Philosophy of science 4 Questions about the origins of the Earth exhibit this contrast of approach most clearly. Standard science has an explanation of the birth of the solar system that shows how gravitational forces within clouds of gas would condense the gases to stars and planets. The laws of nature we have discovered allow us to trace back the history of the universe to its earliest moments.Observation of the red-shift of galaxies allows us to formulate Hubble's law relating the speed of the recession of those galaxies to their distance.This in turn gives us some idea of the rate of expansion of the universe and hence its age.The creationists have nothing to say along such lines.The Earth and Sun and life were created simultaneously,several thousand years ago,as an act of God.How do we know this? Judge Overton quotes a leading creationist authority: ...it is...quite impossible to determine anything about the Creation through a study of present processes,because present processes are not creative in character.If man wishes to know anything about Creation (the time of Creation,the duration of Creation,the order of Creation,the methods of Creation,or anything else)his sole source of true information is that of divine revelation.God was there when it happened.We were not there...Therefore we are completely limited to what God has seen fit to tell us,and this information is in His written Word.This is our textbook on the science of Creation! Such an approach to the facts of creation is scarcely "tentative".Not only is it the final word,it is the Word.If creation were not subject to natural laws,then no amount of scientific investigation could have any bearing on it.This aspect of creationism is independent of natural explanation.It has no need of being tentative.Faith may be strong or it may be weak,but it is not a hypothesis.As creationism is not a hypothesis that invokes natural law,it is not open to amendment or refutation in the face of experience. The above quotation makes it clear that,as creation is quite a different sort of happening from anything occurring today,no observation of the latter could bear on claims about the former.The point of remarks such as these is not to refute any belief in divine creation,but to examine the claim that such beliefs can be scientific.There may be non- scientific knowledge of and justification for beliefs in creation;but that is another question.It may be worth remarking that there are few,if any,people who have adopted creationism without being religious and because of the supposedly scientific arguments for it. Creationists are fond not only of displaying the scientific credentials of their arguments but also of pointing out that evolutionists depend upon faith as much as anyone.This refers to the fact that there are unsolved problems concerning evolution.In the face of such difficulties,the scientists'belief in evolution must be a matter of faith. While most of these unsolved anomalies are in fact spurious or have already been solved (e.g.Kelvin's objection).it must be admitted that there are others for which a satisfactory solution remains to be found.For instance,the processes whereby life emerged from the primaeval soup are poorly understood.While we know how amino acids,the building blocks of organic molecules,can be created in a primitive atmosphere,there is a problem with understanding the origin of proteins.The interaction of proteins is not merely chemical but also depends on their large-scale architecture.It is not clear how proteins
Questions about the origins of the Earth exhibit this contrast of approach most clearly. Standard science has an explanation of the birth of the solar system that shows how gravitational forces within clouds of gas would condense the gases to stars and planets. The laws of nature we have discovered allow us to trace back the history of the universe to its earliest moments. Observation of the red-shift of galaxies allows us to formulate Hubble’s law relating the speed of the recession of those galaxies to their distance. This in turn gives us some idea of the rate of expansion of the universe and hence its age. The creationists have nothing to say along such lines. The Earth and Sun and life were created simultaneously, several thousand years ago, as an act of God. How do we know this? Judge Overton quotes a leading creationist authority: …it is…quite impossible to determine anything about the Creation through a study of present processes, because present processes are not creative in character. If man wishes to know anything about Creation (the time of Creation, the duration of Creation, the order of Creation, the methods of Creation, or anything else) his sole source of true information is that of divine revelation. God was there when it happened. We were not there… Therefore we are completely limited to what God has seen fit to tell us, and this information is in His written Word. This is our textbook on the science of Creation!4 Such an approach to the facts of creation is scarcely “tentative”. Not only is it the final word, it is the Word. If creation were not subject to natural laws, then no amount of scientific investigation could have any bearing on it. This aspect of creationism is independent of natural explanation. It has no need of being tentative. Faith may be strong or it may be weak, but it is not a hypothesis. As creationism is not a hypothesis that invokes natural law, it is not open to amendment or refutation in the face of experience. The above quotation makes it clear that, as creation is quite a different sort of happening from anything occurring today, no observation of the latter could bear on claims about the former. The point of remarks such as these is not to refute any belief in divine creation, but to examine the claim that such beliefs can be scientific. There may be nonscientific knowledge of and