Having considered so far (a) a definition of knowledge, (b) some of the foundations of knowledge -- perception, memory and language -- and (c) logic, by means of which we are able to deduce new propositions from what is already known, we shall now look at the first system of knowledge, that of the natural sciences.
There is a widespread, though usually unspoken, belief that science is a source of reliable, objective knowledge about reality, or even the only such source; and that scientific knowledge is certain and has been 'proved' in some sense. In this section we shall critically examine this belief. A good starting point may be to think of science as a human or social activity with certain rules, so that someone who is not following the rules is just not doing science -- just as someone who is not following the rules of chess is not playing chess. In these terms, then, we will try to investigate the rules that science follows.
Note that we will not be trying to tell scientists what they should be doing, but to understand more clearly how scientific knowledge has been arrived at, through the daily work of scientists, and how it is justified. This is not the same, however, as simply adopting the view which scientists themselves have of science -- and we will have to be similarly critical in other areas: a great artist is not necessarily the best person to explain to us on what grounds we call something a great work of art.
1. What Do Scientists Do? and: How has Science Got Here?
For each of the following areas decide whether it constitutes a natural science, and try to give reasons for your answers.
|a. ||astronomy ||b. ||biology ||c. ||chemistry |
|d. ||economics ||e. ||engineering||f. ||geography |
|g. ||geology ||h. ||history ||i. ||mathematics |
|j. ||philosophy ||k. ||physics ||l. ||psychology |
On the basis of the two lectures
you had, try to complete the following statements, (and thus obtain a summary of the lectures.)
- Modern science endeavours to give explanations of particular phenomena in terms of ________________ , which are universal propositions of the form "________________________________".
- There are two main ways of reasoning in science: _________________, which argues from particular observations to general hypotheses and therefore cannot guarantee that a conclusion is true even if the premisses are; and _________________, which is required to derive from the general laws _________________ which can be tested.
- Universal propositions are not capable of being proved conclusively, they can only be _________________; according to Karl Popper, the domain of science is limited to propositions which are ________________.
- Thus all scientific knowledge is only _________________: it is always subject to _________________ after further _________________ and may have to be rejected.
- Science is _________________ in that it is derived from and relates to experiment and observation. While scientists are often thought to be unimaginative, their work actually requires _________________. But science is capable of giving _________________ knowledge despite the subjective aspects of the work of individual scientists because of the requirement of _________________.
- Whereas scientific knowledge is often thought to accumulate gradually, Thomas Kuhn argues that instead it progresses through a series of _________________ alternating with periods of _________________.
- Whereas most of the time scientists in a field are working within a fixed _________________, which determines even what kinds of questions can be asked and what makes a theory 'good', during a ________________ the field almost reverts to the state of a _________________, (e.g. alchemy, creationism): each practitioner starts on his own and theories may be selected on the basis of extraneous considerations.
To understand a concept properly it often helps to demarcate or distinguish it from its opposite, (and from similar ones.) Give examples of the following:
- other forms of explanations than in terms of general laws;
- propositions which can be proved conclusively;
- knowledge that we are quite certain of but that is not empirical;
- knowledge that is subjective rather than objective;
- areas in which our knowledge has grown gradually over time.
For each of the following propositions decide whether it is verifiable, or only falsifiable, or neither.
- Time travel is an impossibility.
- There are many universes other than the one we happen to know about.
- The nearest star to the sun is Alpha Centauri.
- The laws of physics are the same throughout the universe.
- There is organic life on Mars.
We are here considering (propositional) knowledge as '(appropriately) justified true belief.'
In these terms we can now say that the truth of science is rather limited: it is the provisional truth of having stood up to experience so far -- about scientific knowledge we can say that 'it works.'
But not all true beliefs constitute knowledge: the justification of scientific knowledge consists in its having been arrived at by a certain process in which we, (or scientists for us,) are engaged.
Summary: The Hypothetico-Deductive Method of Science
Present scientific knowledge consists of all the hypotheses that have successfully stood up to testing -- so far. A scientific truth can therefore never be proved but will always be only provisional.
The objectivity of scientific knowledge, despite the subjectivity of the contributions of individual scientists, is due to the requirement that it must be universally testable.
2. Case Study: Darwin's Theory of Evolution
Since we are here going to consider the theory of evolution not from the point of view of modern biology but as an historical example of how a scientific theory developed, we need to think of it in the context of its time.
By now, Darwin's theory of evolution has of course found widespread acceptance, and for most people -- certainly in Western countries -- it is in some form part of their understanding of the world we live in.
Based on your general knowledge, try to explain the theory in your own words, in just a few sentences.
