First, do no harm. That should be engraved on the foreheads of all those who breezily call for intervention in Syria.

“Intervention”: is there a more overused, abused or ill-defined term? It’s thrown around by politicians, journalists, soldiers and human rights activists alike. But what does it actually mean to “intervene” in Syria? Supplying arms to unknown and unaccountable rebel groups with dodgy human rights records? Carving out chunks of sovereign Syrian territory for “safe havens” that may not be very safe (think Sre­brenica)? Dropping bombs from 15,000 feet on crowded cities (think Fallujah)?

It doesn’t matter to some. On 10 June, for instance, the Observer’s Nick Cohen made a forceful case for intervention, without deigning to spell out to his readers what his favoured intervention would be. Details are for doves.

And who would the interveners be? Just neighbouring Turkey? Or Turkey plus the US? How about the autocrats of the Gulf? Or the anti-Assad members of al-Qaeda? Do they get to join in the bloodletting, too?

The brutal and loathsome Bashar al-Assad may be responsible for most of the horrific killings in Syria but that doesn’t excuse the terror spread by some of his opponents. Last month, 55 people were killed when two car bombs – attributed by the UN secretary general, Ban Ki-moon, to al-Qaeda – exploded in Damascus. Who mourns these Syrian victims of violence? Who intervenes on their behalf?

Cycle of violence

The truth is that the case for foreign military intervention in Syria, however noble the motives may be, is based on four myths.

The first is that foreign military interventions always save lives. It’s a romantic idea – but it isn’t borne out by the evidence. After Nato’s air assault on Yugoslavia kicked off in March 1999, the number of civilian casualties and refugees in Kosovo went up, not down. In Iraq and Afghanistan, tens of thousands of innocents lost their lives at the hands of western troops as well as home-grown terrorists.

Violence begets violence. Ten months on from the fall of Colonel Gaddafi, hundreds of armed militias are now vying for control of big Libyan cities such as Benghazi and Misurata. “People are turning up dead in detention at an alarming rate,” a Human Rights Watch official announced this year. “If this was happening under any Arab dictatorship, there would be an outcry.” Yes, a potential massacre in Benghazi was averted; on the other hand, the town of Tawergha has since been ethnically cleansed of its black population by rebels who were armed by the west. But we’ve moved on from Libya, just as we moved on from Kosovo.

Myth number two is that the Syrian opposition is united in its demand for foreign intervention. Yet there is no single “opposition”: it’s fractured and disunited. The oft-mentioned Syrian National Council (SNC), a coalition of seven opposition groups formed in Istanbul last September, is in disarray. Last month, three high-profile members of the SNC – the former judge Haitham al-Maleh, the physician Kamal al-Labwani and the human rights lawyer Catherine al-Talli – quit the organisation in disgust. “The [SNC] members are not revolutionaries, [they] haven’t any history in politics, haven’t any history inside Syria,” said an angry al-Labwani. “They bring somebody from outside Syria to represent those who live inside Syria.”

The SNC has been described by former members as a front group for the Syrian Muslim Brotherhood – but that hasn’t stopped the BBC and other western media outlets from presenting it as the sole, authentic, pro-intervention voice of the Syrian people.

Meanwhile, the anti-interventionist National Co-ordination Committee (NCC), another anti-Assad faction, consisting of a dozen or so leftist political parties, doesn’t get a look-in. “We are the ‘other opposition’,” the NCC’s Paris-based spokesman Haytham al-Manna tells me. “But we can’t call on Reuters or al-Jazeera [for support].” Manna, whose brother was killed by the Assad regime, says: “We are against any foreign intervention in Syria.” And he adds: “We want democracy and sovereignty.”

The third myth is that non-violent resistance isn’t an option in Syria – even though the Syrian revolution began as a non-violent mass movement. “When we were non-violent, we had three million people with us,” says Manna. “Now, with the armed resistance, we don’t have more than 50,000 people in the streets.”

In their book Why Civil Resistance Works, the US academics Erica Chenoweth and Maria J Stephan challenge the conventional wisdom that the use of force against heavily armed opponents is the most effective way for resistance groups to achieve their aims. They discovered that the historical record – between 1900 and 2006 – shows non-violent campaigns were more than twice as effective (53 per cent compared to 26 per cent) at securing change – even against repressive dictators.

Diplomacy works

The fourth myth is that there is no diplomatic solution in Syria. Diplomacy, it seems, is a form of appeasement – and it has become fashionable to dismiss Kofi Annan’s peace plan, which rightly calls for an “inclusive Syrian-led poli­tical process” and a complete “cessation” of armed violence “by all parties”, as a complete failure. Yet, as Manna argues, “The only solution in Syria is to rebuild the Annan plan, make sure it is respected [by all sides] and triple the number of international observers.”

And, despite the massacres allegedly committed by militias loyal to the Assad regime, a recent report by the London-based Syrian Network for Human Rights showed that violence in the country is down by 36 per cent from its peak in March, and has declined in every month since Annan’s plan was agreed.

Military intervention will only intensify the violence, not reduce it. There is another way.

As the veteran foreign correspondent and Syria expert Patrick Seale has written: “The only way to prevent a full-scale civil war in Syria . . . is to demilitarise the conflict and bring maximum pressure on both sides to negotiate.”

This should be the focus. We are dealing with a complex conflict in a complex country; simplistic solutions by armchair generals won’t solve it. So remember: first, do no harm.