justification for beliefs in creation; but that is another question. It may be worth remarking that there are few, if any, people who have adopted creationism without being religious and because of the supposedly scientific arguments for it. Creationists are fond not only of displaying the scientific credentials of their arguments but also of pointing out that evolutionists depend upon faith as much as anyone. This refers to the fact that there are unsolved problems concerning evolution. In the face of such difficulties, the scientists’ belief in evolution must be a matter of faith. While most of these unsolved anomalies are in fact spurious or have already been solved (e.g. Kelvin’s objection), it must be admitted that there are others for which a satisfactory solution remains to be found. For instance, the processes whereby life emerged from the primaeval soup are poorly understood. While we know how amino acids, the building blocks of organic molecules, can be created in a primitive atmosphere, there is a problem with understanding the origin of proteins. The interaction of proteins is not merely chemical but also depends on their large-scale architecture. It is not clear how proteins Philosophy of science 4
Introduction:the nature of science 5 could come into being and replicate.Nonetheless,a scientist's rational adherence to a theory does not require it to be flawless,let alone be without a problem.Scientists require a theory to be a good,preferably the best available,explanation of a range of important phenomena.This in turn depends on the theory's ability to generate and maintain strategies for solving problems. So the sign of a successful theory is not the absence of problems but its ability to solve those problems which do arise.An instance of this is explained by Stephen Jay Gould in his famous essay The panda's thumb.The giant panda appears to have six fingers,one of which is an opposable thumb useful for gripping things such as bamboo stalks.This is very odd.Primates,but few other animals,have an opposable thumb.According to the story of primate evolution this is a development of one of five digits.Bears have the same five digits but have not developed any of them into a thumb,because their paws have evolved,like those of many animals,for the purpose of running.Where does the panda's thumb come from?Being a sixth finger it cannot have developed from one of the preexisting five,as in the case of the human thumb.But the evolution of a completely new finger,though perhaps possible,seems unlikely.(Perhaps one might wonder if the panda did not evolve but was put on Earth properly designed for its purpose.)It turns out that the panda's thumb is not a true finger at all.There are no new bones involved.Rather an existing bone,part of the panda's wrist,has become elongated until it is able to function like an opposable thumb.Evolutionarily this is highly plausible.Gould's point is that nature does not show evidence of design but the adaptation for a new purpose of organs and limbs that first evolved with a different purpose (which he says is more like tinkering than design).My point,more broadly,is that the ability of evolutionary theory to cope with such oddities is the reason why scientists find it credible.As long as it continues to be successful in this way the appearance of new problems,far from being a sign of failure,is what provides fuel for growing knowledge.Of course it may be that the problems begin to pile up without the recompense of adequate solutions,and then we may be in a different ballpark.This is an interesting issue and we shall come back to it later in this book. Judge Overton's reasons for rejecting creation "science"are useful to us not only in providing criteria for deciding what may or may not properly be called science,but also because they highlight many of the ideas and notions that we as philosophers of science must investigate.His analysis says that science should concern natural laws or explanations in terms of natural law.But what is a natural law and what counts as an explanation?While these concepts may have been clear enough for the judge's purposes, we shall see that once one looks at them at all closely all sorts of problems begin to arise. A claim of the creationists which the court rejected was that living things come in distinct kinds.The judge and the witnesses against the State of Arkansas seemed to think that this concept is unscientific.Perhaps one can see why,given the creationists'use of it. In their view,mankind belongs to a different kind from other primates.Yet they also claim that all the different species of bats (over 800 of them forming a diverse order) belong to a single kind.This seems an odd and tendentious notion of kind.But surely there is some sense in saying that chemical elements make up distinct kinds?And what about different species?We shall see whether there is a need for a notion of natural kind and what that notion is
could come into being and replicate. Nonetheless, a scientist’s rational adherence to a theory does not require it to be flawless, let alone be without a problem. Scientists require a theory to be a good, preferably the best available, explanation of a range of important phenomena. This in turn depends on the theory’s ability to generate and maintain strategies for solving problems. So the sign of a successful theory is not the absence of problems but its ability to solve those problems which do arise. An instance of this is explained by Stephen Jay Gould in his famous essay The panda’s thumb. The giant panda appears to have six fingers, one of which is an opposable thumb useful for gripping things such as bamboo stalks. This is very odd. Primates, but few other animals, have an opposable thumb. According to the story of primate evolution this is a development of one of five digits. Bears have the same five digits but have not developed