This paper examines, in the textual production of the so-called Activity Theory (from Charles Goodwin, Yrjö Engeström, Reijo Miettinen e Michael Cole), the theoretical and methodological dispute between marxism and postmodern trends, concerning the notions of activity, language and labour. The paper analyses polyphonic and discourse-ideological effects in the mentioned production, pointing out an attempt to sweep marxism away from Vigotski, Luria e Leontev. Also, the paper discusses the consequences to language and labour studies.