The world is a frighteningly complex place. Unpronounceable volcanoes spew near-invisible clouds of silica into the sky and air traffic is grounded. Bees vanish all over the world for no apparent reason. A renegade fungus from an outdated pregnancy test is wiping out the frogs in South American rainforests. If that isn't enough, petrochemical-burning executives have doomed the whole world to the slow roast of global warming.

This is not some cinematic dystopia: these are just a few of the really big, complicated problems that confront the planet every day. For the most part we ignore them and trust that someone truly clever, some arcane scientist or engineer, will figure something out. We don't really know who will make the key discovery or who will convince a self-serving political leadership to act in the best interests of humanity. But we do have a model for what this person should be like. By turns brilliant and frustrating, perhaps cocky but usually benevolent, who we really need is the Doctor.

The Doctor has been around for as long as I have. While I have used up precious time learning to walk, talk and use the toilet, the Doctor has saved humanity, the Earth and even the Universe many times. Of course, problems present themselves differently in the Doctor's world than in our own.

For example, as I write this, tens of thousands of barrels of oil a day are gushing from a broken oil well into the Gulf of Mexico. Most likely the blame will eventually be placed on some combination of human error, incompetence, engineering failure and poor enforcement of environmental and safety regulations. Solutions are difficult to come up with and hard to apply.

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Now look at it from the Doctor's point of view. A mysterious explosion aboard an isolated offshore oil rig forces the crew to evacuate before the platform, and sadly some of the crew, disappears beneath the waves. Inexplicably, on the ocean floor, the blowout-preventer valves have been sabotaged. Clearly this is the work of the Sea Devils, advanced reptilian beings from Earth's distant past who once hibernated below the sea bed. With a bit of advanced Time Lord knowledge, the faulty blowout-preventer valve can be fixed, but then the real adventure begins. Are the Sea Devils deliberately contaminating Earth's oceans? Surely the Doctor will be able to negotiate with them and save the world?

There is maleficence behind the accident. People die, the environment is threatened, not by negligence but by an identifiable evil. The Doctor's solution is so much more satisfying than the implementation of new regulations and a long clean-up of the Louisiana swamp.

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I do not mean to suggest that simplifying catastrophe is the key to the Doctor's charm. Instead, it is a unique combination of wits and timing. The Doctor is the triumph of the intellectual solution over brute force. He refuses to carry a weapon (with a few notable exceptions, such as the De-Mat gun in the 1978 Doctor Who adventure The Invasion of Time). In fact, he tells weapon-toting allies to put them away as they may hurt themselves.

The Fourth Doctor's savage companion Leela is forever offering to use her knife on the Time Lord's opponents and is forever disappointed when he disdains the use of deadly force. When the Doctor admonishes her, "please try not to kill anybody", Leela's all-too-serious response, "I will try", only emphasises the absurdity of personal violence.

The Doctor's adversaries have no such qualms. The mighty Sontaran warriors who wage an endless war across the Universe fire their guns at him. The Master, a fellow Time Lord, prefers to use a matter compression gun, and later a laser screwdriver. The Autons (animated mannequins) fire guns hidden in their wrists, while the Cybermen and, of course, the Daleks use a seemingly endless barrage of weapons to bombard the Doctor and his companions.

In our world, such violence begets violence. Russian and American troops are quick to respond to threats with bloody invasions, whether in Georgia or Afghanistan. Shia and Sunni forces perpetuate an endless cycle of reprisal in Iraq. What example does the Doctor set? It is a curiously mixed one. While he eschews personal armaments, he will use makeshift weapons and explosives as they come to hand. Daleks are blown up with some regularity. Cybermen are poisoned with gold and Sontarans dealt a blow to the probic vent at the back of the neck. However, most of these acts are committed by the Doctor's assistants and allies.

The Doctor is at heart a negotiator. He pleads with the Master to join him rather than destroy. He asks the Nestene Consciousness to repent rather than be annihilated. Even the Daleks, the Doctor's most ancient and infamous opponents, are not beyond his compassion.

In Genesis of the Daleks (1975), the Fourth Doctor is sent by the Time Lord High Council to destroy the Daleks at source. On Skaro, the Dalek homeworld, he faces the evil scientist Davros in the act of creating the monstrosities. The Doctor is ready to detonate an explosive in the Dalek breeding chamber. Will he destroy them once and for all?

Other heroes would not hesitate. Ridley Scott's heroine Ellen Ripley does not shy away from destroying the creature in Alien (1979), nor does James Cameron's Sarah Connor vacillate over crushing the T800 in The Terminator (1984). But the Doctor hesitates. The Daleks will bring terror and death across the Universe, but some good will come of them: "many future worlds become allies because of their fear of (the monsters)". Faced with this ethical conundrum, the Doctor chooses not to detonate the explosive, although it is set off by a Dalek shorting the detonator wires.

