Title Page: The Philosophy and History of Science
University of the Western Cape
Botany Honours: 1999
Guest Lecturer: Dr Karen Joan Esler
(021) 808 3063
Contents:
- The Philosophy and History of Science
- Falsification in practice
Theories are generally not rejected simply because they have anomalies nor are they generally accepted simply because they are empirically confirmed.Larry Laudan
For the truth of the conclusions of science, observation is the supreme court of appeal. Sir Arthur Eddington
Science is divided into two categories, physics and stamp-collecting. Lord Rutherford
The early scientists
From historical records it appears that Aristotle (384-322 BC) was the first to construct a conceptual framework which we would describe as the science we call Biology. (The word “science” comes from the latin scire, to know, or scio, I know, while “biology” is derived from the Greek, bios, life). Aristotle’s Historia Animalium is a text on general zoology in which he set down all he knew about the animals of the world. Theophrastus (371-287 BC), a contemporary of Aristotle, did for botany what Aristotle did for zoology. However, after these men, and a handful of others, (notably, the philosopher Plato, 428-347 BC), there was little development for many centuries. The Church became the keeper of knowledge and dogma took the place of enquiry. Not that the darkness was complete. Points of light included the likes of Cardinal Nicolas of Cusa, 1401-1464, and Leonardo da Vinci, 1452-1519. The former was sympathetic to science and encouraged the study of mathematics, while the latter eloquently denounced those who preferred to study authorities rather than nature itself.
Figure 1 A time line, showing the years in which selected persons were alive.
Moore (1993) gives the birth year of the Scientific Revolution as 1543, the year Copernicus died. At this time, (European) human beliefs were under the rigid control of the church. Men like Bacon, Hume and Popper developed the philosophy of science. In 1687, Newton published his major contribution to physics, but his theories were to be made more general by Einstein some 250 years later. Einstein’s work was to have considerable influence on a young Karl Popper. Amongst musical composers, Newton could have been Beethoven, or Brahms, both of whom were known to Einstein (he played violin). Jan van Riebeeck was in the Cape from 1652 to 1662, establishing a way station to the East and the country known as South Africa today. Shaka and Beethoven were contemporaries (but how different their worlds were!) and Jan Smuts (soldier, statesman, philosopher, botanist) lived through the Anglo-Boer wars (1880-1881 and 1899-1902) as well as both World Wars (1914-1918 and 1939-1945).
Moore, in his book, Science as a Way of Knowing, pinpoints 1543 as the birth year of the re-awakening known as the Scientific Revolution, listing three reasons. Firstly, the recovered and translated works of Archimedes (287-212 BC) were published. Secondly, Copernicus (1473-1543) published his theory that the earth revolves around the sun (and not the other way around, as the dogma of the day declared). Thirdly, Vesalius (1514-1564) published his book, based on dissections, on the anatomy of the human body. Vesalius’ account replaced that of Galen who was born around 129 AD and died around200 AD. We are again reminded of relative inactivity that lasted some 17 centuries.
Names like Tycho Brahe (astronomy, 1546-1601), Galileo Galilei (physics and astronomy, 1564-1642), Johannes Kepler (astronomy, 1571-1630), William Harvey (physician, 1578-1657) and René Descartes (philosophy and mathematics, 1596-1650) are found in the record of the Scientific Revolution. To illustrate the contributions made by these people, Descartes, sometimes called the founder of modern philosophy, wrote the famous phrase “cogito ergo sum” – “I think, therefore I am” and we remember him every time we refer to “Cartesian co-ordinates”. However, the name we must emphasize in connection with the philosophy of science is that of Sir Francis Bacon (philosopher, 1561-1626).
The awakening of experimentation – induction and deduction
Prior to Bacon, people’s thoughts were guided largely by myth and legends of the day. Superstition and supernatural played important roles. Instead of accepting the word of the authorities of the day, Bacon emphasized that it was better to accumulate knowledge by experiencing the natural world. Up until then, the method was to start an enquiry with a point of view dictated by the Church and then to derive the consequences. For example, the teaching of the Church that man was god’s special creation, all else being put there for the benefit of man, lead to the dogma that the Earth was the centre of the Universe. The observation that the stars and planets moved lead to the conclusion that these rotated about the earth. There are (beautifully crafted) models in museums in Europe which depict this representation of reality. Earth is shown in the middle of the model, with the sun, moon, planets and stars on hoops, encircling the earth. Copernicus published his contrary ideas in 1543, dying shortly after this. Bacon, 50 years later, emphasized the importance of experimentation, the gaining of knowledge about reality by experiencing reality. (It is interesting that the French word “expériences” means “experiment” – to refer to an experience one must use the word “éprouver”. This is probably because the word used by medieval writers, “esperienza” was sometimes used with the meaning “experience”, sometimes “experiment”.
