NATURE AND LIMITS OF SCIENTIFIC KNOWLEDGE AND …



NATURE OF SCIENTIFIC KNOWLEDGE AND SCIENTIFIC METHODOLOGY.

(This text is adapted from first chapter of “Science for all Americans. Project 2061 of American Association for the Advancement of Science. (1990) Oxford University Press. New York, NY.)

Over the course of history, we have attempted to understand ourselves, our environment, and our role in the environment. To do so we use different “ways of knowing about our world including scientific knowledge, societal knowledge, religious knowledge, and cultural knowledge. Science differs from these other ways of knowing in important ways.”(2)

Science is a way of knowing about the physical and biological worlds. “People have developed many interconnected and validated ideas about these worlds. Those ideas have enabled successive generations of humans to achieve an increasingly comprehensive and reliable understanding of the human species and its environment. The means used to develop these ideas are particular ways of observing, thinking, experimenting, and validating. These ways represent a fundamental aspect of the nature of science and reflect how science tends to differ from other modes of knowing.”(1)

This chapter on the Nature of Science focuses on three areas: the scientific world view, the scientific method, and the nature of the scientific enterprise. [The numbered statements printed in italics are the specific ‘Nature-of-Science’ objectives of the Natural World LADR.]

THE SCIENTIFIC WORLD VIEW.

Science is a way of knowing of ourselves and of the world (universe) in which we live. This is, we can understand or explain how the many functions of our body and environment work (e.g., the blood circulates because the heart pumps the blood around, predict the movement of earth, planets, and sun, and can predict the inheritance of genes, or explain how genetic material is carefully divided over to daughter cells during cellular reproduction.) We express our knowledge or understanding of a function or activity by describing the underlying mechanism. When our understanding involves very fundamental areas of our bodies or of the universe our knowledge is set out in theories (e.g., the theory of plate tectonics, the relativity theory, and the evolution theory) or is summarized in laws (e.g., law of gravity, law of thermodynamics) or dogma e.g., the central dogma in molecular biology).

Note that in science a theory is a very fundamental explanation that affects a wide range of aspects of the world. Also, the meaning of the word theory in science (a body of knowledge that explains with considerable certainty large sets of activities of the world. A theory is held with a high degree of confidence and is supported by enough evidence to make its abandonment unlikely) is different from that of the vernacular English usage(one of several speculative explanations of an activity, that is, a hunch or a guess). Similarly, scientists use the word “dogma” (a summary statement of a very fundamental understanding of the world) differently from its vernacular usage (an immutable truth).

Examples of scientific theories (2):

a) Atomic theory: The atom is the smallest unit of matter. The atom is composed of the nucleus in the middle of the atom that is composed of neutrons, protons, (both of these may break down in smaller particles). The neutrons have no charge. The protons have a positive charge. The electrons swirl around the nucleus in a large region, rather than orbiting in affixed pattern (electron cloud). The electrons have a negative charge.

b) Big Bang theory: The Big Bang Theory assumes that the universe began from a singular state of infinite density and started expanding from an explosive moment of creation. The theory was further developed in the 1940s by George Gamow and R.A. Alpher. Fred Hoyle coined the term Big Bang. The Big Bang theory is the dominant scientific theory about the origin of the universe. According to the theory, the universe was created sometime between 10 billion and 20 billion years ago from a cosmic explosion that hurled matter in all directions.

c) Gravity theory: Gravity is a force that attracts objects in the universe. The most familiar of the four fundamental interactions of matter, gravitation has several characteristics that distinguish it from the other interactions. (1) It is universal, (2) it is always attractive, (3) it is a long-range interaction, and (4) it affects all matter.

d) Evolution theory: Evolution theory states that all living things are related to one another through common ancestry from earlier forms that differed from the present form. Biologists agree that all living things arose through a long history of changes shaped by physical, chemical processes that are still taking place. Variability among individuals of a population of sexually reproducing organisms is produced by mutation and genetic recombination. The resulting genetic variability is subject to natural selection in the environment.

e) Cell theory: (1) All living material is organized in cells. (2) All cells are derived from previously existing cells (most cells arise by cell division, but in sexual organisms they may be formed by the fusion of gametes. (3) The cell is the most elementary unit of life. Every cell is bound by a plasma membrane that separates it from the environment and from other cells.

f) Germ theory of Disease: Louis Pasteur argued that infectious diseases are caused by germs. The germ theory has affected our views on infectious diseases, surgery, hospital management, agriculture, and industry.

g) Special Relativity theory. Albert Einstein’s theory of Special Relativity, published 1905, revealed that energy and matter are different manifestations of the same phenomenon and can be transformed into each other in terms of the relationship E=mc2.

h) General Relativity Theory. Einstein’s General Relativity Theory (1917) provided a powerful new way to view gravity as a warping of the four-dimensional space-time continuum by the presence of matter. If space-time is imagined as a rubber sheet, then massive objects such as stars and galaxies create deformations in space-time, just as a bowling bowl sitting on a mattress creates a dent into which nearby smaller objects fall. Thus the shape of space-time determines the behavior of matter/energy. At the same time, the presence of matter/energy determines the shape of space-time.

i) Plate Tectonics theory: Plate tectonics is an all-embracing theory that the crust of the earth is divided into a number of rigid plates floating on a viscous underlayer of the mantle. Alfred L. Wegener was the first to propose (1912) that the continents were at one time connected and had drifted apart. In 1960 when H. H. Hess suggested that new ocean floor was created at the mid-oceanic ridges and the ocean evolved by seafloor spreading.

j) Quantum Theory: This theory says that energy exist in tiny discrete units called quanta. Quantum theory shows how atomic particles such as electrons may also be seen as having wave-like properties. Quantum theory is the basis of particle physics, modern theoretical chemistry, and the solid-state physics that describes the behavior of the silicon chips used in computers. Quantum theory and the theory of relativity together form the theoretical basis of modern physics. Later work by scientists elaborated the theory into what is called quantum mechanics (or wave mechanics).

k) Unified Field Theory: This theory proposes to unify the four known interactions or forces (the strong, electromagnetic, weak, and gravitational forces) by a simple set of general laws. These four forces control all the observed interactions in matter: gravitation, electromagnetism, the strong force tat holds atomic nuclei together, and the weak force (force present in some nuclear processes).

