One of the expectations in the ongoing debate over marriage reform in Australia is that all views should be respected.

But if we want to uphold the values of the enlightenment and of deliberative democracy, then whatever side of the debate you are on, demanding views be treated with respect is a flawed idea.

This may sound contradictory, but it goes to a point too often missed in such circumstances: people are worthy of respect, ideas are not.

We naturally adopt a respectful attitude to people. At this basic level, people have to work hard to lose our respect, and, even then, we may choose not to disregard them because we value human life and dignity.

We appreciate that they contribute in some way to the social norms we all enjoy, and that they, like us, are creators of society as well as participants in it.

Ideas have no such empathetic traction. Unlike people they cannot suffer, they do not know joy, and they do not contribute by themselves to the happiness of others.

That is not to say there are no really good or really bad ideas.

But they do need to stand or fall exclusively on their merits, and often within their own contexts.

They should be subject to critical scrutiny and survive only though articulation and argumentation.

The fallacy of deepest offence

It may be painful to acknowledge, but what we view as a core belief to us may be seen differently by others. Even if we feel that the belief is a strong part of our identity.

Like all ideas in a free society, it must be permissible to subject that core belief to open inquiry.

To assume that an idea may not be questioned because it is a part of your identity, and that an attack on it is an attack on you equivalent to a denial of human respect, is a fallacy. I call this the fallacy of deepest offence.

It is a blurring of the line between people and ideas. It is a device by which ideas are rendered immune to critical inquiry behind the claim of deepest possible offence: an insult to human dignity.

Failing to recognise this fallacy creates two problems. The first is that we lose the ability to reflect on our own internal processes.

If we do not look inwards and question what we see, we ossify — led more by our creed than by our critical faculties.

The second is that we become less tolerant of others, less willing to work collaboratively, and less able to comprehend arguments. Both of these diminish our ability to contribute and to coexist.

If you want to believe that the world is made of snow, that women are inferior to men, that homosexuality is morally wrong, or that relationships between people of the same sex should not be legitimised through marriage, then go ahead.

But the instant you take that belief into the public arena, your idea will be rightfully tested.

The minute you suggest others should believe it too, you will be challenged.

When you ask that the taxes of your fellow citizens support your belief, you will be resisted. This is exactly how an open society operates and should operate.

Your ideas are not immune to criticism just because you express them with sincerity.

Ideas need arguments, not assertions

Our arguments are our rational probes into the world. When they work, we can feel that we are on solid intellectual ground.

When they do not, we know we need to refashion our thinking or to consider more deeply how our arguments are received by others.

Our arguments are not only designed to make our case publicly, but they also challenge us to look closely at our own reasoning.

Sorry, this video has expired Tony Abbott and Trent Zimmerman on same-sex marriage

When proponents of the status quo on marriage ask for respect, they have every right to receive it. But they have no such right for their views.

If robust analysis of their arguments shows up their weaknesses, then offence, or claiming a lack of respect, is not an option. The onus is on them to create a better argument.

The Australian Christian Lobby, for example, lists four assertions on its website as to why same-sex marriage should not be permitted:

redefining marriage will threaten your freedom of speech

redefining marriage will threaten your freedom of speech redefining marriage can take away your religious freedom

redefining marriage can take away your religious freedom redefining marriage is the step before redefining gender itself, and

redefining marriage is the step before redefining gender itself, and redefining marriage will take away children's rights — every child deserves a mum and a dad.

Some of these have recently been repeated, equally devoid of justification, by former prime minister Tony Abbott.

The lack of logical or evidentiary support around these claims is breathtaking. Nowhere on the ACL's website are found reasons supporting these claims, let alone complete arguments to analyse and evaluate.

So by all means let's be respectful in the marriage equality debate.

Let's refrain from focusing on the person and play the ball instead.

But let's not assume that means an absence of demand for rational engagement.

We should hold people to task for the views they express and make it clear that if they are not prepared to craft a cogent argument, their slogans are nothing more than gang colours.

To claim offence when questioned is not only to commit the fallacy of deepest offence, is also to disrespect utterly the right of your fellows to engage in honest inquiry, and that is a very deep offence indeed.

Peter Ellerton is a lecturer in critical thinking and director of the UQ Critical Thinking Project at The University of Queensland.

This article first appeared on The Conversation.