Philosophy of Science 4 Questions on Copernicus and Gallileo Summary

December 2010 - Second Year - Philosophy of science : 4 questions about Copernicus and Galileo (600 words)

From Osiander's Foreward to De Revolutionibus, find at least two arguments for instrumentalism. Support your answer with quotations.

In Osiander's foreward, he contrasted the attitude of philosophers, as seekers of truth, to scientists, as seekers of theories to correctly compute and predict phenomena. The method of the scientist is to seek the simplest explanation to explain the phenomena - "If the causes are devised by the imagination... merely to provide a reliable basis for computation... the astronomer will take as his first choice the hypothesis which is easiest to grasp" - so readers should not be concerned with the way Copernicus' findings challenges their religious beliefs and convictions of truth about the universe. It is an instrumentalist argument because it posits that scientists cannot know the truth and that this should not worry us, the scientists role is merely to advance plausible explanations, which can be improved upon or replaced by subsequent explanations that better fit the data.

Furthermore, Osiander  tells the reader: "These hypotheses need not be true nor even probable... If they provide a calculus consistent with the observations, that alone is enough." He is further reinforcing that the reader should not be concerned by Copernicus' theories, merely their instrumental value in explaining the path of the planets.

 Using arguments and examples from Copernicus' Preface to De Revolutionibus, explain the difference between a simple theory, a complex theory, and a coherent theory. Is a coherent theory necessarily simple?

 Simplicity and complexity are relative terms, so a theory we might consider complex compared to another could appear simple compared to yet another theory. Furthermore, a single theory might be simple in some respects, yet complex in others. So the issues we are really concerned with in this question is whether we should favour simpler theories over more complex ones, and whether coherence necessitates simplicity.

 There are two important ideas to consider. The first is a rough interpretation of Occam's razor, which is when comparing multiple theories that explain a phenomena, the theory which introduces the lesser amount of independent assumptions is the theory most likely to be correct (or to be more useful, at least). We should favour simpler theories over more complex ones but only when both theories create correct predictions. Secondly, we should seek explanatory theories that are as simple as possible but no simpler. The 'no simpler' part of this answer is critical. Even if a theory appears complex, we cannot remove components of it merely to make it simpler.  The coherence of the theory - it must make sense, create correct predictions, and not introduce contradictions - cannot be compromised for the sake of simplicity, and so sometimes a coherent theory will not seem simple at all.

In the preface to De Revolutionibus, Copernicus explained he was compelled to research the motion of the planets and the sun because the existing explanations were contrastingly simple yet incoherent or coherent yet complex- those using homocentrics producing calculations not corresponding to empirical observation, and those using eccentrics seeming to have resorted to ad hoc variations to their theories to produce correct results.

 Describe an instance where Galileo believed a theory that appeared to be contradicted by some observational evidence. Was he justified in doing so (i.e. did he have good theoretical arguments or observational evidence)?
Copernicus' theory that the earth and other planets revolved around the sun was contradicted by visual observation of Mars and Venus from Earth, by the naked eye. The calculations derived from his theory suggested that the visible size and brightness of both planets would vary considerably during their orbit,  and these variations were not confirmed by observation.

When any empirical observation produces results that do not confirm to a theory, we might think that automatically proves our theory incorrect. However, it may simply be the case that our theory is missing some detail which would explain the difference in observation. Furthermore, there may be factors influencing our method of observation, or interpretation of what is being observed, that mislead us. So we should not obviously disregard a theory backed by comprehensive supporting evidence, merely because of some exceptional observations.

In Galileo's case, hindsight certainly suggests he was justified to believe Copernicus' theory, but what can we say philosophically about his persistence with it? Galileo was able to argue against the empirical contradictions by improving the method of observation with the telescope. Using the telescope and pursuing a mathematical account of how bodies of different size would appear from a distance, Galileo was able to garner new observational data to support the theory. However, if we apply Peter Gallison's criteria to validate observational processes of directness and stability, we may question whether Galileo's telescoping findings had the stability to support the theory. It is clear at least that Galileo did seek both theoretical (mathematical account) and observational (via telescope) evidence to support Copernicus' theory.

 Explain Galileo's general solution to the problem of the apparent incompatibility of science and religion in his 'Letter to Christina'.
 Galileo's general solution the problem of an appearance of incompatibility of science and religion in his 'Letter to Christina' involves suggesting reasons why the literal interpretation of the bible may include counterfactuals as well as establishing a logical case that God would not have provided sensory perception and reason for diagnosis of scientific truth if he did not wish them to be used.

 Firstly, Galileo suggests the bible was written to be understood by the common people. The simplest and most accessible representation of information was therefore necessary, so that those with little education or sophistication could understand it and accept it. For this reason, more sophisticated individuals need to accommodate for this bias in the reading of religious texts, to look deeper than face value to interpret the true meaning.

Secondly, as a believer in God, Galileo credited God for imparting him with the sensory perception to make empirical observation, and the reasoning capacity to conduct rational inquiry. As god has provided these capacities, he must wish for human beings to use them in pursuit of scientific truth, so to deny that process is illogical.