There is an argument that occasionally comes up when discussing communal policy. I call the argument the "if only one..." argument. The basic thrust of the argument is as follows: If only one life/soul is saved by implementing policy X, we should do so.
One of the latest examples comes from this Yeshiva World News article concerning teens and cell phones. One commenter said (bolding mine):
r’ webber is absolutely right as is the hanhala of bais shaindel but i ask all readers and comment posters if even one neshoma is lost due to texting or internet isn’t that reason enough for the small sacrafice of voice only phones for all of us and anyone saying that they know better is to blame for all future destruction caused by this epidemic
The fallacy of this argument is that it could be applied to almost anything. For example, perhaps we should outlaw the use of cars (except emergency vehicles). After all, if even one life can be saved, shouldn't that be reason enough?
The fact of the matter is that every activity that we engage in has a specific amount of risk. Every time a person gets into a car (or walks down the street, or plays baseball, or eats, etc.) there is a small possibility that the activity will cost them their life, God forbid. Yet we, as a society, determine that we're going to accept a certain number of fatalities for engaging in this activity. About 42,000 people die per year in car accidents. Shouldn't we invoke the doctrine of v'nishmartem m'od l'nafshoseichem and ban car driving (again, except for emergency vehicles)?
I don't know the number of people who die from alcohol poisoning on Purim, but shouldn't we ban it even if only one person could be saved?
Heck, perhaps we should prevent our kids from coming into contact with any other kids. After all, if even we can save one neshoma from coming into contact with a bad influence and going off the derech, shouldn't we accept that small sacrifice?
Of course, the above questions are ludicrous. The fact of the matter is that we, as a society, have determined that having the benefits of automobiles available to all of us is worth the 42,000 lives that it costs each year. We, as a society, have determined that the value of being able to drink on Purim is worth the possibility that some people may abuse the privlige and die from too much drink. We, as a society, determine that our kids having friends is worth the risk that one of them might turn out bad, even to the point where it might cost us some neshomos down the line.
Now, it should be pointed out that my argument has nothing to do with whether teens should be allowed to have cell phones or not. There are valid arguments for both sides. But the "if only one..." fallacy is not a valid argument -- and it turns up all too often in public policy decisions.