any of them into a thumb, because their paws have evolved, like those of many animals, for the purpose of running. Where does the panda’s thumb come from? Being a sixth finger it cannot have developed from one of the preexisting five, as in the case of the human thumb. But the evolution of a completely new finger, though perhaps possible, seems unlikely. (Perhaps one might wonder if the panda did not evolve but was put on Earth properly designed for its purpose.) It turns out that the panda’s thumb is not a true finger at all. There are no new bones involved. Rather an existing bone, part of the panda’s wrist, has become elongated until it is able to function like an opposable thumb. Evolutionarily this is highly plausible. Gould’s point is that nature does not show evidence of design but the adaptation for a new purpose of organs and limbs that first evolved with a different purpose (which he says is more like tinkering than design). My point, more broadly, is that the ability of evolutionary theory to cope with such oddities is the reason why scientists find it credible. As long as it continues to be successful in this way the appearance of new problems, far from being a sign of failure, is what provides fuel for growing knowledge. Of course it may be that the problems begin to pile up without the recompense of adequate solutions, and then we may be in a different ballpark. This is an interesting issue and we shall come back to it later in this book. Judge Overton’s reasons for rejecting creation “science” are useful to us not only in providing criteria for deciding what may or may not properly be called science, but also because they highlight many of the ideas and notions that we as philosophers of science must investigate. His analysis says that science should concern natural laws or explanations in terms of natural law. But what is a natural law and what counts as an explanation? While these concepts may have been clear enough for the judge’s purposes, we shall see that once one looks at them at all closely all sorts of problems begin to arise. A claim of the creationists which the court rejected was that living things come in distinct kinds. The judge and the witnesses against the State of Arkansas seemed to think that this concept is unscientific. Perhaps one can see why, given the creationists’ use of it. In their view, mankind belongs to a different kind from other primates. Yet they also claim that all the different species of bats (over 800 of them forming a diverse order) belong to a single kind. This seems an odd and tendentious notion of kind. But surely there is some sense in saying that chemical elements make up distinct kinds? And what about different species? We shall see whether there is a need for a notion of natural kind and what that notion is. Introduction: the nature of science 5
Philosophy of science 6 Judge Overton says that a scientific theory should be both testable and falsifiable.Are these different or the same?Sir Karl Popper maintained that a theory could only be tested by attempting to falsify it.Success in passing such tests corroborates a theory.But much of the evidence for Darwin's hypotheses came from the fossil record.Creationists frequently point out the existence of gaps in the fossil record-the lack of fossils for intermediate evolutionary types.Darwin himself was unconcerned by this-the fossil record is just incomplete.And so the existence of gaps should not be taken as a refutation.But,on the other hand,the existence of expected fossils is positive evidence. So observations of fossils could confirm but not refute the Darwinian thesis.What then is falsifiability?And when is a theory confirmed by evidence? When we were discussing laws,explanations,and natural kinds we were concerned with the subject matter,in the most general terms,of a scientific theory.Now we have come to questions like:How may we falsify or confirm a theory?When is a scientific belief justified?When does a scientific belief amount to knowledge?The most extraordinary thing about science is the depth and range of the knowledge it claims to be able to give us,and it is about this knowledge that the philosophical puzzles arise. Without belittling the wisdom of societies without modern science,one may still wonder at the achievement-or arrogance,if you prefer-of scientists who claim some understanding of what happened during the first few moments of the existence of the universe,of the laws that govern the motions of the stars and planets,of the forces and processes that gave birth to life on Earth,and of the structure,functioning,and origin of living organisms. The story of why this knowledge came about when and where it did,is one for the historian and sociologist of science.Our job as philosophers is not to ask where this knowledge came from,but to look carefully at that knowledge itself and ask:What is it? Is scientific knowledge really as it first appears to us to be?This enquiry I will break down into two parts.The first asks,What is scientific knowledge knowledge of?The straightforward answer is:science is knowledge of why things are the way they are,of the kinds of thing there are to be found in nature.and of the laws governing these things. We shall see that things are not so simple when it comes to saying what a law of nature is,what an explanation is,and what a natural kind is.Indeed,we shall see that the idea that science provides knowledge of a reality independent of humans is itself intensely problematic.These issues will occupy us in Chapters 1 to 4. Having considered what scientific knowledge is knowledge of,the second part of our enquiry goes on to ask what right we have to think of it as knowledge at all?Perhaps what we call knowledge is not knowledge at all-perhaps it just appears to be knowledge.What would make the difference?These questions come in the second part this book (Chs.5-8),since the importance of our knowledge as well as our route to it depend upon what it is we are supposed to know about.Nonetheless.while investigating the concepts of law,kind,and explanation,we will need to bear in mind quite general problems that face anyone who claims to have scientific knowledge.Philosophy is best approached through its problems and puzzles,and the philosophy of science is no exception to this.So we shall start by introducing two puzzles about scientific knowledge (which I will call Hume's problem and Goodman's problem).They both concern induction,which is at the heart of scientific reasoning
