Monday, December 15, 2008

Philosophy of Science: A Very Short Introduction

Philosophy of Science: A Very Short Introduction #67
Samir Okasha
Oxford ; New York : Oxford University Press, ©2002
144 p. Includes bibliographical references and index

    It has been a particular pleasure to read this Very Short Introduction, as many of the philosophers mentioned in it I haven't thought about for quite some time. So to remake their acquaintance has been fun.
    This is not so much a book about scientific investigation as it is an open question about how we know what we know from those investigations.  So I read with delight how David Hume (who's alcohol consumption is apparently legendary, allowing him to out-consume  other philosophers) says simply that we cannot rationally justify inductive reasoning, and although we use inductive reasoning regularly (the sun's come up every day up until now, so it should come up tomorrow), that doesn't make it right.  The idea that arguing in favour of inductive reasoning is, in itself, inductive reasoning and quickly develops circularity, is exciting to me, reminding me that big questions are still out there to be debated.
    Samir Okasha leads us through these Big Questions with assurance ind intelligence. His goal is not to argue in favour of any of them, but to explore the history of ideas and the criticisms of those ideas.  His illustrations are generally deceptively simple and clear, illuminating the philosophical problems under discussion with grace and ease.
    As an example, he presents the problem of  what exactly is scientific explanation? And what does it mean to say that a problem can be explained by science?  Okasha begins with a philosopher I hadn't previously encountered; Carl Hempel. After a brief recap of Hempel's “covering law” model of explanation,  Okasha develops a schematic of Hempel's model:

General laws
Particular facts
Phenomenon to be explained

To quote  Okasha, “...Hempel's model is called the covering law model of explanation. For according to the model, the essence of explanation is to show that the phenomenon to be explained is 'covered' by some general law of nature.”  So far, so good. But there are critics of Hempel who suggest that his covering law model allows in things that should be excluded. As an example,  Okasha writes out a thought experiment:
    Suppose you are lying on the beach on a sunny day, and you notice that a flagpole is casting a shadow of 20 metres across the sand. So why, someone asks, is the shadow 20 metres long?
    The answer is fairly straightforward: The elevation of the sun in 37°, and light travels in a straight line (straight enough for the purposes of this discussion, anyway). The flagpole is 15 metres high. The trig calculation indicates that the shadow will be 20 metres long.
    So far so good. General laws= light travels in straight lines and trigonometric laws. Particular facts= angle of elevation of the sun and height of the flagpole. Phenomenon to be explained=the 20 metre long shadow.
    But what if we change the explanandum (the phenomenon being explained)? Let's change it to the height of the flagpole.  In our case above, this simply swaps the length of the shadow into the “particular facts” group and the height of the flagpole into the “phenomenon being explained” group.  But something odd happens—the explanation doesn't really fit. Mathematically it is true. But as an explanation as to why the flagpole is 15 metres high, well, it falls down. The flagpole is what it is for completely different reasons: the contract to install the flagpole specified the height, that was the only flagpole available, whatever. So while the “answer” conforms to Hempel's model, it allows something to stand as a scientific explanation that is clearly incorrect except mathematically.

    So we have questions raised about whether explanation and prediction are simply two sides of the same coin, or radically different concepts.  And  Okasha opens these questions with a simple example that allows us to see the underlying philosophical questions.   Okasha does this again and again, asking whether a theory is really to describe hidden facts (ie.  gases really do contain molecules in motion) or  are they just a way to predict observations? And what is the difference? Or do we trust scientific paradigms or treat them with a certain amount of scepticism? After all, they do change, and they do change radically (think of the change from the Ptolemaic to Copernican paradigm).
    Reading  Philosophy of Science gave me the feeling of being at play in the realm of pure thought—a lovely place to be, and one I haven't visited all that recently.  Quite the delightful Very Short Introduction.

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