I would rather not be writing this column. To argue against the course of action I'm discussing is to tolerate collusion with a murderous regime. To argue in favour is to risk promoting wider human suffering. The moral lines are tangled and the progressive response is confused: perhaps it is unsurprising that this issue has attracted little public discussion. Should we or should we not support wider economic sanctions on Syria?

I felt obliged to tackle this question when I discovered last week that Shell, the most valuable firm listed on the London Stock Exchange, is directly connected to the economic interests of Bashar al-Assad's government. It has a 21% share in the Al Furat Petroleum Company, 50% of which is owned by the state. Ghassan Ibrahim, CEO of the Global Arab Network and a prominent opponent of the regime, tells me that the government permits foreign companies a share of its booty only if they can offer expertise it does not otherwise possess. As much of the wealth produced by Syrian state companies goes into the pockets of the elite, it seems clear that if Shell were not useful to the regime, it would no longer be there.

Shell says: "We condemn any violence and the human rights abuse it represents and we have deep concern over the loss of life … we comply with all applicable international sanctions." But, though complying with current sanctions, it is enriching a government that is violently repressing peaceful protest. The regime has killed some 2,600 Syrian people since March. Its interrogators have tortured and mutilated its prisoners, cutting off genitals and gouging out eyes.

The likely outcome of Shell's investment is that Assad has more money to spend on soldiers, weapons and prison cells. The argument for forcing Shell and other investors to leave and for finding further means of starving the government of money is a strong one.

But no one with an interest in human rights can be unaware of what happened when western nations applied sanctions to Syria's neighbour, Iraq. No one who has seen it can forget the CBS interview in 1996 with Madeleine Albright, Bill Clinton's secretary of state. The interviewer pointed out that half a million children had died in Iraq as a result of sanctions. "We think the price is worth it," Albright replied. The sanctions on Iraq could scarcely have been better designed to cause mass mortality. But even measures that are narrower in scope and applied more humanely will add economic distress to the suffering of Syria's people. Sanctions broad enough to hurt the government's ability to deploy troops will also be broad enough to hurt the people they are meant to protect.

And if not sanctions, then what? So far the only alternatives on offer are vacuous condemnation and demands from the likes of Nick Clegg that "it's time for Assad to go", which, in terms of efficacy, is like being mauled by a giant sock.

So far the European Union has imposed travel bans on members of the regime and frozen some of their assets. The impact is likely to be limited, not least because Assad and his close associates are said to have stashed far greater sums beyond the reach of the EU (and beyond the reach of any kind of scrutiny or accountability) in Swiss banks. It wasn't until May that European governments decided to impose an arms embargo on Syria, which tells us more than is comfortable about their priorities. But better late than never.

More recently, Europe banned the import of Syrian oil. Because the EU imported over 90% of Syria's oil, because oil provides 25% of state revenue and because the state has a monopoly on its sale, this would have stung – had Italy not insisted that the ban be delayed until mid-November. This gives the government time to find new customers. An investment ban, which would reduce the value of assets that enrich the political elite, could hit the government much harder.

The obvious means of resolving this question is to ask the Syrian people what they want. But there is no clear consensus. Of the three opponents of the Assad regime I've consulted, two are in favour of wide-ranging sanctions, one is against. Chris Doyle, director of the Council for Arab-British Understanding, who has spoken to a much larger number of dissidents, tells me that "Syrians are hugely divided on this issue". Almost everyone in the protest movement supports sanctions aimed specifically at members of the regime and their businesses, but they are split over wider measures, such as the EU's oil embargo.

Ghassan Ibrahim told me that opponents of the government recognise that "freedom is very expensive and you have to pay the price. Let's pay it once and for good." He argues that sanctions are likely to be more effective than they were in Iraq, as the regime's resources are smaller. Even today it can scarcely afford to sustain its army. The government's oil revenues provide few benefits for the people.

Samir Seifan, a prominent economist who sought to reform the regime, argues in favour of a wider embargo, including sanctions on investments in the oil and gas sector. This would, he concedes, hurt people because of its impact on industry, farming, transport and electricity, but it also restricts "army movements which are using a huge amount of oil products". Others have argued, Doyle says, that as well as hurting the people more than the regime, sanctions would give Assad an excuse to blame the Americans and Europeans for the economic crisis he has caused.

So I posted the question on Comment is free, in the hope that Guardian readers would help to resolve it. There was a big response. It provided no clear answers, but it helped to clarify some of the issues.

The most widespread objection to the sanctions was that the governments imposing them are selective in their concerns and lacking in moral credentials. This is true on both counts. This column is discussing sanctions on Syria only because they are being imposed there, rather than on Saudi Arabia or Bahrain, which are also run by violently repressive regimes. Far from restraining them, the UK and other European nations continue to supply them with a hideous array of weapons. Though both the UK and the US committed the crime of aggression in Iraq, there is no prospect of sanctions against them. This is the justice of the powerful.

But these concerns, while valid, do nothing to resolve the question. You could just as well argue that because the grisly Russian and Chinese governments oppose further sanctions, they must be a good idea. The brutality of Assad's government is not altered by the nature of the states that oppose him, or by the incoherence and self-interest of their foreign policy. We must make our own moral judgments.

The division on this question among Syrians, the difficulty in predicting the outcome of measures that might help and will harm, a repulsion from collaboration pitched against a fear of aggravation, lead me to an unusual place for a polemicist. There is no right answer.