At the time when Charles Darwin was born, in 1809, both education and the academic world were very different from what they are today. Thus, at the boarding school he attended, from 1818 to 1825, the emphasis was completely on the classics: the languages, history and literature of ancient Greece and Rome.
Having started studying medicine for two years, he changed to theology, at Cambridge, to become a clergyman in the Church of England. However, by the time he completed his degree, in 1831, he had become more interested in scientific studies, especially biology and geology, largely perhaps through the influence of a young professor of geology, Adam Sedgwick (1785 -1873,) who was one of the first of a new kind of scientists: the sciences had not played an important role at the universities until about that time.
It was Sedgwick who recommended Darwin to travel on the H.M.S. Beagle as she set sail in December 1831 on a 6-year 'round-the-world map-making survey. The observations he made in the course of that voyage, especially in South America and the Galapagos Islands, together with what he had learnt about animal breeding as a young man with an interest in hunting and ideas he later met in An Essay on the Principle of Population, 1798, by the economist Thomas Malthus (1766 -1834,) formed the basis on which he formulated his theory of evolution in the years after his return.
By 1844 Darwin had completed what he called "a sketch of my species theory," but he chose not to have it published, apparently because he was worried about the reaction of the Church. So it was only in 1858, when he found the same ideas put forward in a paper by the naturalist A. R. Wallace (1823 -1913,) that Darwin published On the Origin of Species; and in The Descent of Man, 1871, he applied the theory of evolution to mankind. Charles Darwin died in 1882.
According to Karl Popper, "what characterizes the empirical method is its manner of exposing to falsification, in every conceivable way, the system to be tested" and this is the "criterion of demarcation" which distinguishes science from other human activities, and especially "from metaphysical speculation" (The Logic of Scientific Discovery, 1959, chapter I.)
What are the propositions put forward in the following passage from the "Introduction" of On the Origin of Species
? Which ones are based on inductive, which ones on deductive reasoning? What auxiliary hypotheses are employed, if any?
As many more individuals of each species are born than can possibly survive; and as, consequently, there is a frequently recurring struggle for existence, it follows that any being, if it vary however slightly in any manner profitable to itself, under the complex and sometimes varying conditions of life, will have a better chance of surviving and thus be naturally selected. From the strong principle of inheritance, any selected variety will tend to propagate its new and modified form.
The philosopher Antony Flew agrees that "falsifiability is an essential requirement in any truly scientific theory," and Sir Herman Bondi went so far as to declare that "there is no more to science than its method, and there is no more to its method than Popper has said."
Testing a scientific hypothesis like Darwin's theory of evolution means making predictions which can be checked against the outcomes of experiments or other observations. The predictions are deduced from the hypothesis to be tested together with certain auxiliary hypotheses.
Is Darwin's theory of evolution in principle falsifiable?
- What do you think Popper meant when in 1974 he described Darwin's theory as a "metaphysical research programme" ?
- According to the following passage from On the Origin of Species, how might Darwin's theory of evolution be falsified?
we already see how it [the theory of evolution] entails extinction; and how largely extinction has acted in the world's history, geology plainly declares. Natural selection, also, leads to divergence of character; for more living beings can be supported on the same area the more they diverge in structure, habits and constitution, of which we see proof by looking at the inhabitants of any small spot.
- Suggest other ways in which the theory might be tested.
Darwin disregarded certain pieces of evidence against his theory, assuming -- rightly, as it turned out -- that it was the auxiliary hypotheses employed in deriving the predictions that were wrong.
The main alternatives to Darwin's theory were -- and still are -- Lamarckism and creationism.
By what arguments would the following auxiliary hypotheses, if they were true, lead to predictions contrary to the evidence? (-- which would falsify the theory of evolution.) Why were they thought to be true, and how do we know today that they are not?
- Darwin himself did not believe that inherited characteristics could vary discontinuously: natura non facit saltum.
- And he did see the problem of evolution requiring more than the few million years which life was thought to have existed on earth:
With respect to the lapse of time not having been sufficient, ... this objection ... is one of the gravest yet advanced. I can only say, firstly, that we do not know at what rate species change as measured by years, and secondly, that many philosophers are not yet willing to admit that we know enough of the constitution of the universe and of the interior of our globe to speculate with safety on its past duration.
Jean Baptiste, chevalier de Lamarck (1744 -1829,) had a theory of evolution which depended on acquired characteristics being passed on from the individuals of one generation to their offspring.
The prevailing view at Darwin's time, as found in Genesis 1.24-25 and 2.18 in the Bible, was that species were fixed and that all of them had been created in substantially their present form; this is sometimes referred to as a 'catastrophic' account of the origin of species.
