Overview

Semantics, rhetoric, logic and assumptions play a large role in science but are usually relegated to specialized books and courses on philosophy and paradigms. Conventional wisdom is often the controlling factor in picking and solving problems. This chapter is a detour into issues that may be holding up efforts to develop a theory of the Earth, one that is as paradox free as possible.

A large part of petrology, geochemistry and geophysics is about sampling the Earth. Sampling theory is a branch of statistics. If the mantle is blobby on a kilometer scale, then individual rocks will exhibit large scatter – or variance – but the mean of a large number of samples will eventually settle down to the appropriate mean for the mantle; the same mean will be achieved in one fell swoop by a large volcano sampling a large volume of the same mantle. If the outputs of many large volcanoes are plotted on a histogram, the spread will be much smaller than from the rock samples, even though the same mantle is being sampled.