Bacon wanted scientists to begin their studies with data not faith. Collecting data by observation or experiment, the scientist would then be able to formulate an explanation for the workings of the world around them. Today we use the word “induction” to describe a process whereby one argues from the particular (the facts that one has gathered) to the general (the theories one formulates). Bacon was arguing against the form of deductive reasoning that was current in his day. He did not want scientists to begin with statements based on faith (religion) and to deduce the nature of reality from this. Instead he wanted scientist to begin with their experiences in the real world and to build knowledge on these (he wanted scientists to practice induction). This does not mean that deduction, as a method of reaching conclusions, is invalid. Deduction (arguing form the general to the particular) is an important tool used by all modern scientists.
As an example of deduction, a popular misrepresentation of the facts is to be found in cartoons that depict a cave man, a wooden club on his shoulder, dragging a cave woman by the hair while a dinosaur raises its long neck in the background. If (scientists might say to themselves) man evolved from small, furry pre-mammals which scurried around in the undergrowth at the time when the likes of Tyrannosaurus rex lived and died, then we would not expect to find fossils of man in the same rocks containing fossils of dinosaurs. The fact that no rocks have ever been discovered containing fossils of man and dinosaurs is one of the pieces of evidence which allows us (induction) to formulate the hypothesis that man and dinosaurs did not co-exist. Thus, both induction and deduction are thought process used by modern scientists.
All the scientists of his day and for the next three centuries accepted Bacon’s emphasis of induction as a means of learning about the real world. This period is characterized by an explosion in the amount of knowledge gathered by scientists and by the development of the tools that allowed scientists to gather this knowledge. Perhaps the most important of these tools was the microscope, developed to a high degree by Anton von Leeuwenhoek (1632-1723), and used by him to describe micro-organisms. (Recall that Bacon dies in 1626). Robert Hooke (1635-1701), who developed the compound microscope (two lenses, one at either end of the tube, compared to von Leeuwenhoek’s single-lens instrument), studied the finer detail of animals and plants. Hooke was the first to describe cells, but it would be another 200 years before the nature and role of cells would be understood.
Hypothesis, Theory and Law
Sir Isaac Newton (1642-1727) may have been the first scientist to use the word “hypothesis” as we use it today. (It is difficult to be precise because the word had a somewhat different meaning up until about this time. Therefore, when one finds him being critical about hypotheses, saying that they had no place in scientific investigation, one must first ask what he meant by the word “hypothesis”). Reading between the lines, it seems that he thought of a hypothesis as an explanation for observations made and that such hypotheses would be the basis for experiments that would produce further information. Today, we might define this term in the following way: A hypothesis is a tentative conjecture, proposition or supposition encapsulating the best available knowledge about some phenomenon. Clearly, Newton was thinking in Baconian terms in which knowledge is accumulated by observation (experimentation).
Davis Hume (1711-1776) was a Scottish philosopher who, like Bacon, maintained that knowledge came from observation and experience (rather than from church-supported dogmas). However, contrary to Bacon, Hume was highly critical of induction as a method. Hume’s attack on induction was part of a wider criticism of causal inference (that some event could be inferred to be the cause of another). In regard to induction, Hume pointed out observing that a certain pattern of events lead to a concluding event on a couple of occasions could under no circumstance be taken to justify a belief in a particular pattern would always lead to the concluding event.
Although Hume is considered the first to be critical of induction, it remained the approach taken by scientist for some two centuries following. For example, Darwin (1809-1822) wrote that he used the “true Baconian method”. Ralph W. Lewis, a professor of the department of Natural Sciences at MichiganStateUniversity, records (in a paper published in 1988) that in the early 1930’s, when he started to study biology, textbooks and teachers taught the Baconian method as the method of science. This he describes with the words: “gather all the facts, classify them and then somehow, if you have gathered the right facts, they will crystallize into a theory”.
Note Lewis’ use of the word “theory” as a synonym for “hypothesis”. In our opinion, use of this word should be restricted to cases where a hypothesis could no longer be described as being a tentative proposition. We think of a theory as a hypothesis for which there is some considerable degree of acceptance amongst the majority of scientists, without elevating it to the next level, that of “fact”, “truth” or “law”. Atabout the time of Lewis was a student, being taught the Baconian method, Popper was writing a book that would revolutionise scientist’s view of the scientific method.