The world is understandable:

In its attempt to understand the world, science assumes (a) the existence of an external reality (the world or the universe), and (b) the uniformity of nature, i.e., that natural processes operate in a fairly consistent manner (this is the basis for the idea of natural laws). (3) Thus, science assumes that the world (universe) around us is real and independent of human perception (philosophers use the word objective) and that we can know that reality, i.e., that it is not part of or colored by our individual imaginations. (Note that not all philosophers of science agree with this last assumption.)

“Secondly, science presumes that the things and events in the universe occur in consistent patterns that are comprehensible through careful, systematic study. Scientists believe that through the use of the intellect, and with the aid of instruments that extend the senses, people can discover patterns in all of nature.”(1) Thus, the testimonial of Leon Lederman (Director emeritus of Fermi National Accelerator Laboratory) in the closing words of his essay: “And underlying it all, the sense of wonder that nature is comprehensible.” (5)

“Science assumes that the universe is, as its name implies, a vast single system in which the basic rules are everywhere the same. Knowledge gained from studying one part of the universe is applicable to other parts. For instance, the same principles of motion and gravitation that explain the motion of falling objects on the surface of the earth also explain the motion of the moon and the planets. With some modifications over the years, the same principles of motion have applied to other forces – and to the motion of everything, from the smallest nuclear particles to the most massive stars, from sailboats to space vehicles, from bullets to light rays.”(1)

The tools used to discover the consistent patterns of nature form the scientific method. You will learn more about this in the second leg of this chapter.

1. Articulate a central assumption of science: the universe is real and operates according to universally consistent rules, and we can discover these rules by logical thought subject to test through experiments and observations.

Application:

a) The two laws of (simple) Mendelian inheritance of traits describe the universally consistent ways by which the traits of peas (and of all diploid organisms) are inherited. Mendel discovered these ways by careful observation and experimentation and by thinking of a model that explained all the observations (or results of the experimental crosses between the peas).

b) Similarly, we can summarize the structure of organic molecules, of nucleotides, and DNA because we have discovered the ‘universally consistent rules’ by which these molecules are made up. The DNA of the bacterium Escherichia has the same basic structure as the DNA of a mouse or a human.

c) That the universe occurs in consistent patterns is also reflected in the fact that DNA is the genetic material (except in RNA viruses where RNA is the genetic material) of all living organisms.

d) Similarly, the molecular linkage between the genes (information) and the traits (phenotype, realization of the genes in the individual) is in all living organisms expressed by the flow of information from DNA to RNA to protein, i.e., the Central Dogma.

Scientific ideas are subject to change:

“Science is a process for producing knowledge. The process depends both on making careful observations of phenomena (these include the results of experiments) and on inventing theories (constructing models) for making sense out of those observations. Change in knowledge is inevitable because new observations may challenge prevailing theories. No matter how well one theory explains a set of observations, it is possible that another theory may fit just as well or better, or may fit a still wider range of observations. In science, the testing and improving and occasional discarding of theories, whether new or old, go on all the time. Scientists assume that even if there is no way to secure complete and absolute truth, increasingly accurate approximations can be made to account for the world and how it works.”(1).

2. Explain why no scientific knowledge is considered to be absolutely and completely true, and be able to give examples of how science has historically improved, discarded, and replaced theories by experiments and observations.

Application:

a) Before Mendelian genetics explained the inheritance of traits, the ongoing ‘theory’ (or model) by which people explained the observed mode of inheritance of traits was that of pangenesis. Remember, pangenesis proposes that information from all parts, structures, and organs of the body are continually collected in the germ cells and passed on to the offspring. This theory or model of the mode of inheritance of traits was replaced by the laws of Mendel which explained more completely the observed mode of inheritance of traits and linked this knowledge to the current understanding of gametogenesis and sexual reproduction of diploid organisms.

b) The inheritance of acquired traits (Lamarckism) made perfect sense in light of pangenesis. Moreover, everyone could observe that as the newborn developed into adulthood it acquired traits that were not present or were underdeveloped at birth. Lamarckism could no longer explain the inheritance of traits, when Mendel proposed a more powerful explanation of the inheritance of traits, it became clear that acquired traits are not inherited, and people such as Weismann demonstrated this in formal lab experiments (the inheritance of short tails in mice).

c) Before the work of Chargaff, DNA of all living organisms was considered identical (a double stranded molecule of linear polymers of equal amounts of the four nucleotides) and could not explain the uniqueness of each different species. As a consequence, most molecular biologists argued that only proteins were sufficiently diverse to be the genetic material. Nevertheless, the work of Griffith and Avery and of Hershey and Chase had demonstrated differently. It is only after the careful analysis (observation) of Chargaff that the nucleotide composition of the DNA of different species is unique that most researchers agreed that DNA, not protein, was the genetic material.

Scientific knowledge is durable:

The idea that scientific knowledge is subject to change may lead to the suggestion that we never know anything (with any certainty). That is, the knowledge that we have of ourselves and our world is, at best, very tentative, and is likely going to change as new information or knowledge emerges. Of course, this is not correct. Quite a bit of what we have learned in the physical and biological sciences has ‘stood the test of time’ and is ‘known’. Moreover, it has been the basis of our ever expanding understanding of the universe.