The success of Darwin's theory of evolution is an example of a 'scientific revolution' in a particular area of biology. In such a revolution there may be no new evidence: but as the paradigm shifts, the evidence comes to be interpreted in a different way.
- In the Bible, read Genesis 1.24-25 and 2.18. What do these passages tell us about the early Hebrew view of the origin of species?
- It seems that most cultures have their own creation stories. Try to find other such accounts of the origin of species, from other parts of the world.
- How would the long neck of giraffes, for example, be explained by holders of the following theories:
|i. creationism ||ii. Lamarckism ||iii. Darwinism
Thus Lucretius, in the 1st century B.C. already, had put forward an account involving the survival of the fittest:
And many species of animals must have perished at that time, unable by procreation to forge out the chain of posterity; for whatever you see feeding on the breath of life, either cunning or courage or at least quickness must have kept ... from its earliest existence.
Malthus in An Essay on the Principle of Population, 1798, had written on the limitation of resources and predicted a grim struggle for existence:
Someone who is born into a world which has already been taken into possession ... is not at all entitled to any nourishment. At nature's great table no place has been laid for him. Nature tells him to go, and does not hesitate to execute her command.
And precisely the kind of evidence which Darwin used to support his theory of evolution by natural selection had already been used by theologians in their 'Argument from Design', e.g. William Paley in his Natural Theology, 1802: specialist adaptation to widely different environments proves the wisdom of the God who designed all these so various creatures, and homologies between species just show that "we never come into the province of a different Creator."
One reason that Darwin's theory has given rise to so much resistance is of course that it 'threatens' the special position human beings have assumed they have, as either especially created by God, or as the product of a purposeful development, culminating in homo sapiens. Even A. R. Wallace, mentioned above as an early champion of evolution, recognising that the hunters and gatherers of the time when we evolved were biologically our equals, in the end refused to accept that our highest faculty, the mind, could be the result of evolution.
Although Darwin's theory of evolution, in a modern form, is now widely accepted, it was not only in the 19th century that Darwinism received a hostile reception from most of the Christian world.
Even today there are demands in certain states of the U.S. to allow equal time in biology classes at schools for evolution and 'scientific creationism' or 'creation science'. This has become an issue which has had to be settled in court a number of times.
A well known confrontation occurred back in 1925, known as the 'Tennessee Monkey Trial', where the State of Tennessee actually passed a law forbidding the teaching of evolutionary biology in its public schools.
In 1981 in the state of Arkansas it seemed that history was repeating itself. A bill was passed requiring that "public schools within this State shall give balanced treatment to creation-science and to evolution science." The matter went to court and one of the passages used as evidence was from a book by Duane T. Gush, Evolution: The Fossils Say No :
By 'creation' we mean the bringing into being of the basic kinds of plants and animals by the process of sudden, or fiat, creation described in the first two chapters of Genesis. Here we find the creation by God of the plants and animals, each commanded to reproduce after its own kind using processes which were essentially instantaneous. We do not know how God created, what processes he used, for God used processes which are not now operating anywhere in the natural universe. This is why we refer to divine creation as special creation. We cannot discover by scientific investigation anything about the creative processes used by God.
Does this passage actually support the creationists' claim that their view is as scientific
as the Darwinian? If not, why not?
Our law, our government, and our science continually require us to reason through a variety of complicated phenomena to the expected result. Even our games, such as chess, compel us to exercise all these faculties in a remarkable degree. Compare this with the savage languages, which contain no words for abstract conceptions; the utter want of foresight of the savage man beyond his simplest necessities; his inability to combine, or to compare, or to reason on any general subject that does not immediately appeal to the senses. ...
... Natural selection could only have endowed savage man with a brain a few degrees superior to that of an ape, whereas he actually possesses one very little inferior to that of a philosopher.
Wallace's argument that our highest mental faculties are useless in evolutionary terms and therefore cannot have arisen by natural selection, depends on certain assumptions, both about 'savages' and about 'philosophers'. Make these assumptions explicit and discuss whether they are valid.
It could be said that typically we give a scientific explanation of a phenomenon by specifying its cause: thus, we explain the falling of an apple, which we call the effect, by saying that it is caused by the gravitational force. And one might therefore say that science is the study of the causes of events.
However, as David Hume (1711 - 76) first pointed out, our belief in a necessary relation between cause and effect is based on custom and habit rather than reason or observation:
We have no other notion of cause and effect, but that of certain objects, which have been always conjoined together. ... We cannot penetrate into the reason of the conjunction. ... [And we presuppose] that instances, of which we have had no experience, must resemble those, of which we have had experience, and that the course of nature continues always uniformly the same.
