There continues to be plenty of sloppy thinking on asylum seekers from all parties to the debate, if that’s the word, over the government’s efforts to restart offshore processing. It reached a new peak over the weekend when Labor’s proposed amendments to route around the High Court’s judgment were attacked for failing to pay sufficient heed to Australia’s international humanitarian obligations, or to requirements closer to home, like natural justice.

The first policy priority for a rational, civilised government must be to minimise the risk of people dying trying to reach here. I suggested some measures to that end, involving big rises in our humanitarian intake and a lot more assistance to the UNHCR, last week. That priority should override everything else, including sterile debates about onshore versus offshore processing, whether Australia is meeting its humanitarian obligations or whether lawyers and judges like the government’s amendments to the Migration Act. But that priority is not necessarily inconsistent with some of those goals. It should be possible for Australia to fulfil its humanitarian obligations while minimising the risk to life. Merely “stopping the boats” is not a coherent policy.

If you think onshore processing has no impact on the decision of desperate asylum seekers, whom the UNHCR has been unable to place, to risk a journey to Australia, then you can advocate for a return to onshore processing in good conscience. If you accept there’s a chance it will increase the risk people will try to get here by boat, you have to propose an alternative policy. Otherwise, you’re not offering any sort of moral argument.

There’s plenty of the latter at the moment.

We know what doesn’t work to reduce the risk of people getting in boats. Temporary Protection Visas don’t work. In fact, they actually encourage people to get in boats. TPVs aren’t just an amoral policy, they’re an outright evil, because we know what they lead to. Make your own conclusions about anyone who offers TPVs as a serious policy.

And we know that mandatory detention doesn’t work, if it ever did. We’re spending hundreds of millions of dollars to keep asylum seekers in detention in the belief that detention provides some form of deterrent value. Maybe that worked in the mid-1990s. If it did, it didn’t for very long, as the massive surge in maritime arrivals in 1999 and 2000 demonstrated. Why do we retain mandatory detention beyond the period necessary to screen asylum seekers? And how can the government criticise Nauru as expensive and ineffective when exactly the same criticism can be made of mandatory detention? Labor can’t have it both ways. Either mandatory detention is a dud on the same basis that Nauru is, or it works and justifies the huge amount of money taxpayers spend on it. There’s no evidence for the latter.

And we know that Nauru doesn’t work, for the same reason that mandatory detention doesn’t work: if you face years in limbo awaiting the uncertain prospect of UNHCR resettlement, the idea of spending a year or longer on Nauru before certain resettlement in Australia or another developed country is, like the idea of spending a year on Christmas Island, unlikely to deter you taking the risk.

And we know that turning boats around doesn’t work, because the Howard government abandoned that policy in the face of bloodymindedness from people smugglers and asylum seekers themselves in scuppering boats.

We do know that a heavy investment in policing and intelligence resources in Indonesia has some disruptive effect on people smuggling networks, although how much remains unclear to the public.

All parties have individual elements of workable policies. The Greens want to increase our humanitarian intake to 20,000. Labor has been moving families out of mandatory detention and believes transfer offshore will deter boat arrivals. All sides appear to support continuing to invest resources in disrupting people smuggling networks. The Coalition, however, insists on policies in other areas that have been demonstrated not to work. It even continues to insist turning boats around is a viable policy.

But the basic question for anyone wanting to participate in this debate is, how will you try to minimise the chances that desperate asylum seekers, facing years of limbo while awaiting resettlement, will risk their lives to get here? If you don’t have a rigorous answer to that question, you can criticise the government’s amendments all you like, but you’re not serious about the morality of our asylum seeker policy.