In early twentieth century scientific and technological advances were changing the world (modernisation). These changes were fast paced and forced people to adapt quickly to the changes in society. 'Modern' and avant-garde was seen as a positive connotation; to 'modernise' was to improve. However, there were various perceptions towards Modernism, some people were pessimistic of the growth of populations in cities and the control of people by machines which would inevitably lead to alienation and pending doom. With Modernisation brought work shifts, everything was scheduled and the whole of life was driven by work.
Looking from another point of view work was high in supply, mass production dominated, making new materials cheaper and more accessible for everyone. Scientific philosophical thinking had made leaps and bounds which started to embrace new thinking, scientific facts were favoured over faith and superstition. Exhilaration, excitement and dynamism was felt by some people, for example, the world had opened up to people through easier travel, travelling greater distances much faster.
After the first world war another response in art emerged that looked for the cause of the modern world viewed from the effect on the relations between people (especially between classes). Socialism sought to use art to help emancipate the people.
Expressionism and Futurism were a response to urban modernisation and tried to reflect the modern world. Cubism did not try to reflect the changes in the outside world in the same way. The subject matter was largely still life and with scenes set up by the artists. However, because of technical innovation cubism was perceived as being the more modern. The appearance had more influence than the subject matter.
Reference - Harrison, C and Wood, P. (eds.) (1997) ‘Art In Theory: 1900-1990', Oxford, Blackwell, pp. 125-9.