Perfect is the enemy of good

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Perfect is the enemy of good is an aphorism which means insistence on perfection often prevents implementation of good improvements. The Pareto principle or 80–20 rule explains this numerically. For example, it commonly takes 20% of the full time to complete 80% of a task while to complete the last 20% of a task takes 80% of the effort.[1] Achieving absolute perfection may be impossible and so, as increasing effort results in diminishing returns, further activity becomes increasingly inefficient.


In the English-speaking world the aphorism is commonly attributed to Voltaire, who quoted an Italian proverb in his Questions sur l'Encyclopédie [fr] in 1770: "Il meglio è l'inimico del bene".[2] It subsequently appeared in his moral poem, La Bégueule, which starts:[3]

Dans ses écrits, un sage Italien
Dit que le mieux est l'ennemi du bien.

(In his writings, a wise Italian
says that the better is the enemy of the good.)

Previously, around 1726, in his Pensées, Montesquieu wrote "Le mieux est le mortel ennemi du bien" (The better is the mortal enemy of the good).[4]


Aristotle and other classical philosophers propounded the principle of the golden mean which counsels against extremism in general.[5]

Its sense in English literature can be traced back to Shakespeare.[6] In his tragedy King Lear (1606), the Duke of Albany warns of "striving to better, oft we mar what's well" and in Sonnet 103:

Were it not sinful then, striving to mend,
To mar the subject that before was well?


The 1893 Dictionary of Quotations from Ancient and Modern, English and Foreign Sources lists a similar proverb, which it claims is of Chinese provenance: "Better a diamond with a flaw than a pebble without one."

More recent applications include Robert Watson-Watt propounding a "cult of the imperfect", which he stated as "Give them the third best to go on with; the second best comes too late, the best never comes";[7] economist George Stigler's assertion that "If you never miss a plane, you're spending too much time at the airport";[8][9] and, in the field of computer program optimization, Donald Knuth's statement that "Premature optimization is the root of all evil".[10]

See also[edit]


  1. ^ E. Gandevia; S. Breakspear (2009), Equip, Talent Generation, p. 30, ISBN 978-0980679304
  2. ^ Voltaire (1770). Questions sur l'Encyclopédie, par des Amateurs. Vol. 2. Geneva, Switzerland: (publisher not named). p. 250.
  3. ^ Georg Wilhelm Friedrich Hegel; Allen W. Wood; Hugh Barr Nisbet (1991), Elements of the Philosophy of Right, Cambridge University Press, p. 447, ISBN 978-0521348881
  4. ^ Robert Shackleton (1988), Essays on Montesquieu and on the Enlightenment, Voltaire Foundation at the Taylor Institution, ISBN 978-0-7294-0354-2
  5. ^ Tal Ben-Shahar (2009), The Pursuit of Perfect, McGraw Hill Professional, p. 113, ISBN 978-0-07-160882-4
  6. ^ Robert Allen (2008), Allen's Dictionary of English Phrases, Penguin UK, pp. 242–243, ISBN 978-0140515114
  7. ^ L Brown (1999), Technical and Military Imperatives: A Radar History of World War 2, p. 64, ISBN 9781420050660
  8. ^ Natasha Geiling (23 June 2014), "If You've Never Missed a Flight, You're Probably Wasting Your Time", Smithsonian
  9. ^ Steven E. Landsburg (2008), More Sex Is Safer Sex: The Unconventional Wisdom of Economics, Simon and Schuster, p. 224, ISBN 9781416532224
  10. ^ Donald Knuth (2015), Rubin H. Landau; Manuel J. Páez; Cristian C. Bordeianu (eds.), Computational Physics, Wiley, ISBN 9783527413157

Further reading[edit]

  • Eric Johns (October 1988), "Perfect is the Enemy of Good Enough", U.S. Naval Institute Proceedings: 37
  • Robert Watson-Watt (1957), "The Cult of the Imperfect", Three Steps to Victory, Odhams, pp. 74–77