A reader writes,
The other day I heard a radio commentator constantly using the phrase “in that calculus”, something I’d never heard before. [The] commentator was using it in a political context, pretty much as a fancy way of saying “in that situation”; I’d be grateful if you could look into it and cover it some time!
Calculus is one of those words like parameter and paradigm that have been yanked from their habitual scientific contexts into the general vocabulary by non-scientists to make their utterances sound more profound.
In the context of mathematics, the word calculus is usually preceded by differential or integral:
integral calculus: a branch of mathematics concerned with the theory and applications (as in the determination of lengths, areas, and volumes and in the solution of differential equations) of integrals and integration.
differential calculus: a branch of mathematics concerned chiefly with the study of the rate of change of functions with respect to their variables especially through the use of derivatives and differentials.
Calculus is the diminutive of Latin calx, “stone.” A calculus was a little stone or pebble. The plural, calculi gives us the word calculation because pebbles were used for counting. Calculi were also used as game pieces and for voting.
In the context of medicine, calculus is a hard deposit that builds up in the body to produce kidney stones, plaque, and such.
The word calculus is now to be found in a variety of contexts:
Competition along routes is just one variable in that calculus. (The context is a discussion of the process of airline pricing.)
They are casting Ellsworth as an unwilling enabler who will further an agenda even though he might not fully support it. And, in that calculus, his vote for Speaker of the House comes first and foremost.
No medical intervention is 100% safe. However vaccines are remarkably safe…It is risk versus benefit and in that calculus vaccines win.
J. C. Watts Endorsing Newt Gingrich is Awful Political Calculus
In New Calculus on Smoking, It’s Health Gained vs. Pleasure Lost
The political calculus on immigration reform changes day by day, but the moral calculus has not.
It seems to me that in each of these examples, situation, calculation, or thinking would serve the context.