(Hume was an empiricist philosopher from Scotland, whose sceptic philosophy restricted human knowledge to that which can be perceived by the senses.)
A Treatise of Human Nature (Book I), 1739.
Hume's analysis of causality, in a more refined form, has become the generally accepted account: we now think of causal relationships as determined by 'covering laws' in the scientific theories we hold, which means that as our theories change so will our ideas of what is the cause of what.
Suggest a 'covering law' to explain that striking a match causes it to light.
We no longer hold the following theories. How do we today believe those same events to be caused?
- According to Aristotle's physics, objects fall and rise because each object, according to its weight, has a natural level to which it tends to move.
- It used to be commonly believed that during a thunderstorm clouds collide, and that that is what gives rise to thunder and lightning.
- Copernicus, who knew that the earth and the other planets move around the sun, believed that they had to be pushed by angels to keep moving.
That causal relationships are a matter of the views one holds may be even more obvious in the social sciences: while some (on the political 'Right') believe that people are unemployed because they are lazy, others (on the 'Left') believe that people become lazy when they have been unemployed for long.
4. Limits of Predictability
As we have seen, prediction is an essential part of justifying claims of knowledge in science: by testing further predictions derived from our theories, we must perpetually lay them open to refutation; it is in this sense that scientific knowledge is only provisional.
But we don't do science just to increase our knowledge, we also apply that knowledge. We can use scientific knowledge precisely because it allows us to make predictions, and very often the predictions made by scientists have been very accurate and useful. Perhaps as a result, there is another wide-spread, if often unspoken, belief: that science will eventually enable us to predict everything, at least in principle if not in practice.
In its extreme form, this belief is that in a completely deterministic universe: that if we could at any point in time know the present state of the universe (or a closed system within it) completely, we would be able to calculate ahead to its state at any point in the future. Laplace expressed his belief in such a deterministic, 'clockwork'-universe when he wrote that "everything that has happened, everything that is happening and everything that will happen has been unalterably determined from the first instant."
However, science itself -- at least the scientific theories we hold today -- provides four sufficient reasons for rejecting that belief.
- While science is apparently quite successful in dealing with small, 'closed' systems, scientists have not been able to make accurate predictions for complicated systems, such as the earth's weather.
However, in any physical system, even the smallest influences will eventually make a significant difference: one particle at the edge of the known universe still exerts sufficient gravitational force on the molecules in a cube whose edge measures 10cm of gas that by the time the molecules have had an average of 50 collisions, one of them could be expected to be moving at about right angles to what its direction would have been if that particle hadn't been there (-- from a BBC programme.)
There is therefore no smaller closed system than the whole universe, and accurate prediction would require taking into account every particle in the universe.
- According to the uncertainty principle in quantum theory (Werner Heisenberg, 1925,) the position and momentum ( = mass . velocity ) of an object cannot both be accurately known simultaneously. This affects all objects, but only is observable in the case of objects of very small mass, such as elementary particles. The limitation is not due to inaccuracies in our measurements but is in the nature of things.
It is therefore not possible to know the state of the universe, or even of a small part of it, completely at any time.
Try to describe mechanisms, either natural or man-made, by which the indeterminacy at the level of particles due to the uncertainty principle could have macroscopic effects.
- Certain theories can make very accurate predictions -- but not of particular events, only of their probabilities: we can specify the half-life of a radioactive substance precisely, i.e. say when half of some quantity of it will have decayed, but not when any particular atom will split.
So even if we could know the state of the universe, or of a small part of it, completely at some time, our predictions could only be probabilistic.
- Much of the world is chaotic, in the following sense: apparently random phenomena, such as the dripping of a tap, turn out to have an underlying order -- but this order is not such that it enables us to make predictions. As a branch of science, chaos theory is fairly new, dating back to the 1970ies, although many of the phenomena it is investigating are not.
What follows is an attempt to explain the idea of chaos and the nature of the order it has.
- Physics has been very successful in predicting future states of certain systems, with simple equations, from their initial conditions: the equations governing these systems are such that despite small errors in the initial conditions, the solutions give good approximations.
- But prediction fails in the case of many real-life systems, because although the complex physical equations governing their behaviour can be set up precisely, they cannot then be solved mathematically (-- and not just not now, or not by us, but in principle.)
