Eric L. Titus argues that 1 Corinthians is an interpolation to the text of First Corinthians.
Eric L. Titus, "Did Paul Write 1 Corinthians 13?", Journal of Bible and Religion 27, no. 4 (October 1959): 299-302
In popular thought the thirteenth chapter of I Corinthians is normative Pauline teaching; for the average Christian this is Paul. I Corinthians 13 stands out in his mind in the same way as does the 23rd Psalm or the Matthean version of the Lord's Prayer. The reason for this are not at all obscure. For one thing, the passage thrusts itself out from the Corinthian letter as if to invite special attention. Secondly, the chapter forms a neat, self-contained literary unit, dealing concisely with the theme of love. Thirdly, the theme meets people on a level which they can understand (or think they can understand) while the more complicated theological constructs of Paul do not. And finally, the theme of love is expressed in noble literary form, making its retention in the memory easy.
These factors which make the passage to conspicuously different from the mass of Pauline material, suggest the possibility that the chapter is an interpolation. This paper is an examination of this possibility.