Alan Johnston told a press conference after his release yesterday morning, "They did threaten my life a number of times. There was one 24-hour period when they seemed to get very angry and chained me up, but that only lasted 24 hours."

When you enter that netherworld of captivity, two fears seize you: you will be tortured and you will be killed. Fortunately, Alan Johnston escaped both fates and emerged from captivity with the dignity that had marked his years as a correspondent in the Gaza Strip. Not all hostages of Islamic militants or American security have been so lucky.

It was never easy to be a western hostage in the Middle East. It became even more problematic when western governments, led by the United States, got into the game in 2001.

Until then, those of us who were kidnapped could plead against violent abuse on the basis of reciprocity: don't do this to us; we would not do it to you. That plea looks a bit thin after Guantanamo, Abu Ghraib, Bagram and the fatal beatings of Iraqi civilians like Baha Musa by British soldiers.

In 1987, when Hizbollah kidnapped me in Lebanon, one of my captors said, "This is not so bad for you. You will learn how prisoners feel. You will understand what our prisoners go through in Israel. You will feel for prisoners everywhere."

Perhaps. I did not know what ordeals Hizbollah prisoners were enduring at Khiam, a notorious interrogation centre in south Lebanon that Israel abandoned in 2000. Khiam's prison became a museum of the crimes committed within its walls until last August, when Israel bombed it to dust - erasing the physical reminder of what its forces did.

Like Alan Johnston, I may have been chained, blindfolded and underfed. But I was not tortured. No one placed a urine-soaked sack over my head, forced me to stand for hours in an agonising crouch or suffocated me with the now-infamous treatment known as water-boarding. (One American, CIA station chief William Buckley, was tortured and murdered.) As an American, I may have been paying taxes to support Israel, but my country was not actually holding people without trial and subjecting them to what the US Constitution calls "cruel and unusual punishment."

After the 2001 assaults on New York and Washington and its invasions of Afghanistan and Iraq, the US became a torturing nation. During the Vietnam War, it had tortured people. Afterwards, Congress put a stop to it, even if the government provided training and equipment to torturers from South America to Indonesia. In 2001, the US took up the torturer's burden again. Britain joined in, covering up CIA rendition flights and abusing prisoners in Iraq. How can western hostages demand humane treatment on the basis of reciprocity?

When captors - Americans if you are a Muslim or Muslims if you are a westerner - pick you up, you disappear. You are vulnerable to whims and caprice. People from your country and the other side are making deals you know nothing about. You are expendable. Whether you die or achieve your liberty is someone else's decision. Your impotence is total. Except over your thoughts. The Israeli-Palestinian poet and former political prisoner Fouzi al-Asmar wrote: "With all the might of their hatred that tears this life apart/They cannot put my mind in jail."

You listen for clues - as if a guard's tone of voice will tell you he is going to kill you or let you go. Your senses are sharpened. You escape in sleep and dreams, remembering your life and imagining your life to come, if it is to come. The injustice of it - of you, an innocent, as Alan Johnston is innocent, being deprived of your freedom - is as galling as it is irrelevant. Who you are is overshadowed by what you are: someone from the other side to be used to gain an advantage.

Your captors do not care about you. They did not care that Johnston had been one of the bravest reporters, who told the world of Gaza's suffering under occupation. Perhaps Donald Rumsfeld, who used to phone instructions to US interrogators in Iraq, deserved it. Maybe Alberto Gonzales, who contrived the pseudo-legal basis for torture in violation of the US Constitution, deserved it. Alan Johnston did not. Yet Alan Johnston was available because he lived among the Gazans in order to document their lives.

Outside your cell, things are happening that you know nothing about. In 1991, Iraq was driven from Kuwait; Iran no longer needed western hostages in Lebanon, so they were freed. A few weeks ago, Hamas took by force what it had not been allowed by the elections it won democratically. With sole power in Gaza, Hamas negotiated Alan Johnston's freedom.

Today, another journalist, Sami al-Hajj of al-Jazeera television, remains in Guantanamo. What will it take to set him free? Shouldn't those of us who demanded Alan Johnston's freedom now demand his?