Q: I know that both of these sentences are correct: “Pi is transcendental” and “Pi is a transcendental number.” But which would you prefer?
A: The word “transcendental,” which English adopted from medieval Latin in the 17th century, has a lot of meanings, including transcendent, exalted, supernatural, and abstract.
In Aristotelian philosophy, it refers to extending beyond the bounds of any single category. In Kantian philosophy, it applies to something not derived from experience.
It can also refer to Transcendentalism, the 19th-century literary, philosophical, cultural, and religious movement in New England.
And in the mathematical sense, the one you’re asking about, “transcendental” is defined in the Oxford English Dictionary this way:
“Not capable of being produced by (a finite number of) the ordinary algebraical operations of addition, multiplication, involution, or their inverse operations; expressible in terms of the variable only in the form of an infinite series.”
Considering all those meanings (mathematical, philosophical, cultural, etc.), we’d be sure to keep our audience in mind when using the word “transcendental.”
In an obvious numerical context (a math text, for example), either of your examples (“Pi is transcendental” or “Pi is a transcendental number”) would be OK.
In any other context, however, we’d recommend going with the second example, plus adding a definition of “transcendental” in the mathematical sense.
And if your head is spinning from that OED definition, you could consider “transcendental meditation,” the method of relaxation and meditation based on the teachings of Maharishi Mahesh Yogi.
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