 Drawing on his account of probable impressions, Carneades defended two views about assent. He sometimes argued that the wise person will always withhold assent, but will be able to act and inquire by following or using probable impressions in a way that does not amount to assent, and so does not involve holding opinions about anything (Acad. 2.59, 99, 108). On other occasions, he maintained that the wise person will assent to what is probable and so form opinions, but with the proviso that he may be wrong (Acad. 2.59, 67, 78, 112). In this way he gave his interlocutors a choice between two alternatives to Stoic orthodoxy, each of which describes a way of life without the certainty furnished by cognitive impressions. Either one lives entirely without opinions, while following probable impressions without assenting to them or one lives with opinions, but opinions that are held in a self-consciously tentative spirit and subject to revision in the light of new evidence.