Judge Overton says that a scientific theory should be both testable and falsifiable. Are these different or the same? Sir Karl Popper maintained that a theory could only be tested by attempting to falsify it. Success in passing such tests corroborates a theory. But much of the evidence for Darwin’s hypotheses came from the fossil record. Creationists frequently point out the existence of gaps in the fossil record—the lack of fossils for intermediate evolutionary types. Darwin himself was unconcerned by this—the fossil record is just incomplete. And so the existence of gaps should not be taken as a refutation. But, on the other hand, the existence of expected fossils is positive evidence. So observations of fossils could confirm but not refute the Darwinian thesis. What then is falsifiability? And when is a theory confirmed by evidence? When we were discussing laws, explanations, and natural kinds we were concerned with the subject matter, in the most general terms, of a scientific theory. Now we have come to questions like: How may we falsify or confirm a theory? When is a scientific belief justified? When does a scientific belief amount to knowledge? The most extraordinary thing about science is the depth and range of the knowledge it claims to be able to give us, and it is about this knowledge that the philosophical puzzles arise. Without belittling the wisdom of societies without modern science, one may still wonder at the achievement—or arrogance, if you prefer—of scientists who claim some understanding of what happened during the first few moments of the existence of the universe, of the laws that govern the motions of the stars and planets, of the forces and processes that gave birth to life on Earth, and of the structure, functioning, and origin of living organisms. The story of why this knowledge came about when and where it did, is one for the historian and sociologist of science. Our job as philosophers is not to ask where this knowledge came from, but to look carefully at that knowledge itself and ask: What is it? Is scientific knowledge really as it first appears to us to be? This enquiry I will break down into two parts. The first asks, What is scientific knowledge knowledge of? The straightforward answer is: science is knowledge of why things are the way they are, of the kinds of thing there are to be found in nature, and of the laws governing these things. We shall see that things are not so simple when it comes to saying what a law of nature is, what an explanation is, and what a natural kind is. Indeed, we shall see that the idea that science provides knowledge of a reality independent of humans is itself intensely problematic. These issues will occupy us in Chapters 1 to 4. Having considered what scientific knowledge is knowledge of, the second part of our enquiry goes on to ask what right we have to think of it as knowledge at all? Perhaps what we call knowledge is not knowledge at all—perhaps it just appears to be knowledge. What would make the difference? These questions come in the second part this book (Chs. 5–8), since the importance of our knowledge as well as our route to it depend upon what it is we are supposed to know about. Nonetheless, while investigating the concepts of law, kind, and explanation, we will need to bear in mind quite general problems that face anyone who claims to have scientific knowledge. Philosophy is best approached through its problems and puzzles, and the philosophy of science is no exception to this. So we shall start by introducing two puzzles about scientific knowledge (which I will call Hume’s problem and Goodman’s problem). They both concern induction, which is at the heart of scientific reasoning. Philosophy of science 6
Introduction:the nature of science 7 What is induction? To set the stage then for these puzzles,I shall say something about what induction is.As the nature of induction is so puzzling,it would be foolish to attempt to define it.But some rough descriptions will give you the idea.We use "induction"to name the form of reasoning that distinguishes the natural sciences of chemistry,meteorology,and geology from mathematical subjects such as algebra,geometry,and set theory.Let us look then at how the way in which scientific knowledge is gained differs from the reasoning that leads to mathematical understanding.One distinction might be in the data used.For instance, while knowledge in the natural sciences depends upon data gained by observation,the practitioners of mathematical subjects do not need to look around them to see the way things actually are.The chemist conducts experiments,the geologist clambers up a rock face to observe an unusual rock stratum,and the meteorologist waits for data from a weather station,whereas the mathematician is content to sit at his or her desk,chew a pencil,and ruminate.The mathematician seems to have no data,relying instead on pure thought to conjure up ideas from thin air.Perhaps this is not quite right,as the mathematician may be working with a set of axioms or problems and proofs laid down by another mathematician,or indeed with problems originating in real life or in the natural sciences,for instance Euler's Konigsberg bridge problem or some new theory required by subatomic physics.These things are not quite