"What would it mean to take intelligent design seriously at the medical school level? Its proponents tell us that gaps in our knowledge of how living organisms evolved vitiate the theory of evolution. Might we conclude, then, that the cancer cell and its evolution are so complex that a creative designer must be the cause of cancer? But if the designer created cancer, is it against the hidden hand's will to find a cure for cancer? Is it in accord with the plan of the intelligent designer to receive a treatment for cancer? After all, a Jehovah's Witness would rather die than receive a blood transfusion. Yet today more than ever, the profession needs physicians who can channel scientific discoveries to the sick. What effect will pseudoscience-by-fiat have on medical progress?"
Is it not painfully obvious where the logical jump occurs? Let's say that a creative designer is in some way the only explanation of cancer. Does this necessitate in any way the purpose (and thusly direction) of that hand? Of course not. But Dr Schwartz proceeds to assume that it follows naturally.
A similar disconnect occurs in free will/predestination arguments. Often, the discussion hinges on the idea that if I don't have free will (I'll leave this until later to be defined), then it doesn't matter what I do. This doesn't fit, though, as it assumes that you yourself know what it is you are going (supposed) to do.
Each of these arguments attempts to examine these subjects by noting that the directionality thought to be associated with ID or predestination can be discredited by assuming an endpoint (or laterpoint) that is in no way necessary. People may use this method of understanding every day. It just doesn't make it right (particularly not in such an excellent weekly as is NEJM).