Intro To Philosophy Of Science

Chem 105 Philosophy of Science Before getting into this discussion comes a disclaimer: Science, and this talk, deal strictly with the material. By definition the “supernatural” lies beyond the confines of science and the definitions of “universe” and “cosmos” used here. Please do not read anything more into this talk than that. Absolutely no offense of anyone’s beliefs is meant. Let me know, either in class or privately, if I had any foot-in-mouth disease. Although chemistry normally causes no concerns, some individuals have beliefs quite different from the accepted paradigms in other sciences. I will be using some examples from other sciences, especially physics, astronomy, and geology. Because the central paradigm of biology is controversial, I will neither discuss evolution nor answer questions about it. My purpose here is to explain how science works, not get into an argument about the relative merits of a particular theory. "Scientific Method" as taught in school: 1. Hypothesis is made 2. Experiments are performed to test the hypothesis. 3. Hypothesis is modified and step 2 is repeated. This is also known as the idea that science "makes predictions". A. INCONCLUSIVE EVIDENCE Many theories, even mathematical proofs, have occasionally been shown to be wrong. e.g. Euclid's fifth postulate of geometry. This was shown to be incorrect only in the 19th century, and gave rise to nonEuclidian geometry. Our senses must be the final arbitrators as to what constitutes reality. If one's senses are wrong, what can be believed? (Aristotle argued that only logic could be believed, not our senses.) Magicians, optical illusions, and various forms of mental illness conspire to show that senses can be confounded and confused. How can this be reconciled? Frankly, complete certainty is an unobtainable ideal. Theories must have sufficient evidence for its support, but they are not absolutely proven true by the evidence. In other words: Fallibility is a hallmark of science. Science uses a logic which is neither deductive nor inductive. The best way to explain how it works is by an example: a. The street gets wet when it rains. b. The street was wet this morning. c. Therefore it rained. Notice this falls outside the classical forms of reasoning. Unlike pure deductive or inductive reasoning, the conclusion (c) does not have to be true, even if the first two statements are true. There are other possible reasons for the wet street, including things like a pack of passing dogs. Science provides an explanation, but is held hostage to future developments. The history of science provides quite a few road kills. A spattering of examples: a. The 19th century idea that heat is a "subtle fluid". b. Water molecules consist of one hydrogen and one oxygen atom. Really! c. Protein was thought to be the genetic material. d. Continents do not move. e. Newtonian mechanics. At the time that these theories were ascendent, there was a reasonable amount of evidence to think they were correct. Later developments showed the theories wrong, but it did not show the scientists to be unjustified in creating the theory or thinking them correct. The ultimate goal of science is to discover the underling principles of the universe. This ambitious goal is to literally explain the entire cosmos, even where we cannot see in space or time. This is an

