We show that the conventionally defined partonic cross section for the
production of isolated prompt photons is not an infrared safe quantity. We work
out the case of e+e−→γ+X in detail, and we discuss implications
for hadron reactions such as ppˉ→γ+X.Comment: 8 pages, latex2e, 2 figures, uses Moriond.sty; Invited paper
presented by E. L. Berger at the XXXIInd Rencontres de Moriond, QCD and High
Energy Hadronic Interactions, Les Arcs, Savoie, France, March 22 - 29, 199