Lord Kelvin on quantitative knowledge

Tagged: Math / NotableAndQuotable / Obscurantism

Qualitative knowledge is real, but… quantitative knowledge is almost always better.

On the importance of being able to express your beliefs about the world in mathematical terms, a venerable quote from famous 19th century physicist William Thomson, 1st Baron Kelvin. He’s worth listening to, as he’s the inventor of large swaths of thermodynamics (and, to be fair, a few silly predictions like “there is nothing new to be discovered in physics” on the eve of the quantum mechanics & relativity revolution!):

Lord Kelvin

In physical science a first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about and express it in numbers you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.
— Thomson, W. (1891). Popular Lectures and Addresses, Vol. I, p. 80.

Written Sat 2020-Jul-18

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