By revealing the destructive impact class hierarchy had in 1912, Priestley encourages 1940s society to move forwards towards social equality instead of returning to the old ways
Priestley shows how social class alienates the two groups so that neither interact, and this is emphasised by how we only ever see one working class character on stage
Priestley argues that the upper classes maintain the class system because it benefits them, allowing them to live in ignorance of how the working classes struggle
Priestley suggests that authorities and politicians don't realise that it is possible for one group to succeed and prosper while the other experiences a severe decline
Mr Birling's claims that the country is "in for a time of steadily increasing prosperity" (Act 1, pg 6) and "there'll be peace and prosperity and rapid progress everywhere" (Act 1, pg 7)
Overlooks the poverty, disease, and physical labour endured by the lower classes
Priestley includes their interactions to demonstrate how social class makes people act with ulterior motives and causes divisions where there doesn't need to be any
Gerald Croft comes from a family that is of a higher class than the Birlings (Gerald is from old money whereas Mr Birling is considered nouveau riche)
Mr Birling is keen for the two to marry because it will help him climb the social ladder and grow his business
The Crofts are reluctant because the Birlings' lower social status will degrade them
When Mrs Birling recalls how Eva introduced herself as "Mrs Birling", she is outraged because she thinks it will sully or taint her name if it is used by a working class girl
Mrs Birling: '"I think it was simply a piece of gross impertinence - quite deliberate - and naturally that was one of the things that prejudiced me against her case"'