“Although scientists reject the notion of attaining absolute truth and accept some uncertainty as part of nature, most scientific knowledge is durable. The modification of ideas, rather than their outright rejection, is the norm in science, as powerful constructs tend to survive and grow more precise and to become widely accepted. For example, in formulating the theory of relativity, Albert Einstein did not discard the Newtonian laws of motion but rather showed them to be only an approximation of limited application within a more general concept. (NASA uses Newtonian mechanics, for instance, in calculating satellite trajectories.) Moreover, the growing ability of scientists to make accurate predictions about natural phenomena provides convincing evidence that we really are gaining in our understanding of how the world works. Continuity and stability are as characteristic of science as change is, and confidence is as prevalent as tentativeness.”(1)

Scientists accept that we do not yet have a complete understanding of our world and ourselves and that we may never reach that complete understanding. However, what we do know or understand seem to be realistic or relevant to the reality. Thus, it seems clear that the genetic material of all organisms (safe RNA viruses) is DNA, that the DNA is a double-stranded molecule of nucleic acid, etc. As science progresses, we seem to modify existing models of the reality rather than revolutionizing with entirely new fundamental concepts. Most modification and changes of our concepts occur at the foreground of science. For example, whereas few researchers doubt that DNA is the genetic material, models/theories of the function and interaction of different genes in cellular metabolism are actively changing as new observations are made and need to be explained.

Application:

a) Whereas initially the inheritance of all traits was explained by Mendel’s laws (independent inheritance of traits), it became soon clear that traits could be linked on the same chromosome, or that traits could become separated by crossing-over.

b) Whereas DNA replication was initially thought to be catalyzed by DNA polymerase, it took the work of others to demonstrate how a ligase was needed to link the Okazaki fragments (link a free 3’-OH group to the free 5’-P group of an existing chain), of the primase to initiate the synthesis of the new DNA strand, and of the telomerase to lengthen the template strand prior to replication.

Science cannot provide complete answers to all questions:

Most scientists include within the domain of legitimate scientific study everything known to exist or to happen in the material universe. This leaves many questions, phenomena outside the scientific domain of inquiry. Those matters that do not deal with the material universe, e.g., supernatural, ghosts, spirits, etc. are not part of science (although these matters may be of interest to scientists). Similarly, those matters that can not be addressed by the tools of scientific inquiry also can not find understanding/explanation in science (see: Scientific Inquiry).

“There are many matters that cannot usefully be examined in a scientific way. There are, for instance, beliefs that – by their very nature- cannot be proved or disproved (such as the existence of supernatural powers and beings, or the true purpose of life. See: Scientific inquiry). In other cases a scientific approach that may be valid to explain observations is likely to be rejected as irrelevant by people who hold certain beliefs (such as miracles, fortune-telling, astrology, and superstition). Nor do scientists have the means to settle issues concerning good and evil (Answers to these questions must be found in religion, philosophy, cultural ideals and other systems of beliefs.), although they can sometimes contribute to the discussion of such issues by identifying the likely consequences of particular actions, which may be helpful in weighing alternatives.”(1)

How science differs from theology:

“The demarcation between science and theology is perhaps easiest, because scientists do not invoke the supernatural to explain how the natural world works, and they do not rely on divine revelation to understand it. When early humans tried to give explanations for natural phenomena, particularly for disasters, invariably they invoked supernatural beings and forces, and even today divine revelation is as legitimate a source of truth for many pious Christians, as is science. Many scientists have religion in the best sense of the word, but scientists do not invoke supernatural causation or divine revelation.

Another feature of science that distinguishes it from theology is its openness. Religions are characterized by their relative inviolability; in revealed religions, a difference in interpretation of even a single word in the revealed founding document may lead to the origin of a new religion. This contrasts dramatically with the situation in any active field of science, where one finds different versions of almost any explanation. New conjectures are made continuously, earlier ones are refuted, and at all times considerable intellectual diversity exists. Indeed, it is by a Darwinian process of variation and selection in the formation of testing hypotheses that science advances.” (Ernst Mayer4)

Pseudoscience.

A pseudoscience is set of ideas based on theories put forth as scientific when they are not scientific. Pseudoscientists claim to base their theories on empirical evidence, and they may even use some scientific methods, though often their understanding of a controlled experiment is inadequate. Many pseudoscientists relish being able to point out the consistency of their theories with known facts or with predicted consequences, but they do not recognize that such consistency is not proof of anything. It is a necessary condition but not a sufficient condition that a good scientific theory be consistent with the facts. A theory which is contradicted by the facts is obviously not a very good scientific theory, but a theory which is consistent with the facts is not necessarily a good theory. For example, "the truth of the hypothesis that plague is due to evil spirits is not established by the correctness of the deduction that you can avoid the disease by keeping out of the reach of the evil spirits" (Beveridge 1957, 118).

Some pseudoscientific theories are based upon an authoritative text rather than observation or empirical investigation. Creationists, for example, make observations only to confirm infallible dogmas, not to discover the truth about the natural world.

Some pseudoscientific theories explain what non-believers cannot even observe, e.g. orgone energy.

Some can't be tested because they are consistent with every imaginable state of affairs in the empirical world, e.g., L. Ron Hubbard's engram theory.

Some pseudoscientific theories can't be tested because they are so vague and malleable that anything relevant can be shoehorned to fit the theory, e.g., the enneagram, iridology, the theory of multiple personality disorder, the Myers-Briggs Type Indicator®, the theories behind many New Age psychotherapies, and reflexology.

Some theories have been empirically tested and rather than being confirmed they seem either to have been falsified or to require numerous ad hoc hypotheses to sustain them, e.g., astrology, biorhythms, facilitated communication, plant perception, and ESP. Yet, despite seemingly insurmountable evidence contrary to the theories, adherents won't give them up.

Some pseudoscientific theories rely on ancient myths and legends rather than on physical evidence, even when their interpretations of those legends either requires a belief contrary to the known laws of nature or to established facts, e.g., Velikovsky's, von Däniken's, and Sitchen's theories.

