I like to think I'm down with youth culture and its slang. Well, a bit anyway. I understand that the word "sick" can mean "cool", and "bare" can mean "a lot". This is pretty much the limit of my knowledge. But I do like to think I can tell the difference between words that have changed their meaning in a quirky but harmless way, and those that have a damaging knock-on effect.

The evolution of the word "gay" is a case in point. Once it meant carefree or merry. Over time it came to be used to describe a sexual orientation. Now – for many at least – it has been appropriated to mean "rubbish" or "crap". So a word that started out meaning "happy" has ended up being used to denigrate. Well, language changes, doesn't it? Many would see no problem with a shift driven by everyday speech.

It is a problem, however, for those of us – a whole swath of society – who are actually gay, and for whom the word forms an important part of our identity and sense of self. It might not be obvious to those who aren't. But the casual, insulting use of the word, in schools and elsewhere, hurts us. In fact, it seeps into the subconscious. It fuels people's perception of gay people as wrong or bad.

If a young person, growing up gay, constantly hears the word being used to refer to something that's disliked, useless or stupid, they are quite naturally going to feel that reflects on them. They are going to feel disliked, useless and stupid. And young gay people have enough to deal with already. Look at the statistics: 23% of gay or bisexual young people have tried to take their own lives and 56% have self-harmed. This isn't inconsequential squabbling over the use of an adjective. No one is looking to fetter freedom of expression. This is about stopping a new generation of gay people from growing up in a climate of persecution and ostracism.

Gay charity Stonewall is leading a campaign against homophobic language. I share its view that the young people using the word gay negatively are not necessarily homophobic. There is a difference between labelling a statement or action homophobic and labelling someone a homophobe. What is needed is better education – of students and teachers alike.

This isn't a question of punishment, but one of enlightenment. Young gay people have told Stonewall that when they hear phrases such as "that is so gay" they feel ashamed; like they are outsiders. Once again, this isn't oversensitivity, or nitpicking over language that may have been used quite innocently. I believe that political correctness for the sake of it can be counterproductive. No, this is a form of bullying – intentional or not – that has obvious consequences.

But are we fighting a losing battle? Can you really stand in the way of a linguistic change, or the way kids choose to behave in their own friendship groups or the playground? I firmly believe that young people's attitudes can rapidly change once they've been educated about something – I've seen it with my own eyes. I have faith in them. Give them the information they need about the harm being done and they will stop using language that hurts and upsets many of their peers.

Most of the time, young people don't want to offend. They want to understand things and, ultimately, behave well towards one another.

The devil is in the detail when it comes to language that is used to ostracise people. It is the detail that we have to get to grips with. People "tolerate" gays and lesbians; Joe Bloggs "admits" to being gay. Double maths is "so gay". These seemingly minor examples can lead to damaging emotional responses. They subtly undermine and erode confidence. The results are bad for society as a whole.

Language is key. Language is everything. After all, what else do we have?