In 'An Inspector Calls', Priestley depicts society in 1912 as capitalist-ruled, segregated and unfair, using the Birling family as a symbol for all upper-class aristocrats. The character, Inspector Goole, acts as Priestley's social mouthpiece to portray the idea that socialism is the future.
Priestley uses the character of Inspector Goole to promote the socialist idea that we need to take responsibility for both our own actions and our attitudes towards others. He contrasts this with the selfish, uncaring, prejudiced Mr and Mrs Birling who don't understand the need to take responsibility for their actions.
He also felt that if people were more considerate of one another, it would improve quality of life for all. This is why social responsibility is a key theme of the play. Priestley wanted his audience to be responsible for their own behaviour and responsible for the welfare of others.