Of course, rational fear of danger can and does save lives, through the fight or flight response hard-wired into all of us, and by promoting prudence and caution.

But so much fear is irrational, based on ignorance or on prejudice – conscious or unwitting. This sort of dread is the cause of much ugly and pathetic behaviour and is all the more lamentable for the fact that it is so unnecessary and so damn demeaning.

In recent days, there have been hideous examples of what can happen when fear goes wrong. 

Case one. A 32-year-old designer, model and co-owner of a hair salon was brutally bashed in the St Kilda Botanical Gardens, where he was peacefully celebrating at a picnic, along with his husband James and others, a friend's birthday. Homophobia is all about fear – irrational, unfounded fear. 

As I wrote here a few weeks ago, most people are decent and kind most of the time. 

We should feel profound sympathy and compassion and outrage for Bryce-Maurice. And we should feel a kind of sadness, pity really, too, for those four men. Bryce-Maurice's wounds will heal, although he will probably remain traumatised for a long time. The damage that has caused his four assailants to be able to do what they did might well never be erased. What influences have they had on them? It is dreadful to contemplate.

We all have a responsibility to call out such influences wherever and whenever we encounter them. Fear can lead people to be bystanders, and that must be resisted and overcome in the name of decency and kindness, of humanity. We owe it to ourselves and to each other, for without it we are diminished and degraded.

There were many bystanders in case two, where two young people died, causing unfathomable heartbreak, because they and others failed to have rational fear.

Harley Churchill, 19, and Ivana Clonaridis, 18, were killed when Churchill lost control of his ute, which sped off a bridge and exploded after hurtling 100 metres through the air.

Before the preventable tragedy, they had attended an illegal street meeting of young drivers. Where is the one among them who will stand up, rather than stand by, and have the courage to call for and show some smart fear and help prevent the loss of precious lives, for so much dumb death is being courted?

A final note on homophobia and fear. Bryce-Maurice was with his husband. Which means they must have married somewhere other than Australia, or use the term without legal backing, for we are yet to join the ranks of enlightened, fair nations that have recognised the right of same-sex couples to marry.

Preventing people in love from marrying is an injustice rooted in irrational fear, and is a terrible reflection on our nation. The vast majority of people in Australia now support marriage equality. When we end this unfairness, which we will, the only thing that will happen is people in love will, well, get married.

It's the sort of progress and decency that might, just might, help decrease the sort of fear that drove the attack on Bryce-Maurice.

As to instilling the sort of fear that would have left Churchill and Clonaridis with the mysterious and miraculous gift that is life, and prevented the agony those who loved them are now in, if the sight of the fate they suffered does not do it, maybe nothing will. And that is terrifying.