- Until some recent re-thinking, the assumption used to be held universally that one could predict future states of such real-life systems at least approximately, by solving curtailed versions of the complex equations governing them, and using these solutions as approximations;
- i.e. it used to be assumed that the inaccuracies resulting from curtailing the equations, to make them solvable, was no more serious than that due to small errors in the initial conditions for simple systems, (from which their future states could still be predicted quite well.)
- However, it now appears to be a characteristic of the uncurtailed versions of these equations governing real-life situations, that small errors in the initial conditions get magnified enormously as the system evolves (-- the 'butterfly effect';)
- i.e. the terms of complex equations, which had been assumed to make no big difference in the long run (or on the large scale,) and therefore to be such that they could be disregarded, have turned out to make a radical difference to the nature of the solutions of the equations.
- So these systems are 'chaotic': their future states must be calculated separately for each particular set of initial conditions (- the computing power for which has been available only recently): even a small change in initial conditions results in vastly different future states.
- One then finds that although the physical equations cannot be solved, they are such that the dependence of the future state on the initial conditions does follow certain kinds of patterns, which we can compute point by point -- these are what mathematicians call fractals;
- i.e. there is a distinction between arbitrariness and chaos: a system with certain kinds of local rules of development, even if we cannot predict its future global behaviour, will show a pattern in how it behaves -- the patterns of chaos are fractal shapes.
- A fractal is a set of points whose dimension is not an integer, but a fraction (-- hence the name): e.g. if a line is so convoluted that it is infinitely long between two points, then a point on it cannot be fixed by its distance from a given point -- but nor is such a line two-dimensional.
- The connection between this definition, and the role of fractals as the patterns of chaos, is that it is the infinitely repeated application of a simple rule that gives rise both to fractal shapes, (like ferns in nature or the Mandelbrot set,) and to the patterns in chaos.
For a very readable introduction, see James Gleick, Chaos: Making a New Science, 1987, even if the book reads rather like hagiography. (Hagiography is literature about the lives of saints and martyrs, in this case the mostly Californian saints and early martyrs of chaos theory.)
5. Applying Scientific Knowledge
A way of organizing the process of writing an essay or preparing a seminar is to divide it into four phases, with different purposes and rules:
- Brain-storming, i.e. generating ideas, being creative:
put forward any idea that comes to mind and make a quick note of it, do not try to organize or evaluate, let one idea lead to another ('piggy-backing,') aim for quantity rather than quality.
starting from the output of the brain-storming, divide the ideas into groups, fill gaps, add examples to fit categories, find categories to fit examples, concentrate on what is relevant to the topic and discard what is not.
starting from the output of the sorting and organizing, put the groups and the points within each group in an order, impose (or let the material suggest) a form of argument, decide on an introduction and a conclusion.
- Writing, or speaking:
starting from the output of the structuring, produce coherent text for others, taking care to make clear the line of your argument.
In one's actual work these four phases will usually not be sharply separated, so that one may some time go back to i. when one has found in iii. that a gap in the argument needs to be filled, but for practice it may be helpful to go through them explicitly some times.
In groups of four or five, one of whom needs to act as the 'group secretary' and write things down, follow the procedure described above to produce an outline for an essay or seminar on the following topic:
"Discuss the different ways in which science and technology are related. What roles do they have in our society, and what values govern their progress?"
'Green' Readings :
[Late 17c in this sense; from Lat. scientia, knowledge.]
Knowledge, wisdom; an important part of relating to the natural world and of understanding that relationship. 'Science,' however, has largely become a victim of Western dualism and the ideas of progress that go with it. From the early nineteenth century until recently, when there have been some glimmers of a hopeful alternative viewpoint, 'science' has been a way of looking at the world which only acknowledges the truth of something when and if it can be observed, measured, and operated on using the 'scientific method' [1854.] ... Many green-thinkers are convinced that a great deal of modern science, in the way it has been formulated and controlled, is antithetical to a holistic approach, and that the dichotomy is unbridgeable. 'Socially irresponsible science not only pollutes our rivers, air and soil, produces CS gas for Northern Ireland, defoliants for Vietnam and stroboscopic torture devices for police states. It also degrades, both mentally and physically, those at the point of production, as the objectivisation of their labour reduces them to mere machine appendages' (Mike Cooley, 1987.) Some feminists, equating science with patriarchal power, have reached the same conclusion: 'Science is men's studies and cannot be modified, and ... a "woman-centred science" would be so radically different that it would no longer be invested with the meaning of "science" as we know it' (Dale Spender, 1981.) ... Though many scientists either declare or imply that their science is intrinsically neutral, there is very little science which is not funded by concerns whose main interest is commercial viability, and a great deal of scientific research and development continues because multinationals and militaristic governments fund it and because scientists choose to do it, not 'because it is there to be done.' 'His face was wreathed in a smile of almost angelic beauty. He looked as though his inner gaze were fixed upon a world of harmonies. But in fact, as he told me later, he was thinking about a mathematical problem, whose solution was essential to the construction of a new type of H-bomb. ... He had never visited Hiroshima or Nagasaki, even though he had been invited. ... To him research for nuclear weapons was just pure higher mathematics untrammelled by blood, poison and destruction. All that, he said, was none of his business' (Robert Jungk, 1956.) Yet ecologists, meteorologists, nature reserve wardens, appropriate technologists, new physicists, and many of the green-thinkers who have drawn our attention to the perils of dangerous technologies are scientists too, and their careful skills are needed. Is it possible, knowing what we now know, to return science to its ancient status of wisdom and deep knowing? 'Science and technology cannot be humanely applied in an inherently inhuman society, and the contradictions for scientific workers in the application of their abilities will grow and, if properly articulated, will lead to a radicalisation of the scientific community' (Mike Colley, op. cit.)