In Dalek (2005), when the Ninth Doctor meets up with what is arguably the last of the species in existence, he is motivated to shoot it. This is a darker, war-damaged Doctor, one who has committed genocide by destroying Time Lords and Daleks in a zero-sum game. The desire for vengeance swells, but he cannot shoot. It is Rose Tyler, his companion, who gives the order for the Dalek to self-destruct, and it seems relieved to do just that.

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In the Doctor's world, violence is not always met with violence. The motivation for the use of force must also include a consideration of what is morally justifiable. I believe that this is true for our world as well. What if the Doctor were to intervene in Iraq, Somalia or even the Democratic Republic of Congo? The joy of the Doctor is the triumph of reason, the search for an alternative to the cycle of violence.

Because Doctor Who is episodic, the Doctor can be entered into any situation, anywhere and any time. In this way, he can address a multitude of different ills.

Worried about corporate greed? So is the Doctor. On the planet Varos, and in the human future on Pluto, he encounters societies ruled and oppressed by corporate monsters (not figuratively: here they are real monsters). What can he do but side with the oppressed citizenry? He brings revolution and freedom.

Do you get a creepy feeling about stone angels in the churchyard? The Doctor exposes them as quantum-locked predators. Even the spooky crack in a little girl's wall opens a window into the structure of the Universe. Each episode allows the Doctor to unravel new problems and gives the audience the chance to ponder the implications.

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There is an element of the anti-hero in the Doctor. He flies a stolen Tardis and is repeatedly tried by his own people for interfering with other cultures and breaking their laws. The Second Doctor is tried and convicted for "crimes against the laws of time" and sentenced to exile on Earth. The Sixth Doctor is also tried, but not convicted.

Having grown up with the Doctor through the turbulent 1960s and 1970s, I was drawn to the rebellious outsider who could flout authority with relative impunity. Brigadier Lethbridge-Stewart of the United Nations Intelligence Taskforce depends on the Doctor to counter threats including robot yetis, Daleks, Cybermen and more, yet he seems to treat him as a brilliant but eccentric teenager.

Repeatedly, the Doctor must speak truth to power, arguing successfully for alternatives to firepower. I am thrilled by this victory of the erratic genius, a victory of knowledge over ignorance. Even when his genius leads the Doctor to be voted president of the Time Lords, he quickly abdicates and disappears into time and space. One cannot simultaneously "stick it to the Man" and be "the Man".

Imagine the impact the Doctor would have in our world if he were to take on global warming. Recalcitrant American, Chinese and Indian governments would all be persuaded to take intelligent action. In a flash of rationality, carbon emissions would be cut and a new energy era heralded. We too might wish to elect the Doctor as world president or prime minister.

One would think that such a thoughtful hero would always do the right thing, but even in the Doctor's world, actions have consequences. With the return of Doctor Who to our televisions in 2005, we see a much darker story. In the intervening years, the Time Lords and the Daleks have fought to mutual extinction. As expected, the Doctor played a major role in this. The Ninth Doctor seems haunted by his actions. He also has to confront the unintended consequences of his adventures for his companions, as does the Tenth Doctor.

As fun as it may be to imagine oneself as the Doctor, one can also dream of being whisked away by him into the Universe, past, present and future. The planets one could visit, the civilisations to explore ... they stretch the imagination. But then the Doctor moves on.

It's hard for those who are left behind, laments former companion Sarah Jane Smith in School Reunion (2006). The letdown is almost beyond recovery. What could compare to adventures with the Doctor?

There is also the difficulty of leaving the Tardis anywhere near where and when you got on. Rose Tyler is trapped in an alternative universe, Leela on the Time Lord's home planet, Gallifrey, and Peri Brown ends up married to the warrior King Yrcanos. Adric is killed, wiping out the dinosaurs in the process. Travelling with the Doctor is not without risk.

Perhaps it is a reflection of our times that the Doctor is now more nuanced. He has become an agent of chaos. In context he still does the right thing, but now he is also a storm crow. When the Doctor arrives, death and turmoil soon follow.

I believe this is part of a greater trend in our society. No longer do we just cheer for the rebel Luke Skywalker in George Lucas' Star Wars (1977): we now empathise with Anakin Skywalker as he becomes Darth Vader. It is more than yesterday's rebel being taken to task: we are all being called to account.

The giddy investments in a 20-year housing boom have left us with a recession, collapsed banks and empty housing estates. The 1960s baby boomers are entering retirement, and society is left with the spoils of its excesses.

For the Doctor, reckoning comes with regret. The Ninth Doctor may rescue the Fourth Great and Bountiful Human Empire from domination by the Jagrafess via its manipulation of Satellite 5 and all human news coverage, but his interruption of the broadcasts leads to atavism on Earth and the rise of deadly, barbaric game shows, where people are killed for entertainment.

The Eleventh Doctor is also challenged to choose between destroying the Daleks and saving the Earth. Unlike the case for his previous incarnations, the two aims are no longer congruent. The Doctor now has to think beyond the moment. Like our society, he is being called to task for his excesses.

I do not know where the Doctor will venture next. I do know that I will be watching, waiting to see just how he will think his way out of disaster next time.

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