Question

how can the social, political or economic conditions alter the nature and meaning of art

Answer 1

It seems that LOTS of people are asking the same question online!

http://www.google.com/search?hl=en&q=social+political+economic+conditions+alter+nature+meaning+of+art&btnG=Google+Search&aq=f&oq=

You need to examine the lives of some artists. Here are a few to consider:

Giotti - http://en.wikipedia.org/wiki/Giotto_di_Bondone
Leonardo da Vinci - http://en.wikipedia.org/wiki/Da_vinci
Michelangelo Buonarotti - http://en.wikipedia.org/wiki/Michelangelo
Questions to ask yourself -- How were Medieval influences at work in Giotti's works? How did artists and their works change with the coming of the Renaissance?

And writers:
Wilfred Owen - http://en.wikipedia.org/wiki/Wilfred_owen
Ernest Hemingway - http://en.wikipedia.org/wiki/Ernest_Hemingway
How did wars or the lack of wars affect what writers wrote about and/or how they wrote?

Keep asking questions. Think of different time periods with identifiable social, political, and economic differences -- and explore the different artists' works who lived during those time periods.

In order to answer your own question, you not only have to know about the artists; you also need to understand the times in which they lived.

Answer 2

http://fcit.usf.edu/HOLOCAUST/ARTS/musReich.htm

The meaning of Wagners operas has certainly been altered for me.

http://www.hitler.org/art/

http://www.wpamurals.com/

tp://www.archives.gov.on.ca/english/exhibits/spain/index.html