The fatal moment
When Diane Schuler parked at a pull-over area on the New York State Thruway at the east side of the Tappan Zee Bridge, and told her brother Warren Hance on her cell phone that she was disoriented and having trouble seeing, and he told her to stay there and he would come for her, that was her last act as a human being in this world.
First, she put down the cell phone and left it at the parking area where she had been using it, cutting herself off, both pragmatically and symbolically, from further communication with anyone in the world outside her van.
Second, she got back in the van and commenced driving again, despite the fact that she had just said she was disoriented and having trouble seeing, and her brother had told her to stay where she was until he came to her.
When she did those two things, she crossed a line, away from humanity, away from life—becoming an enemy of humanity and life. What made her do it, and whether she was conscious of what she was doing or had been transformed by some unknown force into a robot or zombie, we don’t know and may never know.
Many people believe that alcohol, or alcohol plus marijuana, can account for her behavior. Maybe they’re right, though I’m doubtful.
But in a way it doesn’t matter what factors were driving her, whether alcohol or something else, and it doesn’t matter how conscious she was. Whether she acted in total unconsciousness (like a zombie being pulled by strings), or in partial consciousness (having only an extreme focus on the “tunnel” in front of her and nothing else), or in full consciousness (evilly intending her own death and that of her children and nieces, as Josh F. argues), or in an extreme drunken state in which she was totally heedless of what she was doing, what she did is what matters. And when she put down that cell phone and got into that van, though she still had a half-hour of life ahead of her, her existence as a human being was effectively over.