The late U.S. senator and one-time ambassador to the United Nations, Daniel Patrick Moynihan, famously rebuked a political opponent: You are entitled to your own opinion, but not to your own facts.

As a society and political system, we rely, especially in Parliament, on a modicum of veracity in our discourse. When serious and complex issues are debated, it is important that their factual basis is accurate. Alas, this has not been the fate of issues surrounding the recently adoptedTreatyon the Prohibition of Nuclear Weapons that Canada has chosen to reject.

More than 120 states, parties of the 1968 Nuclear Non-Proliferation Treaty, deemed it important for the survival of the planet to conclude a comprehensive prohibition on nuclear weapons and the use or threat of use of these devastating and indiscriminate arms. But Canada opted to join a dissenting minority of nuclear-armed states and U.S. allies. NATO members have decided to privilege the alliances doctrine of nuclear deterrence that threatens the use of nuclear weapons under unspecified circumstances over its stated policy to contribute to the creation of a world without nuclear weapons.

This already represents something of a policy muddle. Clarity is not created when the Canadian government attempts to justify rejection of the prohibition treaty by inflating the significance of another diplomatic enterprise it is championing. This is the so-called preparatory group on a Fissile Material Cut-off Treaty (FMCT), which will see 25 countries consider possible elements of the envisaged accord over the next two years.

Read that again: A concrete treaty already negotiated and adopted by 122 states to ban the bomb is pushed aside to pursue a possible treaty to be discussed in the coming years by 25 states to ban additions to the stock of bomb-making materials.

A long-standing aim of the international community, the FMCT would entail a legal ban on the production of fissile material for nuclear weapons but not eliminate material already stockpiled. Negotiations for this treaty have never commenced, in part because they have been assigned to the 65-nation Conference on Disarmament in Geneva. This body, the designated UN forum for negotiating multilateral arms-control agreements, operates under an extreme consensus procedure. No decision, however minor, can be taken without all of the member states agreeing to it. Not surprisingly given conflicting world views the CD has failed to agree on a program of work for 20 consecutive years, rendering it the most dysfunctional of diplomatic forums. The preparatory group Canada is chairing also operates under a consensus rule and will meet behind closed doors.

Minister of Foreign Affairs Chrystia Freeland was the first to embellish reality. In a debate in the House of Commons on June 6, she asserted that in 2016 for the first time Canada had rallied 159 states to adopt a UN resolution calling for an FMCT.

In truth, Canada has taken the lead for many years on an FMCT resolution at the UN that calls for negotiations of this treaty. Calling for negotiations and actually initiating negotiations are two fundamentally different acts. Those interested in international security may have also been puzzled by Ms. Freelands neglect in her statement of any reference to disarmament diplomacy or what Canada might plan to do with the elected Security Council seat it is running for.

On Sept. 20, the date the new prohibition treaty was opened for signature in New York and signed by 50 states, the government was questioned again in the House on why Canada was rejecting it. Transport Minister Marc Garneaus reply distorted reality to an egregious extent. He asserted that in 2016, Canada had led 159 states in signing the FMCT. That is real action, he proudly proclaimed. The fact that the FMCT doesnt exist, that it remains only a long-neglected goal of the international community, didnt seem to intrude into his talking points.

Given that our opposition to the UN nuclear ban treaty echoes U.S. hostility to it, Mr. Garneaus misrepresentation might be an appropriate Canadian addition to the world of alternative facts currently prevailing in Washington.

The annual opening week of the UN General Assembly witnessed an extraordinary exchange of threats, counterthreats and schoolyard taunts. Sounding more like Fidel Castro and Hugo Chavez than any previous U.S. president, Donald Trump mocked North Koreas Kim Jong-un as Rocket Man and described Irans government as a murderous regime. In response, Iranian President Hassan Rouhani condemned Mr. Trumps address ashate speech while Kim Jong-un derided Mr. Trump as a mentally deranged dotard. Russias Foreign Minister, Sergei Lavrov, called for calm in this kindergarten fight between children.

In an escalating nuclear crisis that is ringing alarm bells around the world, with the very survival of humanity hostage to the quality of decision-making in Washington, Moscow, Tehran and Pyongyang, Canadas proud contribution to saving the world is a make-believe treaty.

Paul Meyer is a former Canadian ambassador for disarmament and adjunct professor of International Studies at Simon Fraser University.Ramesh Thakur is a former UN assistant secretary-general and director of the Centre for Nuclear Non-Proliferation and Disarmament at Australian National University

This opinion piece first appeared in the Globe and Mail, Friday, September 29, 2017