{"id":1058,"slug":"darby-karni-1973-credence-goods-framework","title":"Darby & Karni (J Law Econ 1973) — \"credence good\": quality consumers never discover even after consumption","kind":"reference","scope":"business","status":"current","audiences":["kevin","candid-team"],"topics":["psychology-aversion","credence-goods"],"reference_body":"**Claim:** Darby, M. R. & Karni, E. \"Free Competition and the Optimal Amount of Fraud.\" *Journal of Law and Economics*, Vol. 16, No. 1 (April 1973), pp. 67–88. Introduces the term **credence good**: a good whose quality \"consumers never discover [...] even after consumption\" because the consumer lacks the expertise to evaluate either the diagnosis or the treatment.\n\nSubsequent canonical extensions:\n\n- Emons, W. \"Credence Goods and Fraudulent Experts.\" *RAND Journal of Economics* 28(1): 107–119 (1997).\n- Emons, W. \"Credence Goods Monopolists.\" *International Journal of Industrial Organization* 19: 375–389 (2001).\n- Dulleck, U. & Kerschbamer, R. \"On Doctors, Mechanics, and Computer Specialists: The Economics of Credence Goods.\" *Journal of Economic Literature* 44(1): 5–42 (2006).\n- Wolinsky, A. on reputation in credence-good markets (RAND J Econ, 1995).\n- Chiu & Karni, work on credence-good reputation dynamics (2021).\n\n**Confidence:** Verified (primary academic literature).\n\n**Key finding from the literature:** Credence-good markets are systematically prone to **over-prescription, fraud, and information-asymmetry-driven mistrust**. The default rational stance for an uninformed buyer is skepticism. Reputational and referral mechanisms partially compensate — see Wolinsky 1995 — which is the theoretical basis for why peer-referred vendors close at far higher rates than cold-pitched ones.\n\n**For Candid:** Foundational. The category-level marketing aversion in GCs is **not irrational**; it is the predicted equilibrium behavior of a credence-good market with asymmetric information. The applied version is [[marketing-services-as-credence-good-for-gc]] and the strategic response is [[rule-concede-credence-good-problem-make-marketing-inspectable]].","rationale_body":null,"metadata":null,"links":{"outgoing":[{"slug":"research-brief-psychology-gc-marketing-aversion-may-2026","title":"Research brief: the psychology of marketing aversion among general contractor owners (May 2026 foundation)","kind":"reference","scope":"business","link_type":"relates-to"}],"incoming":[{"slug":"rule-concede-credence-good-problem-make-marketing-inspectable","title":"Rule: concede the credence-good problem; make marketing as inspectable as possible","kind":"rule","scope":"business","link_type":"depends-on"},{"slug":"marketing-services-as-credence-good-for-gc","title":"Marketing services are a near-paradigmatic credence good for a GC buyer","kind":"reference","scope":"business","link_type":"depends-on"}]},"created_at":"2026-05-24T23:24:06.304Z","updated_at":"2026-05-24T23:24:06.304Z"}