Basically, this week a south London school decided to ban slang. Harris Academy in Upper Norwood has put posters up outlawing "innit", "bare", "like" and "extra" as well as the heinous practice of beginning sentences with "basically" or ending them with "yeah".

The school believes its initiative will help students to "develop the soft skills they will need to compete for jobs and university places".

Labour MP David Lammy agrees. He said he hoped they could add the words "s'up blood" to the list. "Speaking slang is fine in a social setting," he told the Daily Mail. "But a school should be a professional, educational environment, and if part of that means banning slang then that's fine by me."

But while most people, young and old, will probably understand that you shouldn't refer to a potential employer as "blood", there seems to be increasing and unwarranted criticism of the language of the young. It is important for people to understand that language must be adjusted according to their situation, but banning certain words seems more likely to isolate the very pupils the school is hoping to assist.

The school may feel as though it is doing its pupils a service, preparing them to enter the interview room with received pronunciation, but do they face making some pupils feel less welcome in the process?

Interested to hear a perspective from a teacher who promotes a different approach to the measures adopted by Harris Academy, I asked Darren Chetty, founder of the Power to the Pupils hip-hop education project, for his thoughts. "Banning [the words] makes a very strong value judgment to pupils and it has an effect on the pupils who use that language," he says. "It situates the school as a middle-class place."

He goes on: "It's the idea that speaking slang is speaking nonsense that doesn't make any sense to me. Where would there be the place for patois poetry and writing that uses dialect? Schools shouldn't be pretending that these languages don't exist."

The decision by the school fits into a long tradition of demonising certain sections of our society for the language they use. The target is often slang associated with the working classes or ethnic minorities. Typically, middle-class people tend to be the ones complaining.

Only last week Nick Harding wrote in the Daily Mail of his disdain for his daughter Millie's use of "multicultural youth English". "Why is my daughter – along with hundreds if not thousands of other children – committing these linguistic atrocities," he writes. "It is heavy with Jamaican and Afro-Caribbean inflections … Worryingly, MYE in all its forms takes many of its characteristics from the misogynistic and expletive-ridden world of rap music." I would be keen to see the look on his face should one day she bring home a black boyfriend.

Last year actor Emma Thompson criticised young people's "sloppy" language. When visiting a school she told pupils not to use slang words such as "like" and "innit", "because it makes you sound stupid and you're not stupid". At least in this case, we can agree that young people are not stupid.

But the problem with these arguments is that they fail miserably to explain why the use of slang is a bad thing in itself, beyond the fact that it's not the language used by its critics: the language of power. If someone is likely to struggle to progress through society if they occasionally slip an unnecessary "like" or "innit" into their conversation then we should see that as evidence of how shallow the values we judge each other by really are.

As for schools, it is important to educate young people about the language of power, but without simultaneously reinforcing that power. Institutions of learning should be about access and inclusion. Teachers should be thinking harder about ways to equip and motivate young people without muting them. Yeah?