Thursday, October 26, 2006

Descriptive vs Explanatory Laws

[William Robin Thompson] was most concerned that entomologists should understand that mathematical "laws" merely expressed natural processes, they did not govern them. The distinction he made between a law as description versus law as explanation was similar to that made by Karl Pearson in The Grammer of Science.But where Pearson regarded such laws as having predictive value in physics, Thompson denied it could ever do that in biology. This was not just because mathematics were too simple in comparison with nature. Mathematics no matter how intricate, could never help biologists to understand causal relations, because natural events were made up of unique causes which were necessarily unpredictable:
"The tremendous multiplicity of factors acting on the real world has not merely the complexity of an elaborate mathematical equation, which is theoretically but not practically manageable; but implies a genuine unpredictability because the actual combination of factors has never been observed to operate and until it has, we cannot really be sure what its effect will be. Much less can we see this effects in its causes."



pg 140
Modelling Nature

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