Some pseudoscientific theories are supported mainly by selective use of anecdotes, intuition, and examples of confirming instances, e.g., anthropometry, aromatherapy, craniometry, graphology, metoposcopy, personology, and physiognomy.

Some pseudoscientific theories confuse metaphysical claims with empirical claims, e.g., the theories of acupuncture, alchemy, cellular memory, Lysenkoism, naturopathy, reiki, rolfing, therapeutic touch, and Ayurvedic medicine.

Some pseudoscientific theories not only confuse metaphysical claims with empirical claims, but they also maintain views that contradict known scientific laws and use ad hoc hypotheses to explain their belief, e.g., homeopathy.

3. Explain why many questions and assertions are outside the domain of scientific inquiry.

4. Discriminate between scientific and pseudoscientific explanations of natural phenomena.

SCIENTIFIC INQUIRY.

Many of us have learned that scientific inquiry proceeds by way of “The Scientific Method”, a method that allows the objective collection and interpretation of data. Thus was born the slogan that ‘Science is derived from facts’. A similar slogan that summarizes aspects of scientific inquiry states that ‘science is experiential and experimental’, indicating that the facts science deals with are experienced by the senses (vision, smell, hearing, touch and taste) and are derived from experiments. Other descriptions of science emphasized the ability to conclusively proof or falsify hypotheses as key characteristics of the scientific method.

“Scientific inquiry is not easily described apart from the context of particular investigations. There simply is no fixed set of steps that scientists always follow, no one path that leads them unerringly to scientific knowledge. There are, however, certain features of science that give it a distinctive character as a mode of inquiry. Although those features are especially characteristic of the work of professional scientists, everyone can exercise them in thinking scientifically about matters of interest in everyday life.”(1)

5. Recognize that there is no single scientific method; that the scientific enterprise consists of multiple methods and tools of investigation for evaluating ideas.

6. Understand that scientific inquiry is not formulaic in practice.

The goal of science is an understanding of the functioning of the universe. Such understanding is achieved by means of four components: (a) collection of evidence or observation of specific facts or phenomena (including those derived from experiments). Science deals only with the material world (i.e., it seeks a naturalistic explanation), and this is reflected in the old descriptor that the observations are made using our senses (or instrumental extensions of our senses), (b) formulation of generalizations about such phenomena, (c) production of causal hypotheses relating the phenomena (i.e., formulation of explanations, expressions of understanding of the phenomena). Such understandings are reached by logic and rational thinking. Finally, (d) the causal hypotheses are tested by means of further observations and experimentation. Two types of evidence are accepted by practicing scientists: (1) confirmation of hypothesis by data strengthens its validity, and (2) repeated inconsistency of data with a hypothesis eventually leads to the rejection of the hypothesis.

7. Articulate a central assumption of science: the universe is real and operates according to universally consistent rules, and we can discover these rules by logical thought subject to test through experiments and observations.

Application:

1) Mendel formulated a model for the mode of inheritance of traits in peas. He tested this model by crossing peas with particular traits and comparing the observed phenotypic ratio of the offspring with the same ratio predicted by the model.

2) By studying the work of Fred Griffith, Oswald Avery deduced that the ‘transforming factor’ of Griffith must be the genetic material. Therefore, by repeating Griffith’s transformation experiment with increasingly selective and purified material of the killed, encapsulated, virulent bacteria Avery could identify DNA as the genetic material.

3) Meselsohn and Stahl reasoned that whereas DNA replication could proceed by different mechanisms, the correct mechanism should be based on the structure of the DNA molecule (double helix of anti-parallel, complementary strands of nucleic acids) and must guarantee the unaltered transfer of genetic material to the daughter cells. The authors could distinguish between newly synthesized DNA and ‘old’ DNA by growing bacteria in media with or without heavy isotopes of nitrogen and measuring the distribution of DNA species of different mass. The different models predicted different distributions of ‘light’ and ‘heavy’ DNA. Because the observed distribution of ‘light’ and ‘heavy’ DNA matched the pattern predicted when DNA is replicated by a semi-conservative model and was distinct from the patterns predicted by the other models, the authors concluded that DNA replication proceeds by a semi-conservative model.

Science demands evidence:

Scientific statements are backed up by evidence. As we have seen the evidence are the results of experiments that either affirm or reject a hypothesis or answer a question. This is, the evidence are data collected by researchers.

“Sooner or later, the validity of scientific claims is settled by referring to observations of phenomena. Hence, scientists concentrate on getting accurate data. Such evidence is obtained by observations and measurements taken in situations that range from natural settings (such as a forest) to completely contrived ones (such as the laboratory). To make their observations, scientists use their own senses, instruments that enhance those senses (such as a microscope), and instruments that tap characteristics quite different from what humans can sense (such as magnetic fields). Scientists observe passively (earthquakes, bird migrations), make collections (rocks, shells, butterflies, flowers), and actively probe the world (e.g., as by boring into the earth’s crust, coring the trunk of a tree, or administering experimental medicines).”(1)

“In some circumstances, scientists can control conditions deliberately and precisely to obtain their evidence. They may, for example, control the temperature, change the concentration of chemicals, or choose which organisms mate with which others. By varying just one condition at a time, they can hope to identify its exclusive effects on what happens, uncomplicated by changes in other conditions. Often, however, control of conditions may be impractical (as in studying stars), or unethical (as in studying people), or likely to distort the natural phenomena (as in studying wild animals in captivity). In such cases, observations have to be made over a sufficiently wide range of naturally occurring conditions to infer what the influence of various factors might be. Because of this reliance on evidence, great value is placed on the development of better instruments and techniques of observation, and the findings of any one investigator or group are usually checked by others.”(1)

Thus, science is based on experimental data. These are obtained from natural experiments in which the researcher is largely a(n) (passive) observer or from controlled experiments performed mostly in laboratory settings in which conditions are highly controlled. Note that the initial observations of a research project could be observations made in nature as well as the results of a previous experiment (often published in the literature).