[17c; from Gk. technologia, the systematic study and use of skills.]
Using our knowledge about the world to useful and non-harmful ends. This green definition is not, however, widely held; more common is 'the application of practical or material sciences to industry or commerce' (Collins, 1986.) In the green version, technology predates science by millennia and belies the current practice always to link the two; the great debate about the usefulness of technology hinges on its subversion by scientism and the scientific imperative, which since the nineteenth century has been intimately linked with capitalism, centralisation, and the idea of progress. ... The questions for green-thinkers are: Which technologies are environmentally sound? Who is technology benefiting? Who is making decisions about which technologies are developed and which not? 'Ecologists are not hostile to technology per se, and the use of advanced technologies of many kinds is essential to the development of an ecological society. ... It is a matter of choice whether technology works for the benefit of people or perpetuates certain problems, whether it provides greater equity and freedom of choice or merely intensifies the worst aspects of our industrial society. ...' (Jonathan Porritt, 1984.)
Complete yet ultimately mistaken faith in the scientific method ...; sometimes contrasted with holism.
[1926; from Gk. holos, whole.]
The belief that systems can only be properly understood when seen as a unified whole rather than as a sum of their separate parts. '... In Holism and Evolution, Smuts called attention to an invisible but powerful organizing principle inherent in nature. If we did not look at wholes, if we failed to see nature's drive toward ever higher organization, we would not be able to make sense of our accelerating scientific discoveries' (Marilyn Ferguson, 1981.) ...
John Button, A Dictionary of Green Ideas, 1988.
These two lectures are intended as a lead-in to the topic, and it will in any case be helpful to introduce the concepts and ideas presented here at the outset.
To review the lectures, students are asked in Exercise 1.2. to fill gaps in incomplete sentences, in effect summarising the lectures.
I. What Do Scientists Do ?
- Introduction: [2nd lecture more interesting.]
- The Topic of Th.o.K.:
what in different areas counts as understanding,
- from mathematics: being able to prove from principles/axioms,
- to human actions: in terms of motives, beliefs, ...
- Understanding in Science:
- explaining in terms of general laws:
e.g. why does an apple fall?
- interest dependence:
e.g. why did the gun fire? -- someone pulled the trigger,
but: why was JFK shot? -- someone pulled the trigger (?!)
- explanatory relevance:
e.g. police: why do you keep robbing banks ?
thief: because that is where the money is (?!)
- The Subject Matter of Science:
- science is EMPIRICAL,
- i.e. derived from experience and observation, of the outside world.
- The 'Naive' Theory: [Give plenty of examples.]
- Collection of Evidence:
- observation and recording of all facts;
- quantification (measuring) and analysis.
- Generalization to Scientific Laws:
- scientific laws are universal statements:
"whenever ... then ... " --
- INDUCTION is the process of going from particular to general statements.
- Hence Science is Objective:
its statements have been 'proved' true.
- Criticisms of the Naive View
- Need Initial HYPOTHESES:
- for not all facts can be collected;
- induction is not a mechanical procedure:
the initial hypotheses are invented;
- need creativity, use modelling, analogy, etc. --
e.g. Kekulé's dream, of a snake biting its own tail, leading to the discovery/ invention of the structure of benzene;
- Scientific Laws Cannot Be Proved:
- empirical universal statements cannot be verified, i.e. they cannot be shown to be true,
- but they are capable of FALSIFICATION:
a single observation is enough;
- Karl Popper (Austrian-born British scientist, anti-Marxist philosopher, 1902 -1994):
a statement not testable at least in principle cannot even be proposed as a scientific hypothesis;
- so scientific knowledge is only PROVISIONAL;
scientific laws and theories are the 'successful' hypotheses and models
(-- which may be in terms of theoretical entities.)