like the data of geology or the experimental results of chemistry,but let us agree that they at least constitute a basis or starting point for reasoning that will lead,we hope,to knowledge. What really is different is the next stage.Somehow or other the scientist or mathematician reaches a conclusion about the subject matter,and will seek to justify this conclusion.In the case of the scientist the conclusion will be a theory,and the data used to justify it are the evidence.The mathematician's conclusion is a theorem justified by reference to axioms or premises.It is the nature of the justification or reasoning that differentiates the two cases;the mathematician and the scientist use different kinds of argument to support their claims.The mathematician's justification will be a proof.A proof is a chain of reasoning each link of which proceeds by deductive logic.This fact lends certainty to the justification.If what we have really is a mathematical proof,then it is certain that the theorem is true so long as the premises are true.Consequently,a proof is final in that a theorem once established by proof cannot be undermined by additional data.No one is going to bring forward evidence contrary to the conclusion of Euclid's proof that there is no largest prime number.'This contrasts with the scientific case.For here the support lent by the data to the theory is not deductive.First,the strength of justification given by evidence may vary.It may be very strong,it may be quite good evidence,or it may be very weak.The strength of a deductive proof does not come by degree.If it is a proof,then the conclusion is established;if it is flawed,then the conclusion is not established at all.And,however strongly the evidence is shown to support a hypothesis,the logical possibility of the hypothesis being false cannot be ruled out.The great success of Newtonian mechanics amounted to a vast array of evidence in its favour,but this was not sufficient to rule out the possibility of its being superseded by a rival theory
What is induction? To set the stage then for these puzzles, I shall say something about what induction is. As the nature of induction is so puzzling, it would be foolish to attempt to define it. But some rough descriptions will give you the idea. We use “induction” to name the form of reasoning that distinguishes the natural sciences of chemistry, meteorology, and geology from mathematical subjects such as algebra, geometry, and set theory. Let us look then at how the way in which scientific knowledge is gained differs from the reasoning that leads to mathematical understanding. One distinction might be in the data used. For instance, while knowledge in the natural sciences depends upon data gained by observation, the practitioners of mathematical subjects do not need to look around them to see the way things actually are. The chemist conducts experiments, the geologist clambers up a rock face to observe an unusual rock stratum, and the meteorologist waits for data from a weather station, whereas the mathematician is content to sit at his or her desk, chew a pencil, and ruminate. The mathematician seems to have no data, relying instead on pure thought to conjure up ideas from thin air. Perhaps this is not quite right, as the mathematician may be working with a set of axioms or problems and proofs laid down by another mathematician, or indeed with problems originating in real life or in the natural sciences, for instance Euler’s Königsberg bridge problem6 or some new theory required by subatomic physics. These things are not quite like the data of geology or the experimental results of chemistry, but let us agree that they at least constitute a basis or starting point for reasoning that will lead, we hope, to knowledge. What really is different is the next stage. Somehow or other the scientist or mathematician reaches a conclusion about the subject matter, and will seek to justify this conclusion. In the case of the scientist the conclusion will be a theory, and the data used to justify it are the evidence. The mathematician’s conclusion is a theorem justified by reference to axioms or premises. It is the nature of the justification or reasoning that differentiates the two cases; the mathematician and the scientist use different kinds of argument to support their claims. The mathematician’s justification will be a proof. A proof is a chain of reasoning each link of which proceeds by deductive logic. This fact lends certainty to the justification. If what we have really is a mathematical proof, then it is certain that the theorem is true so long as the premises are true. Consequently, a proof is final in that a theorem once established by proof cannot be undermined by additional data. No one is going to bring forward evidence contrary to the conclusion of Euclid’s proof that there is no largest prime number.7 This contrasts with the scientific case. For here the support lent by the data to the theory is not deductive. First, the strength of justification given by evidence may vary. It may be very strong, it may be quite good evidence, or it may be very weak. The strength of a deductive proof does not come by degree. If it is a proof, then the conclusion is established; if it is flawed, then the conclusion is not established at all. And, however strongly the evidence is shown to support a hypothesis, the logical possibility of the hypothesis being false cannot be ruled out. The great success of Newtonian mechanics amounted to a vast array of evidence in its favour, but this was not sufficient to rule out the possibility of its being superseded by a rival theory. Introduction: the nature of science 7
