Question: Is it morally correct for Israel to free dangerous terrorists in order to secure the release of a single soldier?
Answer: The debate at the core of the hostage exchange issue is often an emotional to-and-fro. Jewish Law presents the matter in an authoritative context: Is one obligated or even allowed to place oneself in danger to save another's life. On an individual level one may put himself in harm's way, but can an entire country willingly assume that responsibility when the lives of an entire population are at stake?
Assuming that the terrorists are not rehabilitated by their time spent in prison and upon release will return to their evil ways with even more vengeance placing millions in danger, one would have to carefully weigh up whether it is actually "worth the risk" to barter a single soldier for hundreds of killers.
Those who advocate the release of Gilad Shalit on halachik grounds argue that certainty outweighs potentiality. This means that the premise of the above question- that many innocent people will die- is misleading. The threat to the soldier's life is immediate and certain, whereas the threat to the population is only potential and not immediate.
The counter argument is that while certainty may outweigh potentiality, it does not necessarily outweigh probability. It is no secret that these terrorists openly plan to murder civilians upon release, the life threat is so clear that it can hardly be called "potential", and is more likely to be classified as "probable" danger. It would be synonymous to a case where 10 people are standing on track A and 1 person on track B with an unstoppable train heading on track A, in which case it would be morally acceptable to use the switcher to track B to save the many innocent people. In this light one would have to say that the concern for public safety takes precedence over a single life.
May G-d bless us that very soon we should see the release of all those who find themselves in captivity and distress, in a most peaceful manner.