More than three weeks after the Mong Kok riot, one of the most frequently asked questions remains: what is the point of putting the blame solely and squarely on the rioters?

What is seldom raised is the much more essential question of what is wrong with a society whose members cannot even agree on what has happened after its worst unrest in years, let along bring themselves to condemn those who planned and participated in the event.

This, in a nutshell, is the most urgent problem Hong Kong is facing. Members of a civil, functional society may have grave, even irreconcilable political differences. This, however, does not prevent them from achieving consensus on basic moral principles that enable them to get along and live together peacefully.

These principles include respect for life as well as the rule of law, accepting the legitimacy of other interests and opinions and renouncing violence as a means of political expression. Those who act against these principles are universally chastised, regardless of their political beliefs and motivations.

So when Joseph Welch, chief counsel for the US army while it was under investigation for communist activities by Joseph McCarthy’s Senate Permanent Subcommittee on Investigations, asked the senator on American national television, “Have you no sense of decency?”, it marked the shifting of the tide of public opinion and the beginning of the downfall of the master manipulator as well as his witch-hunt operation.

Sixty-two years later, this is still how we hold our society’s moral fabric in place– by openly and unequivocally condemning all opinions and behaviour that violate our basic moral principles and sense of decency.

A society is made up of diverse interests. That’s why it will always have its share of political differences and its members will never really get everything they want. But they can live with these differences as long as there is a set of standards for moral behaviour they can agree on.

What clouds the future of Hong Kong is that there are unmistakable signs that its moral fabric is breaking down. It is getting further and further away from the consensual society it used to be. In this deeply divided society, members are quarrelling about everything from whether Hong Kong is a part of China and whether the police have a monopoly on the legal use of violence to whether social justice is an end that justifies all means.

But how can you answer these questions if you have lost your moral compass – a gut feeling or instinctive judgment that makes people know what is right and what is wrong and how they should behave?

Apologists for the rioters want to talk about the failures of the government instead of individual responsibility. There is of course a structural explanation for crimes. If not, they would not be called social deviance. But to blame everything on the system or the status quo is to deprive the criminals of their agency, free will and subjectivity. Like burglars, shoplifters and vandals, they have made bad choices and must be held responsible.

Perry Lam is a local cultural critic