Volume 21, Issue 2 April 2025

Can Supply Shocks Be Inflationary with a Flat Phillips Curve?

Abstract

Not in standard models. With conventional pricing frictions, imposing a flat Phillips curve also imposes a price level that is rigid with respect to supply shocks. In the New Keynesian model, price markup shocks need to be several orders of magnitude bigger than other shocks in order to fit the data, leading to unreasonable assessments of the magnitude of the increase in costs during inflationary episodes. To account for the facts, we propose a strategic microfoundation of shockdependent price stickiness: prices are sticky with respect to demand shocks but flexible with respect to supply shocks. This friction is demand intrinsic, in line with narrative accounts for the imperfect adjustment of prices. Firms can credibly justify a price increase due to a rise in costs, whereas it is harder to do so when demand increases. Supply shocks, including productivity shocks, lead to a flexible price allocation, where inflation rises rapidly and output falls. An output gap ensues only if monetary policy is tightened.

Authors

  • Jean-Paul L’Huillier
  • Gregory Phelan

JEL codes

  • E31
  • E52
  • E58

Other papers in this issue

Thiago R T Ferreira and Nils Gornemann and Julio L Ortiz

Margherita Bottero and Stefano Schiaffi

Julien Bengui and Lu Han and Gaelan MacKenzie

Wolfgang Lechthaler and Mewael F Tesfaselassie

Richard K Crump and Stefano Eusepi and Domenico Giannone and Eric Qian and Argia Sbordone