"One man's constant is another man's variable"
About this Quote
Programmers love to pretend the world is tidy: nail down a few constants, build a system on top, go home. Perlis punctures that fantasy with a single line that reads like a math truism and lands like a cultural critique. "One man's constant is another man's variable" is less about symbols than about authority: who gets to declare something fixed, and who has to live with it changing under their feet.
In computing, "constant" and "variable" are technical terms, but Perlis uses them as a portable metaphor for human institutions. In one codebase, a value is hard-coded because it feels stable; in another, the same value becomes a parameter because experience has taught them it will drift. That gap is where engineering judgment lives: the boundary between what you assume and what you instrument. Perlis is warning that most bugs, and a lot of organizational pain, come from mistaking contingent decisions for natural laws.
The subtext is gently cynical about expertise. What looks like rigor can be habit. A "constant" can be a political choice disguised as necessity; a "variable" can be an admission of humility disguised as flexibility. Perlis, writing in the era when software was professionalizing and systems were scaling, is pointing at a perennial failure mode: we freeze yesterday's assumptions into today's infrastructure, then act surprised when reality treats them as optional.
It works because it flatters and indicts at once: you're smart enough to appreciate the pun, and implicated enough to reconsider what you've hard-coded in your own thinking.
In computing, "constant" and "variable" are technical terms, but Perlis uses them as a portable metaphor for human institutions. In one codebase, a value is hard-coded because it feels stable; in another, the same value becomes a parameter because experience has taught them it will drift. That gap is where engineering judgment lives: the boundary between what you assume and what you instrument. Perlis is warning that most bugs, and a lot of organizational pain, come from mistaking contingent decisions for natural laws.
The subtext is gently cynical about expertise. What looks like rigor can be habit. A "constant" can be a political choice disguised as necessity; a "variable" can be an admission of humility disguised as flexibility. Perlis, writing in the era when software was professionalizing and systems were scaling, is pointing at a perennial failure mode: we freeze yesterday's assumptions into today's infrastructure, then act surprised when reality treats them as optional.
It works because it flatters and indicts at once: you're smart enough to appreciate the pun, and implicated enough to reconsider what you've hard-coded in your own thinking.
Quote Details
| Topic | Truth |
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