A workman for hire promises the skill of his art; he who receives payment for his art must deliver workmanlike performance.

Explanation

Every hired craftsman impliedly warrants competence — payment for professional services carries with it the obligation of professional quality.

Where this applies

• I hired a professional and they did terrible work — they owe me competent performance.
• Every hired craftsman impliedly warrants they're competent at their trade.
• If you accept payment for your skill, you must deliver workmanlike quality.

See also

• 12.12.1 Commerce ought to be common, and not to be converted into a monopoly and the private gain of a few.
• 12.12.4 Goods are worth as much as they can be sold for.