Science is a blend of logic and imagination:

“Although all sorts of imagination and thought may be used in coming up with hypotheses and theories, sooner or later scientific arguments must conform to the principles of logical reasoning – that is, to testing the validity of arguments by applying certain criteria of inference, demonstration, and common sense. Scientists may often disagree about the value of a particular piece of evidence, or about the appropriateness of particular assumptions that are made – and therefore disagree about what conclusions are justified. But they tend to agree about the principles of logical reasoning that connect evidence and assumptions with conclusions.”(1)

Application:

1) The different models by which DNA could replicate required a good understanding of the structure of DNA and of the biological consequences of the replication process. However, the models also reflect creative thinking by Meselsohn and Stahl. Similarly, the researchers’ used their imagination in finding experiments that could distinguish between these models. To predict the distribution of the ‘light’ and ‘heavy’ DNA produced by each model, in contrast, required logical reasoning. Similarly, the comparison of observed and predicted data is based on logic.

2) Similarly, the structure of DNA was deduced by Watson and Crick by knowing the facts (whatever the structure of DNA. The molecule contained equal amounts of phosphate, deoxyribose, and cyclic, nitrogen-containing bases of which the two purines were larger than the two pyrimidines, the relative abundance of the bases followed Chargaff’s rules, and Rosalind Franklin’s work had demonstrated the double, helical nature of the molecule) and a blend of creative and logical thinking.

3) A similar blend of imagination and logical thinking is evident in the design of the rII frameshift mutations of bacteriophage T4 and their usage in unraveling the triplet nature of the genetic code by Francis Crick and his co-workers.

“Scientists do not work only with data and well-developed theories. Often, they have only tentative hypotheses about the way things may be. Such hypotheses are widely used in science for choosing what data to pay attention to and what additional data to seek, and for guiding the interpretation of data. In fact, the process of formulating and testing hypothesis is one of the core activities of scientists. To be useful, a hypothesis that cannot in principle be put to the test of evidence may be interesting, but it is not likely to be scientifically useful.”(1)

Application:

1) Once Crick and co-workers realized that proflavin induced frameshift mutations in bacteriophage T4 by adding (or deleting) a single base the authors realized that these mutations could be used to establish the triplet nature of the genetic code. Next, the authors set up specific experiments, using the frameshift mutants, to verify that the genetic code was a triplet code.

8. Explain why a hypothesis must be falsifiable through experiments or observations to be considered scientific.

Application:

1) The different models of DNA replication considered by Meselsohn and Stahl are, in fact, different hypotheses for the distribution of ‘new’ and ‘old’ DNA in the daughter cells after replication. Note, that the DNA distribution predicted by each model could actually be detected if it occurred. That is, each model (or hypothesis) was falsifiable by the experiment. One might also have hypothesized that DNA is replicated by the activity of little angels with light-blue diapers having yellow pokey-dots. However, because we cannot visualize or demonstrate the presence of such angels, this hypothesis is un-falsifiable and, therefore, scientifically useless.

Note, that a hypothesis may not be falsifiable at one point but when suitable techniques are developed can be falsifiable later. Other, hypotheses (such as the blue angle one) are unlikely ever to become falsifiable.

Note, if the proposed mechanism of a phenomenon is very novel, unexpected, or unlikely the evidence to corroborate it shall be more extensive, stronger, and broader than that needed to confirm a more conventional explanation of the facts.

Application.

a) Thus, those that argue that chronic arthritis can be cured or slowed by wearing copper armbands must provide extensive and strong proof of this claim because this explanation does not currently fit with the theory or experimental evidence of modern medicine.

“The use of logic and the close examination of evidence are necessary but not usually sufficient for the advancement of science. Scientific concepts do not emerge automatically from data or from any amount of analysis alone. Inventing hypotheses or theories to imagine how the world works and then figuring out how they can be put to the test of reality is as creative as writing poetry, composing music, or designing skyscrapers. Sometimes, discoveries in science are made unexpectedly, even by accident. But knowledge and creative insight are usually required to recognize the meaning of the unexpected. Aspects of data that have been ignored by one scientist may lead to new discoveries by another.”(1)

9. Be able to explain how science works as a blend of logic, imagination, and serendipity to produce theories

Science explains and predicts:

“Scientists strive to make sense of observations of phenomena by constructing explanations for them that use, or are consistent with, currently accepted scientific principles. Such explanations – theories – may be either sweeping or restricted, but they must be logically sound and incorporate a significant body of scientifically valid observations. The credibility of scientific theories often comes from their ability to show relationships among phenomena that previously seemed unrelated. The theory of moving continents, for example, has grown in credibility as it has shown relationships among such diverse phenomena as earthquakes, volcanoes, the match between types of fossils on different continents, the shapes of continents, and the contours of the ocean floors.”(1)

The essence of science is validation by observation. But it is not enough for scientific theories to fit only the observations that are already known. Theories should also fit additional observations that were not used in formulating the theories in the first place, i.e., theories should have predictive power. Demonstrating the predictive power of a theory does not necessarily require the prediction of events in the future. The prediction may be about evidence from the past that has not yet been found or studied. A theory about the origins of human beings, for example, can be tested by new discoveries of human-like fossil remains. This approach is clearly necessary for the study of processes that usually occur very slowly, such as the building of mountains or aging of stars. Stars, for example, evolve more slowly than we can usually observe. Theories of evolution of stars, however, may predict unsuspected relationships between features of starlight that can then be sought in existing collections of data about stars.”(1)

10. Be able to explain how science produces theories that have both explanatory and predictive power subject to validation by experiments and observations.

Application:

1) Mendel’s laws allowed Mendel (and any one else) to predict the phenotypic ratio of traits in crosses.

