The government’s growing political problem around returning asylum seekers to Nauru flows directly from its decision to favour a policy of punitive detention over one of offshore processing for maritime arrivals.

While it constantly uses the phrase “offshore processing”, the government has not implemented such a policy. The status of asylum seekers on Nauru and Manus Island is of indefinite detention, rather than being subject to a finite processing period, and of detention in hellish, punitive conditions in which murder, rape and child abuse have all occurred, in addition to the physical and mental health impacts of prolonged detention.

The offshore processing model proposed by Angus Houston, Michael L’Estrange and Paris Aristotle in 2012 was very different. Detention was proposed to be of a duration limited to a period of time that ensured maritime arrivals received no advantage over asylum seekers who had not tried to reach Australia. And detention was to involve a strong framework of support for detainees to address their educational and health needs while awaiting resettlement. That panel recommended that model fully aware of the mental health impacts of long-term detention — Aristotle noted that such impacts were better than people dying in boats trying to reach Australia.

That was the moral calculus at the heart of their recommendations: offshore processing wasn’t ideal, but if it helped to stop maritime arrivals and the deaths at sea that were a necessary component of maritime arrivals, then it was a justifiable policy. The panel cast that calculus in terms of changing the incentives for asylum seekers — increase the incentive to not get on a boat by substantially lifting our humanitarian intake, decrease the incentive to get on one by preventing any advantage to those who did.

Few opponents of offshore detention will engage with this moral calculus — they dismiss the justification of preventing drownings at sea as a figleaf for hostility to refugees. Undoubtedly for many in politics (in both major parties), and many in the community, it plays such a role. Some opponents also assert — without offering a coherent argument — that “ends don’t justify means”. But that doesn’t wave away the moral implications of adopting any policy that increases the chances of people dying at sea. That is a consequence that must always be considered, even if some hold such a position disingenuously. And responsible policymakers must always consider the consequences of every policy.

But the government’s problem — and that of Labor, which has uncritically accepted every aspect of the government’s treatment of asylum seekers — is that it has instead implemented a kind of nightmare version of offshore processing, and is now having to deal with the consequences in terms of broken bodies and minds. Offers from New Zealand to resettle some asylum seekers have been rejected. The Department of Immigration treated the widespread incidence of rape, sexual and physical abuse of women and children on Nauru as an inconvenience that was nothing to do with the government, until it became too difficult politically to ignore.

Both Labor and the Coalition, in government, failed to provide adequate facilities for the housing of families on Nauru. Medical treatment and access to appropriate services was poor (the government continues to insist medical services for detainees are “on par” with those available in Australia, presumably on the basis that they’re on par with the most remote and isolated communities in the country). Asylum seekers have been essentially left to the mercy of people on Nauru, with rape and physical assault occurring outside the “processing” centre with little apparent consequence for the offenders. And the government put more effort into trying to hide evidence of the treatment of detainees than to remedy it.

Now it faces the choice: does it send profoundly damaged people, especially children, back to Nauru (where, notionally, they are not “detained”) to endure more of the conditions that have damaged them; does it send a five-year-old child who has been raped back to a place where his rapist roams free? Does it perpetuate conditions that may well result in detainees killing themselves and harming themselves?

And this is a self-perpetuating problem: the longer the government maintains its punitive version of “offshore processing”, the more people will be damaged, the more people will be raped and abused, the more people will need to come to Australia to access the kind of services that are required to try to begin repairing the damage done to them.

The government argues that returning them to Nauru is necessary in order to ensure maritime arrivals don’t restart — that, in effect, their suffering is required to prevent future deaths of as-yet unidentified people. But that moral calculus is no longer so straightforward. The government itself has magnified, far beyond necessary, the suffering of detainees for its own political convenience. Moreover, it claims that its boat turnbacks policy has been highly effective in stopping boats reaching Australia. What the government is really arguing, therefore, is that it is required to continue gratuitously punishing detainees far beyond the requirements of policy in order to prevent further maritime arrivals, even though it has another, effective policy in place to prevent maritime arrivals.

“Let Them Stay” is a simplistic slogan that ignores the complex morality of real-world decisions and their consequences. But the government’s reflexive invocation of the need to stop the boats is similarly simplistic — and hides the fact that it has consciously adopted a policy of deliberate cruelty that has destroyed any moral case for what Australia is doing to asylum seekers.