unusual concept, considering the incredibly limited region of space to which we have access. Even on the Earth, our senses limit our ability to see things that are too small. For example it was not accepted that bacteria existed and could cause disease until the 19th century. We are also limited in that it is not possible to travel either forward or backward in time. No one has shown an ability to construct the universe from a set of inherently true postulates. We must construct the laws governing the universe collectively, using a method which is self-correcting. There have been too many examples of blind alleys. What is remarkable is that science allows for change, even at the most fundamental levels. How does this self-correcting mechanism work? Lets look at an example. In the 1880's a very influential book on geology was written. It had been noticed that the continents seemed to fit together like a giant puzzle. There were also remarkable similarities in the geology of the regions of the “fitted” continents. Even the plants and animals, both living and fossilized, had eerie similarities. This book theorized that land bridges had once existed, which later sank. This would allow a transfer of the plants and animals, and the geology could be similar if the land bridge had been formed from a single geologic process. In 1912, Alfred Wegener suggested that a simpler explanation would be for the continents to actually have been a single continent at some time in the past. Although rejected by most geologists at the time, this theory was actually presented as a possible, but unlikely, alternative for several decades. The chief objection was the lack of a reasonable mechanism for humongous blocks of solid rock, the continents, to move around. The modern paradigm of plate tectonics came into acceptance in the 1960s’, principally due to the publication of accurate maps of the bottoms of the worlds oceans. Geologists attempt to state something which is true throughout time and describes the behavior of objects we can't even see. The poor geologists evidence is very restricted. Notice that this appears to follow the way science works as described in most books. There is more here than meets the eye. How would someone know that these geologic processes apply absolutely anywhere in space and time? This is difficult and the answer depends on what is being tested. In general, scientists determine some small set of observations as being critical. This means even the “best” theories rest on indirect arguments from observational evidence. Sciences like geology and astronomy are usually called “historical”, because we cannot go back to the beginning of the earth and modify its original composition to see what happens. We also do not have any laboratories that allow us to create stars or galaxies and watch their progress. Highly supported theories can give quick insight. e.g. Tunneling Scanning Microscope (This device won the inventors the Nobel Prize in physics) But are we really seeing atoms? Biochemists describe the large molecules they “see”, without mentioning the mountain of theory on which this “seeing” rests. Even subtle changes in these theories could cause a serious change in what the biochemist “sees”. So where is this going? Are we to take a jaded, cynical view then about science with arbitrary rules, dogma, and faith? No, of course not. Once again, scientific theories rest on good to excellent evidence which is not conclusive. This is why the paradigm of a science is called a theory (model). However the reverse is not true. All theories are revisable, but not all theories are equal. Let’s move a little deeper and get towards the real nature of science. The discussion so far can also apply to things which are not scientific. What about the concept that a good scientific theory makes successful predictions? B. PREDICTIVE SUCCESS A new scientific theory might make startling predictions that run out to be true (e.g. NMR). Actually predictive success is not an accurate description of science. One concept of a theory is that it is a collection of statements (often mathematical). These are generalizations about various things (atoms, gravity, quantum mechanics). These statements are applied to specific examples which can be measured. These experimental results are called observational consequences. Theories are bolstered when true, and damaged when false (deductive inference.) Therefore, if a theory makes a false prediction, something is wrong with the theory. That is, one or more statements of the theory are false. Saying a theory is falsifiable does not mean it is false. A person could die by being struck by a falling meteor. It does not mean you will die this way. A theory with no

observables is not scientific. C. NAIVE FALSIFICATION The arguements about science to this point are still seriously flawed. This was necessary since this picture of science is still widely taught. It seems pretty good, so what’s wrong? Either almost everything is “scientific” or almost all science is not science. Specifically, nearly all theories as presented in textbooks are unfalsifiable. E.g. Newtons laws might “temporarily” be overpoweved if that apple didn’t fall from the tree when disconnected. This logic could be applied to any theory. Newtonian theory can be made falsifiable by stating that the fundamental statements of the theory have numerous supplementary assumptions. E.g. Certain special systems exist in which gravity is the only force. This now makes almost anything science. e.g. “Benevolent beings from the Pleiades guide life on Earth” - Unfalsifiable, but any ad hoc supplementary assumptions could be added. This shows that the naive falsification criteria does not work. We can now get to the point” What is science? Science has three outstanding characteristics: I. Use of auxiliary hypothesis- An alteration or addition to a theory and independently testable. Theories are tested only in bundles. Individual theories are unfalsifiable and cannot confront the evidence by themselves. Theories are tested by bundling with unrelated theories. e.g. Newton’s law of gravity vs. Uranus II. UnificationA successful theory uses the same pattern of reasoning or problem-solving strategy for all cases. Newtonian mechanics explained the motion of projectiles, tidal cycles, pendulum oscillations, and motions of the planets with the same reasoning and small set of equations. III. Fecundity- Fertility A successful theory asks more questions than there are answers and leads towards the development of other sciences. Once again, Newton advertised his theory as a problem-solving method in a number of recalcitrant experiments. His methods were applied to heat, light, biology, earth sciences, and a host of other areas. Some worked and some didn’t, but several new disciplines came into existence because of the wide application of Newtonian mechanics.