2) The structure of DNA discovered by Watson and Crick immediately suggested (predicted) ways by which DNA replication most likely occurred.

Scientists try to identify and avoid bias:

“When faced with a claim that something is true, scientists respond by asking what evidence supports it. But scientific evidence can be biased in how the data are interpreted, in the recording or reporting of the data, or even in the choice of what data to consider in the first place. Scientists’ nationality, sex, ethnic origin, age, political convictions, and so on may incline them to look for or emphasize one or another kind of evidence or interpretation. For example, for many years the study of primates – by male scientists – focused on the competitive social behavior of males. Not until female scientists entered the field was the importance of female primates’ community-building behavior recognized.”(1)

“Bias attributable to the investigator, the sample, the method, or the instrument may not be completely avoidable in every instance, but scientists want to know the possible sources of bias and how bias is likely to influence evidence. Scientists want, and are expected, to be as alert to possible bias in their own work as in that of other scientists, although such objectivity is not always achieved. One safeguard against undetected bias in an area of study is to have many different investigators or groups of investigators working on it.”(1)

11. Demonstrate with examples that the scientific enterprise is embedded in and influenced by political, economic, and cultural contexts of the times.

Application:

1) Lysenko (1898-1976) was a Soviet biologist who had a disastrous effect upon Soviet biology for more than 20 years. He performed experiments by cold treating seeds to increase grain yields. He claimed that these benefits were inherited by future generations of the grain. This idea was an example of the long-discredited theory of Jean Baptiste Lamarck, called "inheritance of acquired characteristics." This is the idea that externally caused changes to an organism (like losing a finger) can affect future generations (by maybe causing a weak finger). By this theory, an antelope, stretching its neck to reach higher branches, had evolved into a giraffe. This sounds like a joke in light of Mendellian genetics and our current understanding of the DNA molecule. Many people found out that this was a cruel joke indeed. Lysenko's theory fit well with Stalin's ideas, and he was promoted to the post of director of the Institute of Genetics of the USSR Academy of Sciences. The previous director, the respected biologist N. I. Vavilov, was fired, and eventually arrested and exiled to Siberia. Other biologists kept quiet about genetics, or suffered similar fates. And Soviet biology (and farming techniques) re-entered the dark ages. Stalin's exiling and killing of the successful farmers (kulaks) did not help matters, and the USSR suffered droughts in years of abundant rainfall. It was not until after Khruschchev's fall from power in 1964 that Lysenko was finally ousted from power, and Soviet biology was allowed to re-enter the 20th century.

2) Administrators, policy-makers, and researchers have concluded that it would be very difficult to keep every hint of bias out of investigations of the effects of drugs on patients if the investigator’s research is funded by the pharmaceutical company producing the drug under investigation or the investigator has stock (and, thus, financial interest) in the company. Most academic and governmental agencies do not allow researchers to have financial interests in the company whose drugs they study. Similarly, many journals request that investigators state their financial interests in the drugs they study.

12. Identify potential sources of bias in science attributable to the investigator (e.g., cultural or ideological), the sample used, the method employed, or the instrumentation used with the goal of achieving objective results.

Science is not authoritarian:

“It is appropriate in science, as elsewhere, to turn to knowledgeable sources of information and opinion, usually people who specialize in relevant disciplines. But esteemed authorities have been wrong many times in the history of science. In the long run, no scientists, however famous or highly placed, is empowered to decide for other scientists what is true, for none are believed by other scientists to have special access to the truth. There are no pre-established conclusions that scientists must reach on the basis of their investigations.”(1)

“In the short run, new ideas that do not mesh well with mainstream ideas may encounter vigorous criticism, and scientists investigating such ideas may have difficulty obtaining support for their research. Indeed, challenges to new ideas are the legitimate business of science in building valid knowledge. Even the most prestigious scientists have occasionally refused to accept new theories despite there being enough accumulated evidence to convince others. In the long run, however, theories are judged by their results: when someone comes up with a new or improved version that explains more phenomena or answers more important questions than the previous version, the new one eventually takes its place.

Applications:

1) Although early work suggested that DNA rather than protein was the genetic material, the more complex three-dimensional structure of proteins of protein made it difficult for many biologists of the 1940s and 1950s to accept that DNA was the genetic material.

13. All science relies upon the acquisition of evidence obtained through experimentation and observation to test hypotheses and theories rather than upon the acceptance of ideas based on authority.

THE SCIENTIFIC ENTERPRISE.

“Science, as an enterprise, has individual, social, and institutional dimensions. Scientific activity is one of the main features of the contemporary world and, perhaps more than any other, distinguishes our times from earlier centuries.”(1) Science and technology characterize our lives. Most aspects of daily life are made simpler by technological applications (can you imagine a house without electricity, a TV, microwave oven, or a personal computer?). Evening newscasts report daily on scientific breakthroughs in the life sciences, physics, and astronomy. We realize that technology has/is changed(ing) the environment in which we live and pollution, greenhouse gases and global warming have become hotly debated household words and political rallying points. Similarly, every citizen needs to have an understanding of the cellular and molecular workings of the body to keep up with the progress in medicine reported daily. How can one be an active participant in debates on cloning, stem cell research, or genetically modified foods if one does not have the requisite scientific background?

14. Demonstrate with examples that science is a distinguishing feature of the contemporary world, and that the scientific enterprise is embedded in and influenced by political, economic, and cultural contexts of the times.

Science is a complex social activity:

“Scientific work involves many individuals doing many different kinds of work and goes on to some degree in all nations of the world. Men and woman of all ethnic and national backgrounds participate in science and its applications. These people – scientists and engineers, mathematicians, physicians, technicians, computer programmers, librarians, and others – may focus on scientific knowledge either for its own sake or for a particular practical purpose, and may be concerned with data gathering, theory building, instrument development, or communicating.”(1)

Scientists do not live in isolation from the rest of society. There life and thinking are influenced by their times, just as they are of any other individual of society. But this also means that a scientist’s scientific work and thinking is influenced by the time and society in which he/she works.

