Programming Terminology – Why Are Actual Parameters Called ‘Arguments’?

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Where does the word "argument" (in the programming sense) come from?
i.e. Why are actual parameters called "arguments"?

The meanings don't seem related, and I haven't found any explanation of it anywhere.

Note on the terminology:

  • "Formal" parameters (also known simply as "parameters") are the "placeholder" names (say, x) — the declared parameters of a function.

  • "Actual" parameters (also known as "arguments") are the actual values which are passed to a function (say, 5), hence I used this term above to prevent any confusion.

Best Answer

The term was adopted by computer scientists when they applied mathematical reasoning to programming in the mid 20th century.

The word argument has the general sense of something from which another thing may be deduced. It comes ‘from the L. arguere “make clear, make known, prove, declare, demonstrate,” from PIE *argu-yo-, from root *arg- “to shine, be white, bright, clear” ’, which root is also preserved in the words argent (“silvery white”) and Argentina (“[river] of silver”).¹

Its use in English to mean a “mathematical quantity from which another … quantity may be deduced, or on which its calculation depends” is attested as early as 1386:

 Argument (ā·ɹgiuměnt). [a. F. argument (13th c.), ad. L. argūment-um, f. arguěre (or refashioning, after this, of OF. arguement, f. arguer): see ARGUE. For use of the L. form, see 3 c.]
 2. Astr. and Math. The angle, arc, or other mathematical quantity, from which another required quantity may deduced, or on which its calculation depends.
 c 1386 CHAUCER Frankl. T. 549 Hise othere geeris, As been his centris and hise Argumentz.
 c 1391 — Astrol. xliv. 54 To knowe the mene mote and the argumentis of any planete.
 1796 HUTTON Math. Dict. I. 141/2 Annual argument of the moon’s apogee . . is the distance of the sun’s place from the place of the moon’s apogee.
 1879 THOMPSON & TAIT Nat. Phil. I. 1. § 54 An arc of the circle referred to . . is the Argument of the harmonic motion.²

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