Philosophy of science 8 All these differences between mathematics and the natural sciences characterize the distinction between deductive and non-deductive reasoning.Not only mathematical reasoning is deductive.For example,the following argument is deductive: All mammals suckle their young; otters are mammals; therefore otters suckle their young. The next is deductive too: Duck-billed platypuses do not suckle their young; platypuses are mammals; therefore not all mammals suckle their young. The point about these deductive arguments,like mathematical ones,is that their assumptions or premises entail their conclusions.By "entail"we mean that should the premises be true then,as a matter of logic,the conclusion must also be true. In science,inferences from data to generalizations or to predictions typically do not entail their conclusions;they do not carry the logical inevitability of deduction.Say a doctor observes that all their patients suffering from colitis also suffer from anaemia. They might hypothesize that they go together,so that everyone who has colitis is also anaemic.Further observation that all of a large variety of colitis patients have anaemia would be regarded as evidence in favour of this hypothesis.But,however many such patients we observe,we have not ruled out the logical possibility of a colitis patient without anaemia.Similarly,overwhelming evidence in favour of the theory that the extinction of the dinosaurs was caused by a meteorite impact does not logically rule out all alternative hypotheses.(The evidence may rule out all sensible alternative hypotheses, for instance that the cause was volcanic eruption.But some explanations cannot be ruled out.For instance,one creationist view is that the fossil record was specially created by God as if there had been dinosaurs.One could imagine similar hypotheses relating to the evidence for meteorite impact.Perhaps one could hypothesize that the dinosaurs were executed by criminal extraterrestrials,who carefully covered their tracks.) These scientific,non-deductive arguments are often called inductive.We have to be a little careful here because the word "inductive"is used in at least two different ways.In its broadest sense it means just"non-deductive"and is thereby supposed to cover all the kinds of argument found in science (other than any deductive ones).So,the great historian and philosopher of science,Sir William Whewell spoke of the inductive sciences simply to contrast them with the deductive sciences of logic and the various branches of mathematics."Induction"has also been used to name a more specific kind of scientific argument,i.e.one where we argue from several particular cases to the truth of a generalization covering them.We have just seen the case of a doctor who took the existence of many anaemic colitis sufferers to be evidence for the claim that all colitis sufferers have anaemia;this was inductive reasoning in this second,more specific sense. The hypothesis that meteorite impact caused the extinction of the dinosaurs can be
All these differences between mathematics and the natural sciences characterize the distinction between deductive and non-deductive reasoning. Not only mathematical reasoning is deductive. For example, the following argument is deductive: All mammals suckle their young; otters are mammals; therefore otters suckle their young. The next is deductive too: Duck-billed platypuses do not suckle their young; platypuses are mammals; therefore not all mammals suckle their young. The point about these deductive arguments, like mathematical ones, is that their assumptions or premises entail their conclusions. By “entail” we mean that should the premises be true then, as a matter of logic, the conclusion must also be true. In science, inferences from data to generalizations or to predictions typically do not entail their conclusions; they do not carry the logical inevitability of deduction. Say a doctor observes that all their patients suffering from colitis also suffer from anaemia. They might hypothesize that they go together, so that everyone who has colitis is also anaemic. Further observation that all of a large variety of colitis patients have anaemia would be regarded as evidence in favour of this hypothesis. But, however many such patients we observe, we have not ruled out the logical possibility of a colitis patient without anaemia. Similarly, overwhelming evidence in favour of the theory that the extinction of the dinosaurs was caused by a meteorite impact does not logically rule out all alternative hypotheses. (The evidence may rule out all sensible alternative hypotheses, for instance that the cause was volcanic eruption. But some explanations cannot be ruled out. For instance, one creationist view is that the fossil record was specially created by God as if there had been dinosaurs. One could imagine similar hypotheses relating to the evidence for meteorite impact. Perhaps one could hypothesize that the dinosaurs were executed by criminal extraterrestrials, who carefully covered their tracks.) These scientific, non-deductive arguments are often called inductive. We have to be a little careful here because the word “inductive” is used in at least two different ways. In its broadest sense it means just “non-deductive” and is thereby supposed to cover all the kinds of argument found in science (other than any deductive ones). So, the great historian and philosopher of science, Sir William Whewell spoke of the inductive sciences simply to contrast them with the deductive sciences of logic and the various branches of mathematics. “Induction” has also been used to name a more specific kind of scientific argument, i.e. one where we argue from several particular cases to the truth of a generalization covering them. We have just seen the case of a doctor who took the existence of many anaemic colitis sufferers to be evidence for the claim that all colitis sufferers have anaemia; this was inductive reasoning in this second, more specific sense. The hypothesis that meteorite impact caused the extinction of the dinosaurs can be Philosophy of science 8