Introduction:the nature of science 3 can be verified,(e)In particular,if these testable claims are found to be refuted by experience,then this should count as powerful evidence against the theory,which may amount to showing the theory to be false.Our belief in the theory should be proportional to the strength of the evidence in its favour (which means considering it in relation to its rivals),(d)Even if the evidence is very favourable,experience shows that sophisticated well-confirmed theories can be overturned by falsifying evidence found later or challenged by new competing theories that themselves are supported by the evidence in the way that the original theory is not.A scientific attitude requires being open to this possibility. Let us look at some examples.The creationist says that the Earth's geological features are explained in terms of catastrophic events,primarily a large-scale flood.By contrast, standard geology explains them in terms of forces that work over extended periods of time-erosion,glaciation,plate tectonics.The latter can all be understood as phenomena that obey the laws of physics.For instance,tidal motion is a result of the Moon's gravitational pull,and so is a manifestation of the law of gravity.Even if a massive flood could explain the Earth's geology,why did the flood occur in the first place?While disastrous floods do still happen today,they are restricted in scope and can to some extent be explained by reference to local weather conditions such as hurricanes.But a global flood is a different matter.What sort of weather conditions could bring about such a calamity?If the whole Earth was covered in water,where did it all come from?And where did it go to thereafter?No laws or law-governed phenomena are invoked-or could be-to answer such questions.The reason why is clear.A flood,Noah's,is referred to in the book of Genesis.This flood was the work of divine intervention.While God's actions may indeed be the correct explanation of an event,such an explanation fails to be scientific by Judge Overton's criteria.God's will is not subject to natural law.And for precisely that reason this hypothesis is not testable either.God does not submit to experimentation. Of course all explanations end somewhere,even orthodox ones.The difference here is that the orthodox scientist seeks to extend the chain of explanations as far as possible and is limited only by ignorance,while the creationist is happy to terminate the chain of explanations much earlier,in accordance with biblical constraints,and at that point to use supernatural explanations. Another reason creationists have for adopting catastrophism is that they are committed to a young Earth-six to ten thousand years old-too young for the long-term effects of traditional geological processes.The nineteenth century physicist Lord Kelvin (whose name was given to the scale of temperature)made careful calculations concerning the rate of cooling of the Earth and Sun.These suggest that the solar system could not have been around long enough for life to have evolved.His arguments are still quoted by creationists.Kelvin's calculations were quite right-if one assumes no heat source in the Earth and that the Sun's energy comes from combustion.In both cases there are energy sources he ignored,viz.nuclear processes,fusion in the Sun,and radioactive decay in the Earth.Lord Kelvin can be forgiven for not knowing about something discovered only after he made his calculations;a contemporary writer cannot.Again the best explanation of the creationists'stance is not the evidence and arguments that they present,but a prior commitment to biblical historiography (from which the date of Adam's creation and so the creation of everything can be calculated).can be verified, (e) In particular, if these testable claims are found to be refuted by experience, then this should count as powerful evidence against the theory, which may amount to showing the theory to be false. Our belief in the theory should be proportional to the strength of the evidence in its favour (which means considering it in relation to its rivals), (d) Even if the evidence is very favourable, experience shows that sophisticated well-confirmed theories can be overturned by falsifying evidence found later or challenged by new competing theories that themselves are supported by the evidence in the way that the original theory is not. A scientific attitude requires being open to this possibility. Let us look at some examples. The creationist says that the Earth’s geological features are explained in terms of catastrophic events, primarily a large-scale flood. By contrast, standard geology explains them in terms of forces that work over extended periods of time—erosion, glaciation, plate tectonics. The latter can all be understood as phenomena that obey the laws of physics. For instance, tidal motion is a result of the Moon’s gravitational pull, and so is a manifestation of the law of gravity. Even if a massive flood could explain the Earth’s geology, why did the flood occur in the first place? While disastrous floods do still happen today, they are restricted in scope and can to some extent be explained by reference to local weather conditions such as hurricanes. But a global flood is a different matter. What sort of weather conditions could bring about such a calamity? If the whole Earth was covered in water, where did it all come from? And where did it go to thereafter? No laws or law-governed phenomena are invoked—or could be—to answer such questions. The reason why is clear. A flood, Noah’s, is referred to in the book of Genesis. This flood was the work of divine intervention. While God’s actions may indeed be the correct explanation of an event, such an explanation fails to be scientific by Judge Overton’s criteria. God’s will is not subject to natural law. And for precisely that reason this hypothesis is not testable either. God does not submit to experimentation. Of course all explanations end somewhere, even orthodox ones. The difference here is that the orthodox scientist seeks to extend the chain of explanations as far as possible and is limited only by ignorance, while the creationist is happy to terminate the chain of explanations much earlier, in accordance with biblical constraints, and at that point to use supernatural explanations. Another reason creationists have for adopting catastrophism is that they are committed to a young Earth—six to ten thousand years old—too young for the long-term effects of traditional geological processes. The nineteenth century physicist Lord Kelvin (whose name was given to the scale of temperature) made careful calculations concerning the rate of cooling of the Earth and Sun. These suggest that the solar system could not have been around long enough for life to have evolved. His arguments are still quoted by creationists. Kelvin’s calculations were quite right—if one assumes no heat source in the Earth and that the Sun’s energy comes from combustion. In both cases there are energy sources he ignored, viz. nuclear processes, fusion in the Sun, and radioactive decay in the Earth. Lord Kelvin can be forgiven for not knowing about something discovered only after he made his calculations; a contemporary writer cannot. Again the best explanation of the creationists’ stance is not the evidence and arguments that they present, but a prior commitment to biblical historiography (from which the date of Adam’s creation and so the creation of everything can be calculated). Introduction: the nature of science 3