Can you imagine a world in which a person’s promise counted for nothing?

It would be a world where contracts had no meaning; a world crushed by the burden of overwhelming surveillance and enforcement provisions; a world where relationships unravelled and families dissolved without hesitation; a world full with transparency and empty of trust.

Promises are the glue that binds society together. They restrain the mighty and underpin the security that comes from a well-ordered society.

Promises are also an expression of our personal freedom, only having force if they are made without duress and based on our free, prior and informed consent to be bound.

So, it’s no small thing when people make promises that they never intend to keep. Not only is doing so an act of ‘bad faith’, it erodes the credibility of a social institution on which so many of us tacitly rely.

It is against this background that one needs to judge the conduct of two members of the Victorian upper house, Bernie Finn and Craig Ondarchie.

They allegedly claimed they each needed a ‘pair’ to be absent from Parliament on Good Friday, as to sit on that day would be at odds with their religious beliefs and therefore violate the dictates of their conscience.

Believing that claim to be true and sincere, the Labor Party withdrew two of its members from the debate about a controversial piece of legislation involving a restructure of the Metropolitan Fire Brigade and the Country Fire Authority.

Having agreed to maintain the balance of representation in the state’s upper house, Mr Finn and Mr Ondarchie then ‘overcame’ their religious scruples and were present to vote against and defeat the government’s legislation at the Good Friday sitting.

There are a couple of fundamental questions that need to be answered by anyone forming a judgement about the conduct of the MPs – and those who may have encouraged or directed them to act against the declared dictates of their conscience.

First, did either member actually make a promise – or was that merely assumed to be the case by a government relying on the conventions of Parliament?

Second, if the specific words “I Promise” were not used, would a reasonable person observing the ‘pairing’ process have assumed that a promise not to vote on Good Friday was being made – and that one could rely on the word of Mr Finn and Mr Ondarchie accordingly.

In other words, did the government have good reason to believe that the opposition members were making some kind of binding commitment? If so, then the substance of a promise had been made.

There are some people who will argue a promise only has provisional force – and that one’s word can be set aside in certain circumstances.

For example, consequentialists have been known to argue that it is ethically permissible to break a promise in service of a ‘greater good’ – a factor that seems to have been instrumental in the decisions of the opposition MPs and their leadership group.

However, even consequentialists are reluctant to see promises broken if the general effect would be to legitimise promise-breaking in general.

Their reluctance is based on the common-sense observation that, for the most part, we are all better off if promises are kept.

That is why we should be especially wary about politicians who break their word.

The more society comes to believe that this is ‘the way politics works’, the less shocked we are and the greater the damage done to our democracy.

After all, if the promises made by politicians count for nothing then how are we, as citizens, ever to offer our free, prior and informed consent to their governing?

Dr Simon Longstaff is Executive Director of The Ethics Centre.