Application:

b) Before Mendel, biologists accepted that pangenesis explained how traits were inherited.

c) Mendelian genetics and evolution by natural selection provided a scientific impetus for the eugenics movement of the first half of the 20th century.

d) For the first 70 year of the 20th century, medicine was very much male-centered. Because women were largely kept out of the sciences and males were doing all the research. Drug testing was done largely on male volunteers.

“As a social activity, science inevitably reflects social values and viewpoints. The history of economic theory, for example, has paralleled the development of ideas of social justice – at one time, economists considered the optimum wage for workers to be no more than what would just barely allow workers to survive. Before the twentieth century, and well into it, women and people of color were essentially excluded from most of science by restrictions on their education and employment opportunities; the remarkable few who overcame those obstacles were even then likely to have their work belittled by the science establishment.”(1) (See also: Lysenko.)

Also the topics that are ‘in’ and the questions that should be studied by scientists are affected by the prevailing needs and fads of society. Up until the 1960s infectious diseases and their treatment with anti-microbials were major topics in medicine and biomedical research. President Nixon launched the ‘war-on’ cancer program at the end of the 1960’s and cancer has dominated medical research for the second half of the 20th century.

“The direction of scientific research is affected by informal influences within the culture of science itself, such as prevailing opinion on what questions are most interesting or what methods of investigation are most likely to be fruitful. Elaborate processes involving scientists themselves have been developed to decide which research proposals receive funding, and committees of scientists regularly review progress in various disciplines to recommend general priorities and funding.”(1) Research proposals are evaluated by committees of peers that judge the merits of a proposal against the prevailing understanding of the topic and the qualifications of both the institution where the research will be done as well as against the qualifications of the individual(s) who will do the research. This mechanism protects against wasting funds on reinventing the wheel or on half-baked ideas. However, such committees may (inadvertently?) set the direction of the science and make it more difficult to research unorthodox, innovative explanations.

“Science goes on in many different settings. Scientists are employed by universities, hospitals, businesses and industry, by government, independent research organizations, and scientific associations. They may work alone, in small groups, or as members of large research teams. Their places of work include classrooms, offices, laboratories, and the natural field settings from space to the bottom of the sea.”(1)

In the early days scientists would mostly work alone and would fund their own work. As research became more complex and scientists received funding from external agencies, ownership of research results and intellectual property rights have become equally complex issues. Thus, scientist that are paid by the government are governmental employees, and are representatives of the government (e.g., scientists can not travel to Cuba because the US government does not allow such travel). The university, institution, employer or government may be the owner of the research results when the work was funded by the university, the company you work for, or the government.

“Because of the social nature of science, the dissemination of scientific information is crucial to its progress. Some scientists present their findings and theories in papers that are delivered at meetings or published in scientific journals (See: lab 3 Scientific papers). Those papers enable scientists to inform others about their work, to expose their ideas to criticism by other scientists, and, of course, to stay abreast of scientific developments around the world. The advancement of information science (knowledge of the nature of information and its manipulation) and the development of information technologies (especially computer systems) affect all of science. Those technologies speed up data collection, compilation, and analysis; make new kinds of analysis practical; and shorten the time between discovery and application.”(1)

An important step in the publishing process of science papers is the peer-review process. Before a paper is accepted for publication by a scientific journal, the paper is reviewed by two or more external reviewers. The latter are researchers with up-to-date, and active knowledge of the research submitted, that is, they are peers. The peer-review process is a main guarantee for the scientific quality of the published paper. Is the thesis (explanation) suggested by the submitted paper plausible in light of our knowledge? Do the experiments provide good arguments that support the thesis? What arguments are necessary to back up the thesis? Are the experiments done appropriately? Are the experiments properly analyzed and do the authors draw the right conclusions?

Because the peer-review process provides a safe-guard to published papers, scientists consider published claims facts or observations (be it tentative facts until others and further experiments confirm them) that increase or modify our understanding of a phenomenon. It is important to distinguish between scientific claims that have been peer-reviewed and those that have not. Quite often, news media will report on scientific discoveries prior to the peer-review process. Such claims have not been peer-reviewed and, therefore, lack credibility.

15. Understand that it is the responsibility of scientists to communicate their findings to the scientific community and, ideally, to the public, and that many scientists participate in public affairs as both scientists and citizens.

Science is organized into content disciplines and is conducted in various institutions:

“Organizationally, science can be thought of as a collection of all of the different scientific fields, or content disciplines. From anthropology to zoology, there are dozens of such disciplines. They differ from one another in many ways, including history, phenomena studied, techniques and language used, and kinds of outcomes desired. With respect to purpose and philosophy, however, all are equally scientific and together make up the same scientific endeavor. The advantage of having disciplines is that they provide a conceptual structure for organizing research and research findings. The disadvantage is that their divisions do not necessarily match the way the world works, and they can make communication difficult. In any case, scientific disciplines do not have fixed borders. Physics shades into chemistry, astronomy, and geology, as does chemistry into biology and psychology, and so on. New scientific disciplines (astrophysics and sociobiology, for instance) are continually being formed at the boundaries of others. Some disciplines grow and break into sub disciplines, which then become disciplines in their own right.”(1)

“Fundamentally, the various scientific disciplines are alike in their reliance on evidence, the use of hypothesis and theories, the kinds of logic used, and much more. Nevertheless, they differ greatly from one another in what phenomena they investigate and in how they go about their work; in the reliance they place on historical data or on experimental findings and on qualitative or quantitative methods; in their recourse to fundamental principles; and in how much they draw on the findings of other sciences. Still, the exchange of techniques, information, and concepts goes on all the time among scientists, and there are common understandings among them about what constitutes an investigation that is scientifically valid.”(1)

16. Describe the organization of science into distinctive disciplines with different subject matter and research agendas, and be able to compare and contrast the questions and methods of at least two different scientific disciplines through active study in those disciplines.

