For two months now, as accusations of sexual misconduct have piled up against Harvey Weinstein, the disgraced mogul has responded over and over again: "Any allegations of nonconsensual sex are unequivocally denied." Consent is a concept central to law on sexual assault, and will likely be an issue in potential legal cases against Weinstein, who is under investigation by police in four cities, and others accused in the current so-called "reckoning." But the definition is a matter of intense debate: Is it a definite "yes," or the mere absence of "no"?