modern scientist is to explain and makepredictions concerning natural phenomena (Medawar, 1982; Kuhn, 1970). One recent exampleof this is geologist’s attempts to explain why earthquakes and volcanoes occur. Forcenturies it was known by some societies as a "fact" that these two events wereunrelated. The former were known to be caused by huge animals moving underground while thelater were seen as proof of the existence for a fiery underworld for wrongdoers (Thompson& Turk, 1991; Campbell, 1988).

    Over the centuries many different societies invented explanationsfor these two disparate events. The citizens of these societies went about their dailylives in relative comfort knowing these questions had been put to rest. But not everyonewas satisfied with the accepted explanations.

    In 1912, Alfred Wegener published his theory of Continental Drift.Bitter debates ensued. After a short time, geophysicists defeated a major component of thetheory. It was correctly demonstrated that Wegener’s explanation for his proposedcontinental movement was wrong. He suggested for the mechanism causing this drifting thegravitational influence of the Sun and Moon on the Earth. This gravitational force wascalculated to be far too weak to move the continents (Thompson & Turk, 1991; Leet& Judson, 1971).

    During the following decades many other geologists including Hess,Vine, Matthews, and Lawrence investigated, altered, and revised Wegener’s initialtheory into the presently generally accepted form of plate tectonics (Thompson & Turk,1991). This theory elegantly draws together volcanism, earthquakes, mountain building andother once separate events into a single entity. But is this the ultimate truth? Have allof the questions been answered?

    How did the scientists in this example construct their newesttheory? They improved their equipment and observations. They made serendipitous finds.They made and then tested predictions. They debated and discussed with each other. Whenpossible they went to locations and investigated. When it was not possible to visit a sitefor first hand experience, existing equipment was modified or new equipment was inventedthat extended their senses (e.g. sonar). Many different scientists performed manydifferent types of investigations. Not everyone followed the same steps. There is no oneway to do science. There is no one scientific method (Millar, 1989).

    Modern scientific theories are held to rigorous standards. They mustbe internally consistent. They must agree with observable phenomena. They must makepredictions that can be tested. Tests must be repeatable by others (Rhodes & Schaible,1989; Trusted, 1979; Kuhn, 1970).

    Theories are considered by the strong realist scientists to beapproximations of an absolute knowledge that is ultimately attainable precisely andobjectively by the mind of man. The first half of this last statement should cause nocontroversy between realists and some constructivists. As the reader will remember fromthe description of the constructivist theories, some also maintain that their theoriesactually approximate a reality. They would argue, however, that this reality can never beobjectively known since all of the perceptions of the outside world are filtered throughexperiences (Matthews, 1994) and assimilated into existing cognitive structures(Wadsworth, 1996). As the individual tries to fit (assimilate) these impressions from thesenses into existing structures, it is often the impressions, not the structures that arealtered (Wadsworth, 1996). Also, to many constructivists it is not whether the theory isactually true, for theories can never be proven (Kuhn, 1970). What is of interest is howwell the theory in question works; how well it enables one to cope.

    For the present, the theory of plate tectonics works well inexplaining why many geological features are as they seem. But it is not a completedtheory. There is much it can not do. For example, it can predict where earthquakes aremore likely to occur (ex. California). It can not predict with absolute accuracy when andwhere earthquakes caused by strike-slip faults will occur nor how destructive they willbe. It can explain why many volcanoes exist around the Eastern Rim. It can not predictwith perfect accuracy when or where a subduction zone induced volcano will erupt. We donot yet know reality absolutely.

    The three general constructivist factors being discussed match thescientists' behavior quite well:

• The data provided them by their senses must be fitted with existing knowledge or either the existing knowledge or the new data must change.
• It is not possible to know if the current theory is a true explanation for those data.
• As long as the theory makes reliable predictions it is useful. When it ceases to be useful it must be revised or abandoned.

And what of the last component of the nature of science, the goals of science?

    As for the realist notion that the goal of science is to discoverexactly what nature is and how it works, Jacob Bronowski in his book The Assent of Man(1973) remarked, "One aim of the physical sciences has been to give an exact pictureof the material world. One achievement of physics in the twentieth century has been toprove that that aim is unattainable" (Bronowski, 1973).

    This comment was made with reference to quantum theory and inparticular the Heisenberg Uncertainty Principle. This principle demands that there is alimit to the amount of accurate information it is possible to obtain about subatomicparticles. The more accurately one measures, for example, the position of a particle, theless accurately one knows its momentum (Giancoli, 1991). When humans attempt to measurethese particles, the measurement process itself changes them. Our attempt to understandnature actually alters it. Whether there is a reality independent of the observer or not,there is a limit to the amount and accuracy of that which is knowable by that observer.All information about nature can not be known precisely (Elkana, 1970).