- Hence TESTING:
- derive predictions --
DEDUCTION is the process of going from general to particular statements;
prediction is an essential aspect of science;
- again, experiments to test the hypothesis are invented;
logic does not generate implications or proofs, it only safeguards their soundness;
- (unlike in science teaching,) experiments serve to test hypothesis.
- The OBJECTIVITY of Science:
- while hypotheses/theories can be freely invented and proposed,
they are accepted only if they pass critical scrutiny;
- require repeatability,
by anybody, anywhere and at any time;
- i.e. distinguish how scientists think from what will become scientific knowledge.
- Need for AUXILIARY HYPOTHESES:
- the outcome of an experiment may not be conclusive counter-evidence,
- e.g. Brahe: if Copernicus were right, (and if the stars are close enough,) a yearly parallactic movement of the stars should be observable.
- The Improved View:
the 'hyothetico-deductive method' of science.
II. How Has Science Got Here ?
the 'hyothetico-deductive method' of science.
- How Does Science Progress ?
(Thomas Kuhn, 1962)
- Taking a step back ...
- history of science:
science has not just been cumulative,
- different past theories embodied incommensurate views of the world --
- hence one must distinguish:
- 'Normal Working' of Science:
- within a paradigm, i.e. a coherent tradition:
writing of textbooks, education;
- defines the questions that can be asked, legitimate methods, etc.
e.g. not -- at present -- 'super-natural' phenomena;
- like puzzle-solving:
assumes every problem can be solved within it,
limited by rules which allow only certain moves,
cumulative, but not always intrinsically valuable;
- no such paradigms in other fields:
e.g. 'expectations' as given from outside economics,
in philosophy/ literature/ ... different schools co-exist.
- 'Scientific Revolutions':
anomaly, when nature is found to violate the ruling paradigm:
e.g. light as particle not just wave,
new discoveries: oxygen (at the time of phlogiston),
new theories: Copernican astronomy, relativity;
- at first: attempt at ad hoc solutions,
and the paradigm may survive;
- competition of views:
no formal evaluation procedure,
since these depend on the paradigm:
promise of theory, status of individuals, aesthetic appeal, ...;
- may change to a new, incompatible view of the field:
paradigm shift -- cf. Necker's cube:
new methods, new goals, new reading of evidence, ...;
adherents of the previous paradigm change their minds, die out;
- then return to normal science:
new textbooks 'hide' the revolutions and past paradigms.
- 'Pre-History' of a Science,
e.g. alchemy before chemistry,
creation stories before theory of evolution:
- no paradigm yet --
many rival theories/ individuals,
no agreement even on what is relevant,
- like during a revolution: no procedure for evaluation,
- appeal to religion/ the occult, etc.
- What Is Science ?
- Taking another step back ...
- historically, the activities that have developed into modern science have had different purposes,
(cf. Michel Foucault, French philosopher, 1926 -1984;)
- have to consider it as an activity in a given society,
for particular social purposes,
governed by specific rules -- cf. chess;
- while the scientific way of thinking has achieved dominance world-wide, it originates from a particular development in Western society:
- Middle Ages:
- to prove God's existence and benevolence from nature:
- understanding = relating regularities to God's will;
e.g. seven planets, corresponding to the seven orifices in our heads.
- to catalogue and categorize all there is, completely:
- understanding = knowing the place of each thing in the totality.
- Industrial Revolution:
- to serve technological progress, (which is clearly definable):
- understanding = explaining things in terms of general laws, with accuracy of prediction as the sole criterion.
- Late 20th Century (?):
- to advance society (-- not yet clearly defined):
- cf. the emergence of the social sciences, which do not share the values of science as conceived according to the previous paradigm;
- and the realization that science influences as well as -- or even by -- observing;
- and today already greater responsibility to society is demanded of scientists.
Teaching Notes :
1. What Do Scientists Do? and: How Has Science Got Here?
This should allow students to see how much of the lectures they have understood and remember. The completed Exercise is a summary of the lectures. (It might be necessary to provide, on the board, say, an alphabetical list of all the words to be substituted.)
- general laws, "Whenever conditions C, then event E."
- induction, deduction, predictions
- falsified, falsifiable
- provisional, falsification, testing
- empirical, creativity, objective, repeatability
- revolutions, normal science
- paradigm, revolution, pre-science
Ask the question: is there any experience from which I could conclude/ deduce that the proposition is true, or false?
