In the case above, the river would simply develop a fourth channel. What is perhaps more surprising, then, is that safety and health authorities have traditionally told people what they should or should not do to avoid injury or lifestyle-dependent disease, without offering them motivation to reduce risk, without offering them a reason to live longer. And what may be more surprising still is that the wisdom and effectiveness of this prevention practice is so rarely questioned. It is obvious that a sure way to reduce the accident rate on a particular road to zero is to simply close that road to all traffic. It is almost as obvious that road users will move to other roads and that the accidents will migrate with them to other locations.
Road closure is no effective remedy.
To believe so is to fall victim to the delta fallacy. The chapters following call the traditional prevention practice into question. Specifically, it is argued that the traditional reliance on enforcement of laws, on informing the public of certain dangers, and on engineering the physical features of the human-made environment is not very productive towards greater health and safety insofar as these are dependent on human conduct. An effort is made to explain why this is so. At first, this may appear to be a pessimistic exercise, but nothing could be further from the truth.