    The philosophical implications of this principle have long beenknown. To quote a prolific science writer:

"Philosophically, this is an upsetting doctrine. Ever since the time of Newton,scientists and many nonscientists had felt that the methods of science, in principle atleast, could make measurements that were precise without limits. One needed to take onlyenough time and trouble, and one could determine the nth decimal place. To be toldthat this was not so, but that there was a permanent wall in the way of total knowledge, awall built by the inherent nature of the universe itself, was distressing" (Asimov,1966).

    With the goal of ultimately discovering nature objectively dashed, arealist might argue that this itself is understanding the truth about nature. An ugly andconfusing argument that would be: The ultimate reality of the universe is that humans cannever know reality precisely. How do we know that the universe does not function in such away as to prohibit our minds from ever understanding it precisely? Since the human mind ispart of the universe and presumably follows its laws, it must also be a part ofprohibiting itself from the knowledge that it seeks!

    This is a clear advantage for a major component of manyconstructivist theories: Human knowledge must always be incomplete. Our actions taint theresults hence the conclusions we draw from them. Our actions influence what we can and doknow about reality. This says nothing about the existence of an independent reality, onlyour ability to precisely know and copy it.

"There is no absolute knowledge, and those who claim it, whether they arescientists or dogmatists, open the door to tragedy. All information is imperfect. We haveto treat it with humility. That is the human condition ..." (Bronowski, 1973).

Or to quote one of the most revolutionary and prolific researchers in developmentalconstructivism, "Knowledge is not a copy of reality" (Piaget, 1964).

    To review three of the most powerful arguments constructivists usewhen debating realists on this topic (as discussed in Matthews, 1994):

1. The history of science is replete with abandoned and disproved theoretical entitiesthat earlier were firmly ensconced in the best science of their time. (What is accepted asfact today may be discredited tomorrow.)

2. Theoretical provisions are always limited by the amount of evidence available, andconsequently the same evidence will also support other existing or potential, theoreticalentities. (Theories can never be proven. A good theory is a useful theory. There are oftenmore than one theory that will fit the existing data.)

3. Scientific conceptions are determined by the theory in which they occur as well asby the reality they purportedly describe. (If our knowledge of reality is ultimatelyimperfect and incomplete, so must be our theories of reality.)

    "The study of science as an intellectual and social endeavor -the application of human intelligence to figuring out how the world works - should have aprominent place in any curriculum that has science literacy as one of its aims"(Rutherford, et al., 1993).

    In the previous section I argued that some elements ofconstructivist epistemologies more closely approximate components of the nature ofscience. Having done this, how can this information be used? What are some implicationsfor a science education curriculum?

    One implication is obvious; science courses should not be taught asa list of known facts to be memorized. How does the teacher know what facts will still beconsidered as such in the years to come? How can the teacher be sure of what each andevery student will need to know in the coming decades? To quote from the popular andinfluential book, National Science Education Standards, "In learning science,students need to understand that science reflects its history and is an ongoing, changingenterprise" (National Research Council, 1996). Science must be seen as a dynamic nota static endeavor.

    Another implication is that the students should be engaged in realinvestigations (National Research Council, 1996). They should be challenged to createtheir own problems and solutions (Elkana, 1970). These solutions should then be challengedand tested. The students should be given the freedom to work creatively on projects oftheir own interest (Phillips, 1994). "Experiments" should not be simply show andtell nor exercises in following directions (Phillips, 1994). They should be realisticexamples of how science is done.

    "Since a key principle of education is to begin with what thelearner already knows, finding this out is a very important initial step in anyeducational endeavor (Novak & Gowin, 1984)." This quotation illustrates a thirdimplication one can gather from a constructivist epistemology: No student (or scientistfor that matter) begins an investigation with a clean slate. That is to say, all studentslikely have some prior knowledge or ideas about what is to be investigated (Rauff, 1994).Students will either assimilate new data into existing structures or accommodatethemselves to these new data (Wadsworth, 1996). An instructor working to further eachstudent’s development should be aware that every individual in the class is bringingpast experiences that taint present thinking. The instructor needs to question thestudent, learn some of these preconceptions, and then help to steer the student in adirection that will lead to growth* .

    Science education needs to be more than a study of known orpresently believed facts, laws, and theories. It needs to be more than a history courseinto science’s past or a study of the philosophy, sociology, or psychology ofscience. To quote from Benchmarks for Science Literacy:

    "Acquiring scientific knowledge about how the world works doesnot necessarily lead to an understanding of how science itself works, and neither doesknowledge of the philosophy and sociology of science alone lead to a scientificunderstanding of the world" (Rutherford, et al., 1993).

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