Note (i) that whether the proposition is true or false is irrelevant to its verifiability or falsifiability, (ii) that if a proposition is verifiable, it is also falsifiable, (I think,) and (iii) that what is required is being falsifiable or verifiable in principle, not necessarily practically.
- falsifiable only,
- falsifiable only,
2. Case Study: Darwin's Theory of Evolution
- "According to Popper, the theory claimed that evolution proceeds by survival of the fittest, but it defined 'the fittest' as those who survive and reproduce the most. This turns the theory into an empty claim that the fittest are the fittest, ...
... [But] Evolutionary biologists do in fact have a way of identifying adaptations independent of rates of reproduction, so they need not define fitness in terms of it. First, they have independent means of determining what the needs of organisms are: food, oxygen, water, and so on; ... Second, biologists have means of determining the extent to which varying behaviours, organs, tissues, cells, and so on, contribute to meeting these needs in different environments. ... [e.g.] why arctic organisms like polar bears have a larger volume-to-surface-area ratio than their conspecifics in more temperate zones" (Alexander Rosenberg, Philosophy of Social Science, 1988.)
A similar problem exists with the proposition that "Every event has a cause" - faced with an apparently uncaused event, we would keep looking for a cause rather than reject that proposition.
- "... we already see how it [the theory] entails extinction; and how largely extinction has acted in the world's history, geology plainly declares." -- this was a new insight:
John Wesley, in 1770: "Death is never permitted to destroy the most inconsiderable species," and
Thomas Jefferson: "the economy of nature" is such that "no instance can be produced of her having permitted any one race of animals to become extinct."
A well-known example of natural selection and survival of the fittest in action is that of a certain species of moths: to avoid being detected and eaten by birds, they had evolved so that almost all had a light colour similar to that of the bark of certain trees on which they could sit camouflaged.
What has been observed is that these moths became much darker in the North of England from the middle of the 19th century, as pollution blackened the bark of trees, but that this trend has been reversed recently: with the decline of heavy industry and less coal-burning, it has an advantage again for a moth to be lighter in colour.
|a. ||natural selection & |
natura non fecit saltum
|characteristics of each species converge
(-- contrary to experience !)
|b. ||Darwinism & |
age of the earth is only a few million years
||species have not changed much and hardly any have become extinct yet
(-- contrary to experience !)
|In fact, the earth's age was vastly underestimated at the time because radioactivity, which keeps the earth's interior hotter, had not yet been discovered.
Wallace "saw a chasm between the simple, concrete, here-and-now thinking of foraging people and the abstract rationality exercised in modern pursuits like science, mathematics and chess. But there is no chasm. Wallace, to give him his due, was ahead of his time in realizing that foragers were not on the lower rungs of some biological ladder. But he was wrong about their language, thought and lifestyle. Prospering as a forager is a more difficult problem than doing calculus or playing chess."
And conversely, "Natural selection ... did not shape us to earn good grades in science class or to publish in refereed journals. It shaped us to master the local environment, and that led to discrepancies between how we naturally think and what is demanded in the academy" (Pinker.) So not only are the 'savages' more like the 'philosophers' than Wallace thought, the 'philosophers' are not so different from the 'savages'.
When one ball strikes another and apparently causes it to move, we cannot see any force that literally connects the two movements. All we can know from observation is that certain events are constantly conjoined in our experience, and we expect, though we cannot prove it, that the future will be like the past. Thus, Hume said, causal reasoning is merely the expectation that constantly conjoined kinds of events will remain so in future, but we have no way of telling why events are so conjoined.
The covering law might be something like: "Whenever you strike a well-made match hard enough against a properly prepared surface, then, other conditions being favourable, it will light" (from Donald Davidson, "Causal Relations", 1967,) but it would require much more detail to make it 'tight'.
- The gravitational force on a more massive object (like a stone) is stronger than that on a less massive one (like the air.)
- Lightning causes air to suddenly heat up and expand, and the resulting pressure waves are the sound of the thunder.
- Objects require no force to keep them in their state of motion: it is stopping a moving object that requires a force, (such as friction.)
Charles Darwin, The Origin of Species, 1858. Penguin.
Antony Flew, Darwinian Evolution, 1984. Paladin.
James Gleick, Chaos: Making a New Science, 1987. Heinemann.
Carl G. Hempel, Philosophy of Natural Science, 1966. Prentice-Hall.
Thomas S. Kuhn, The Structure of Scientific Revolutions, 1962, 1970. University of Chicago Press.
Karl Popper, The Logic of Scientific Discovery, 1934 (1959,) 1972. Hutchinson.