Indeed, the greatest argument in favour of euthanasia is the greatest argument against it: It is supremely rational.

After all, we are all going to die anyway and so why, when the end is imminent, should we not go out in a time and manner of our own choosing? It is eminently logical.

And, for that matter, why should that choice be restricted to those with imminently terminal illnesses? Surely people with chronic conditions that subject them to unbearable pain also deserve the right to die when the agony becomes too much.

And of course we all know now that mental health is just as important as physical health and can be just as debilitating. And so obviously anyone who is in such intense psychological anguish that life is unlivable should be able to end theirs with dignity.

Yep, it makes perfect sense. The only problem is that if you’re still nodding your head you’ve just endorsed state-sanctioned suicide.

But the arguments don’t end there. As has been front page news in recent weeks, aged care is incredibly expensive — even if the quality of it is often appalling.

Add euthanasia to the mix, however, and both problems solve themselves. Suddenly the elderly don’t need to suffer anymore and the government saves tens of billions of dollars. It’s win-win.

The same of course goes for people of any age with profound disabilities. Surely it is up to them to decide if their life is worth living.

But, what if there is cognitive impairment? What if the elderly person is suffering from dementia, as three in 10 people over the age of 85 already do? What if the disability is mental as well as physical? Would the decision to live or die then rest with that person’s next of kin? The inheritor of their wealth? Or whoever has power of attorney? The distributor of their wealth?

And of course any thoughtful or considerate person would not just contemplate their own wellbeing but also that of their loved ones. They would hardly want to be a physical or financial burden on their beloved children, whose happiness they have always put above their own.

Indeed, the more civic-minded citizen would also appreciate that old age is a huge financial strain on the health system. A 2007 NSW study found that hospital care for the elderly in their last year of life alone soaked up almost one-tenth of the entire hospital budget. And it got more and more expensive the closer the patient got to death — almost ten times in the last month what it was six months previous.

In other words, were doctors able to estimate how long a patient had to live and give them the option of bowing out a few months earlier they could save thousands or even tens of thousands of dollars per patient?

And here, again, is the problem. It’s not that euthanasia doesn’t make sense, it’s that it makes far too much sense. It is not just a commonsense option for the individual but for their family, their community, the government and the economy. When it comes to making a decision whether or not to end a life that is a lot of pressure to resist.

And what counterargument do we have lined up against this mountain of evidence, this immovable wall of logic?

Nothing. Just a sentimental attachment to our own lives despite the fact we all know they are going to end anyway. It is completely and utterly irrational.

The entire history of humanity has taught us that life is cheap, that the strong kill the weak, and that almost all of us will sink into the soil and be forgotten within a few short generations.

Yet human beings have childishly and nonsensically resisted this immutable fact at every turn. We have invented religions and rationalisations of every conceivable kind to reassure ourselves that our lives are worth something more. We have even fought wars and killed to prove that life is worth living.

Indeed, the very foundation of what it means to be human seems to stem from our ability to see our own death coming and our refusal to accept it. Grave sites dating back 100,000 years have been found with symbolic or worldly goods destined for some imagined afterlife.

Even today militant atheists and secular humanists defend an inherent human right to life or ascribe purposes to human life that transcend mere survival, such as serving a common moral good.

But all of these convictions are ultimately mere superstitions. Rationally speaking, there is nothing inherently good in merely being alive and the moment a person ceases to be so they are free from pain. There is no logical reason for us to exist at all and every reason to suspect that we will probably wipe ourselves out anyway.

And yet the human race persists with this silly and sentimental notion that life must be preserved. In fact we place it at the very heart of our civilisation, be it the oath that we demand of our doctors, the founding document of our most powerful nation or the very premise of democracy itself: that one life is worth one vote and that is what determines who controls us.

Again, this notion is wholly illogical. It is, however, vital.

Indeed, once you start applying logic to the value of a life, its intrinsic value instantly disappears. The founding fathers of the United States didn’t even attempt to offer a logical argument as to why a person should be entitled to life. They merely stated it was a “truth” that they held to be “self-evident”.

In other words, if you have to argue why you ought to be allowed to live then that isn’t really living at all. One’s right to life cannot be measured against the quality or worth of the life they lead or it is a recipe for slavery or genocide — a societal league table or a human cull. The truth is there is no purpose to life: Life is the purpose.

And the dark counterpoint to this is that you can’t argue for the right to die without measuring the right to life. Any legalisation of euthanasia, however well-intentioned or carefully worded, must by its very nature set a threshold at which life ceases to be worth living. A point at which the law will sanction an individual’s judgment that death is preferable to existence. And that is a very dangerous thing to legislate.

The fact is, of course, that human beings make that judgment all the time and the law should not stand in their way. And the fact is that it almost never does. The tiny handful of prosecutions that have occurred in Australia have either been quashed or resulted in suspended sentences. It is well known that doctors quietly assist their patients to die all the time and that is as it should be.

To be honest, someone I love deeply has asked me to take care of them when the time comes and if they were to insist I would do so regardless of the law. I will probably also end up asking someone to do the same for me.

But that is a very different thing to the government effectively defining the worth of a life or the point at which it may legally be taken away, even if it is done with the finest of intentions. Once you set a threshold for the expendability of a human life it is impossible not to think people who reach that threshold will measure their worth against it.

Consider a 90-year-old woman with terminal cancer being cared for round the clock by her exhausted 65-year-old daughter — and yet she is still afraid to die. It defies belief that in a society where euthanasia is a mainstream legal option that she would not feel a degree of obligation to unburden her child, despite her inwardly wishing to hang on. Why should people who want simply to live be made to feel they are choosing not to die?

And on the flip side any euthanasia law would also fail to go far enough for my money. I once argued that the government had no business telling us how we were allowed to have sex. It certainly has no business telling us how we are allowed to die. That is a matter for fate and free will.

All of us know suffering and pain in our lives and for some it will overwhelm us. Death is always an option but that doesn’t mean it should be government policy.

Personally, I envy the bravery of both those who battle on and those who bow out and I salute the people who aid them.

But like all acts of valour it is a deed best done discretely.