David Dequech (2021) Journal of Post Keynesian Economics, Online first Abstract. The role of conventions in Keynes’s theory has been controversial. When dealing with investment and production decisions, Keynes referred to a projective rule that is his main example of convention. In addition, conventions appear in the practical techniques that Keynes attributed to agents concerned with the accumulation of wealth. Two important points have been neglected in existing interpretations. Firs...