The modern approach to science: Falsification
According to Sir Karl popper (1902-1994), the crucial distinction between science and non-science relates to the presence or absence of falsifiability. If a line of thought has implications that could be used to test the validity of that line of thought, if it could be falsified, then that line of thought could be described as scientific. On the other hand, if a line of thought produced no means of testing the ideas contained, then that line of thoughtcould not be described as scientific. (An obvious example would be to compare astrology to astronomy.) This basic idea, that of falsification, stating that the ability to falsify demarcates science from non-science, was published by Popper in 1934, in the book titled Logik der Forshung. He translated this book into English (expanding it at the same time) and published it as The Logic of Scientific Discovery in 1959.
Popper began where Hume left off. No matter how many times (he wrote) we see a swan and observed it to be white, we can never logically derive the universal statement “all swans are white”. However, he then went on to point at a logical asymmetry between verification on the on ehand and falsification on the other. He pointed out that one need record only one instance of a black swan to be logically entitled to derive the statement “not all swans are white”. Popper suggested that scientists are never involved in verification (induction); they are always involved in falsification.
Some authors credit Popper with the invention of the “hypothetico-deductive method” but others traced this method back to Newton while others traced it all the way back to Plato. According to this description of how scientists practice their profession, a scientists starts by formulating a hypothesis to describe the workings of some phenomenon. Statements that make predictions about consequences that would allow if the hypothesis were valid are then deduced from the hypothesis. The scientist then exposes him or herself to the conditions of the prediction (for example, an experiment is conducted), and the results are examined to see whether the predicted outcomes occurred. If they did not, then the hypothesis is an adequate description of the phenomenon; falsification has occurred. However, if observations are as predicted then the scientist does notconclude that the hypothesis is true. Instead a properly trained scientist will try to think of some other experiment with which to test the hypothesis.
As we have indicated, we do not agree that Popper invented the hypothetico-deductive method. In our opinion, Popper did no more than write down clearly what was in the minds and practice of the foremost scientists of his day. For example, the first edition of Sir Ronald Fisher’s book Statistical Methods for Research Workers (he was born in 1890 and died in 1962) appeared in 1925. This book sets out many of the basic ideas used today by scientists in the statistical processing of hypotheses. Neyman and Pearson published such a framework in a series of papers appearing between 1928 and 1936. Recall that Popper’s Logik der Forshung was published in 1934.
The first reaction to Popper’s concept of falsification is that the distinction between scientists and non-scientists is that the first are forever trying to falsify their theories. Popper wnet so far as to be prescriptive, suggesting that one should distinguish a scientist from a non-scientist on this basis. An examination of the historical record indicates however that this notion is false. In 1962 Thomas Kuhn (1922-1996) publisked his book The Structure of Scientific Revolutions. In this book he suggested that scientists have, at any one time, a core of information which they do not question (make no attempt to falsify) and that they spend their time working in the periphery around tis core, colouring in the details, as it were. In this phase, Kuhn describes them as practicing normal science and he refers to the basic core as the paradigm. In simplistic terms, scientists practicing normal science are people looking for puzzles to solve. The tools with which these puzzles are solved are supplied by the paradigm, the basic, unquestioned core. The anomalies these scientists might encounter while solving such a puzzle will be noted but the will not necessarily be taken to be critical of the paradigm to such an extent that it should be discarded. However, when enough of these anomalies have accumulated that they can no longer be ignored, a revolution may occur an the paradigm of the day can be replaced by another paradigm, Like all revolutions, this can be a very painful time, with much controversy. However, if the paradigm is accepted an an improvement on the old, then this new paradigm is taken up as the unquestioned core of a new normal science and scientists return to the fleshing out the detail around this core.
Kuhn’s view of science is very attractive because it is such a strikingly accurate description to be found in the historical record of the progress of knowledge. Later in his life, Popper had to concede that his concept of demarcation based on falsifiability was insufficient, that reality is more complicated than this. However, we are of the opinion that Popper’s suggestion that modern scientist should spend their day trying to falsify what they consider to be the truth should not be discarded. According to Kuhn most scientist are practicing normal science most of the time, but, we belive, a healthy dose of self-criticism is always valuable. Popper wanted scientists to formulate their theories unambiguously as possible, so as to expose these theories as far as possible to the possibility of falsification.
We hope that the brief description we’ve given of the history and philosophy of science will help you to walk a middle road between Popper and Kuhn. One day, when you’ve constructed a fine piece of theory, keep in mind that the very best service you could do for your hypothesis (and yourself) would be to think of a strong test which could be used to falsify your hypothesis. The body of knowledge we refer to as science should never be thought as a series of true statements; instead think of science as a collection of statements, none of which has yet been falsified.
References
Blake RM, Ducasse CJ and Madden 1960. Theories of Scientific Method: The Renaissance through the Nineteenth Century. University of Washington Press, Seattle. 346pp.