Conclusion

So we see that many artists use art as a way of expression in order to give their opinion. In the present case by criticizing society or some of its decisions to show their disagreement.
It is easy to notice that no matter the period, in the 20th century with Rockwell or in the 21st century with Ai Weiwei and Pavlenski the artists have always sought to challenge the power. These artists have all given of their person that they live in a dictatorship or a democracy because they have the same goal: to make the spectator react, to push him to question himself but we also see that without the help of the media (by example twitter or the press) some of these artists would still be in the shadows and their efforts would be useless and unknown to the public. So we can ask another question: is their message heard by the viewer?