For several weeks now, our army and navy have been in a state of high alert, bravely facing a deadly threat to our very existence: 10 little boats trying to reach Gaza. These vessels are carrying a dangerous gang of vicious terrorists, in the form of elderly veterans of peace campaigns.

Benjamin Netanyahu has affirmed our unshakable determination to defend our country: We shall not let anyone break the blockade to smuggle rockets to the terrorists in Gaza, who will then launch them to kill our innocent children.

This is a kind of record even for Netanyahu: Not a single word is true. The flotilla is not carrying any weapons — the representatives of respected international media in the boats provide assurance of this.

If the flotilla had been allowed to reach Gaza, it would have been news for a few hours, and that would have been that. Israel's total mobilization, the training of the naval commandos for capturing the boats, the acts of sabotage carried out in Greek ports, the immense political pressure exerted by Israel and the US on the poor, a bankrupt Greek government — all this has kept this minor initiative in the news for weeks now, drawing attention to the blockade of the Gaza Strip.

What is this blockade for? To terrorize the Gaza people into overthrowing the Hamas government, the victor in democratic elections? Well, it didn't work, did it? To compel Hamas to change its terms for a prisoner exchange which would release Gilad Shalit? That didn't either. To prevent the smuggling of arms into the Strip? The arms are flowing freely through a hundred tunnels from Egypt, if we are to believe what our army tells us. So what purpose does the blockade serve? Nobody seems to know.

As a result of world pressure following last year's flotilla, the blockade was eased considerably. But Gaza manufacturers are still prevented from getting their products out of the Gaza Strip — thus condemning most of the population to unemployment and abject poverty.

The same goes for the disgusting trade in human remains. Netanyahu promised to turn over the remains of 84 “terrorists” (both Fatah and Hamas) to Mahmoud Abbas as a gift. At the last moment, he reneged. His people make believe that these remains, by now hardly identifiable, may serve as bargaining chips in the game for releasing Gilad Shalit.

The same goes for the actions against the fly-in of international peace activists though Ben-Gurion airport. All they wanted was to go to Bethlehem and Gaza, which can only be reached by crossing Israeli territory. Almost a thousand police officers were mobilized to meet that threat.

All of these unthinking knee-jerk reactions: We must be strong.

THIS is an interesting phenomenon: People see innocent-looking elderly human rights activists on their TV screens and believe they are seeing dangerous provocateurs, because the government and most of the media tell them so. Sinister “Arab and Muslim” individuals are hiding in the boats. An Arab American on one boat has been unmasked as somebody who has collected money for a Hamas social institution.

The phenomenon of people seeing something and thinking they are seeing something else has always intrigued me. How can people not believe their own eyes but believe the eyes of others?

This week I got an e-mail message from a man who remembered something from the time he was a pupil of my late wife, Rachel, in first grade.

Rachel asked him to raise his right hand. When the boy did so, Rachel said: “No, no. That is your left hand!” She turned to the other children and asked them, which hand it was. Following their teacher, they shouted in unison: “The left! The left!” Seeing this, the first boy started to waver. In the end he conceded: “Yes. It is the left hand.”

“No, you were right in the first place,” Rachel assured him. “Let this be a lesson to all of you: if you are sure that you are right, insist on it. Never change your view because other people say the opposite.”

Quite by chance, straight after reading this testimony, I saw on TV the results of a scientific investigation by Israeli researchers into “instilled memory”. Their experiments show that people who have seen something with their own eyes, but are told by everybody else that they have seen something else, start to suppress their own memory and “remember” that they saw what the others had allegedly seen. Neurological research then showed that this could actually happen in the brain: The imagined memory replaces the real. Social pressure has done its work: the instilled memory has become real memory.

I believe that this is even truer for an entire nation, which is, of course, composed of individuals. I have seen this many times.

For example, for 11 months before Lebanon War I, not a single shot was fired from Lebanon into Israel. Against all expectations, Yasser Arafat had succeeded in enforcing a total cease-fire even on his Palestinian opponents. Yet after Ariel Sharon started the war, practically all Israelis clearly “remembered” that the Palestinians had shot across the border every single day, turning life in Israel into hell.

I call this “Parkinson’s in reverse” — while advanced Parkinson’s patients do not remember things that happened, these patients do remember things which never happened.

THERE is a mental disorder called “paranoia vera”. Patients adopt a crazy assumption — e.g., “everybody hates me” — and then build an elaborate structure around it. Every bit of information which seems to support it is eagerly absorbed, every item that contradicts it is suppressed. Everything is interpreted so as to reinforce the initial assumption. The pattern is strictly logical — indeed, the more complete and the more logical the structure, the more serious is the disease.

Among the accompanying symptoms are belligerent behavior, recurrent suspicions, disconnection from the real world, conspiracy theories and narcissism.

It seems that whole nations can fall victim to this illness. Ours certainly appears to have.

The whole world is against us. Everybody is out to destroy us. Every move is a threat to our very existence. Everyone critical of Israeli policy is an anti-Semite or self-hating Jew.

It has been said that paranoiacs also have real-life enemies. The trouble is that the paranoid by their offensive and distrustful behavior, create more and more real-life enemies.

The slogan “All the world is against us” may easily function as a self-fulfilling prophesy.

Israel is not the only country to suffer from this affliction. At some time, the Germans have been afflicted. So have the Serbs. Unfortunately, the costs of paranoia are very high.

So let us start to behave like sane people. Let the little boats go to Gaza. Let arrivals at Ben-Gurion airport go to the Palestinian territories and pick olives, if that's what they want. Even if we do behave like a normal nation, Israel will continue to exist.