 Holders of expert knowledge are supposed to be reliable in the exercise of that knowledge; they are professionals, and part of their professionalism is to ply their trade competently regardless of the weight of passion or the blandishments of pleasure. So the techne analogy might be construed to imply the impossibility of acrasia. Socrates’ argument for this in the  Protagoras,  however, is based on his demonstration that the popular explanation for weak-willed behavior (that knowledge is overcome by pleasure) is incoherent. Socrates is not denying that people do wrong under the influence of passion or desire for pleasure; he is rejecting the usual explanation for this, and denying that it occurs in the case of those who have the relevant knowledge. Plainly, the doctrine presupposes a stringent criterion for knowledge, at least as demanding as the test for techne.