“Universities, industry, and government are also part of the structure of the scientific endeavor. University research usually emphasizes knowledge for its own sake, although much of it is also directed toward practical problems. Universities, of course, are also particularly committed to educating successive generations of scientists, mathematicians, and engineers. Industries and business usually emphasize research directed to practical ends, but many also sponsor research that has no immediate obvious applications, partly on the premise that it will be applied fruitfully in the long run. The federal government funds much of the research in universities and in industry but also supports and conducts research in its many national laboratories and research centers. Private foundations, public-interest groups, and state governments also support research.”(1)

“Funding agencies influence the direction of science by virtue of the decisions they make on which research to support. Other deliberate controls on science result from federal (and sometimes local) government regulations on research practices that are deemed to be dangerous and on the treatment of the human and animal subjects used in experiments.”(1)

There are generally accepted ethical principles in the conduct of science:

“Most scientists conduct themselves according to the ethical norms of science. The strongly held traditions of accurate record keeping, openness, and replication, buttressed by the critical review of one’s work by peers, serve to keep the vast majority of scientists well within the bounds of ethical professional behavior. Sometimes, however, the pressure to get credit for being the first to publish an idea or observation leads some scientists to withhold information or even to falsify their findings. Such a violation of the very nature of science impedes science. When discovered, it is strongly condemned by the scientific community and the agencies that fund research.” (1)

“Another domain of scientific ethics relates to possible harm that could result from scientific experiments. One aspect is the treatment of live experimental subjects. Modern scientific ethics require that due regard must be given to the health, comfort, and well-being of animal subjects. Moreover, research involving human subjects may be conducted only with the informed consent of the subjects, even if this constraint limits some kinds of potentially important research or influences the results. Informed consent entails full disclosure of the risks and intended benefits of the research and the right to refuse to participate. In addition, scientists must not knowingly subject coworkers, students, the neighborhood, or the community to health or property risks without their knowledge and consent.” (1)

“The ethics of science also relates to the possible harmful effects of applying the results of research. The long-term effects of science may be unpredictable, but some idea of what applications are expected from scientific work can be ascertained by knowing who is interested in funding it. If, for example, the Department of Defense offers contracts for working on a line of theoretical mathematics, mathematicians may infer that it has application to new military technology and therefore would likely be subject to secrecy measures. Military or industrial secrecy is acceptable to some scientists but not to others. Whether a scientist chooses to work on research of great potential risk to humanity, such as nuclear weapons or germ warfare, is considered by many scientists to be a matter of personal ethics not one of professional ethics.” (1)

Application:

a) Crops can be modified to be resistant to certain pests or herbicides. What are the ethical questions scientists should be asked?

b) To fight human diseases such as malaria or west nile disease (or plagues of crops or animals), insect vectors can be genetically modified to interrupt transmission of a disease-causing microorganism. E.g., mosquitoes can be made that no longer can transmit the malaria parasite or the west nile virus. What ethical quations should scientists be asked?

c) Stem cells may be used to stop and reverse the deleterious effects of chronic diseases. Omnipotent stem cells can be obtained from feta. However, before therapeutic applications can be established a large amount of stem cell research must be done. What ethical questions should scientists be asked?

d) It is possible that organs/tissues can be regenerated in situ by stem cell research or be grown in vitro and implanted (cloning). Thus an embryo formed by replacing the nucleus of a zygote with the nucleus of one’s epidermal cell, can be grown into pancreas tissue in vitro. Because this pancreas tissue has the same genome as have all cells of your body, it can be transplanted without fear of tissue rejection. Again, what questions should scientists be asked.

Scientists participate in public affairs both as specialists and as citizens:

“Scientists can bring information, insight and analytical skills to bear on matters of public concern. Often they can help the public and its representatives to understand the likely causes of events (such as natural and technological disasters) and to estimate the possible effects of projected policies (such as ecological effects of various farming methods). Often, they can testify to what is not possible. In playing this advisory role, scientists are expected to be especially careful in trying to distinguish fact from interpretation, and research findings from speculation and opinion; that is, they are expected to make full use of the principles of scientific inquiry.” (1)

“Even so, scientists can seldom bring definitive answers to matters of public debate. Some issues are too complex to fit within the current scope of science, or there may be little reliable information available, or the values involved may lie outside of science. Moreover, although there may be at any one time a broad consensus on the bulk of scientific knowledge, the agreement does not extend to all scientific issues, let alone to all science-related social issues. And of course, on issues outside of their expertise, the opinions of scientists should enjoy no special credibility.” (1)

“In their work, scientists go to great lengths to avoid bias – their own as well as that of others. But in matters of public interest, scientists, like other people, can be expected to be biased where their own personal, corporate, institutional, or community interests are at stake. For example, because of their commitment to science, many scientists may understandably be less than objective in their beliefs on how science is to be funded in comparison to other social needs.” (1)

17. Understand that scientist have a generally accepted set of ethical principles for the conduct of science.

REFERENCES:

1) Project 2061 of American Association for the Advancement of Science, Science for all Americans (1990). Oxford University Press, New York, NY.

2)

3) wysiwyg://12//

4) Mayr Ernst. This is biology: the science of the living world (1997).

5) Lederman Leon, The pleasure of learning, (2004). Nature (August 5) volume 430 p617.

Process of Science (See: laboratories).

18. Read scientific works written for an informed public and know how to find additional information that may be needed to fully understand the content of those works.

19. Conduct a scientific investigations, including the formulation of questions and hypotheses, the development of methods of investigation, the collection and analysis of data, and the presentation of the work in written and oral scientific style.

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