Tate Britain, London, until 31 August
Policing the borders of art is a tricky business. They’re porous, and they’re constantly shifting. What passes as “art” today may no longer pass tomorrow. It’s like nailing jelly to a tree.
This is not a question that torments most of us. But the movers and shakers in the art world are obsessed with it. Either they’ve got millions riding on their favourites or else they’ve erected palaces of high culture around them.
Barbican, London, until 14 September
Digital Revolution opens onto a darkened room lit by code that drops Matrix-style towards the floor, the flashing of video games and the blinking of computer screens. Clips of music repeat over and over, competing with the 8-bit bleeps and bursts from early video games. It’s immediately loud, exciting, daunting and disorientating.
Turner Contemporary, Margate. Until 21 September
Piet Mondrian declared that he was not interested in painting pictures, but that his art was about "seeking truth".
For him, this search came to mean reducing images of the things he saw around him to their most objective essence - to remove the subjective and thereby achieve clarity.
Mondrian's most famous works, the grids, use simple horizontal and vertical lines to separate the bright primary colours of red, yellow and blue to create a "universal harmony". It is easy to see the effect Mondrian's abstraction has had on areas of graphic design and architecture.
Yorkshire Sculpture Park, Until 2 November
Some 25 years after the Tiananmen Square democracy protests, Yorkshire Sculpture Park is staging an exhibition by dissident Chinese artist Ai Weiwei. In his words, "Freedom of speech...is the very essence of human rights", and his work explores freedom and its restriction in capitalist societies.
The park is in the grounds of Bretton Hall, and this exhibition is showing in its newly restored 18th century chapel.
Tate Modern, London, until 7 September
Shortly after Henri Matisse's death the writer and artist John Berger wrote a short illuminating essay on Matisse's work in which he remarked, "I can think of no modern artist with less interest in history or psychology." He was born in the year that the Cutty Sark was launched and died the year in which the first hydrogen bomb was tested.
Iniva, Gallery London, until 17 May
The title of Burak Delier's show is inspired by recent social movements. The artist argues, "When we consider the recent uprisings in Istanbul, Tahrir Square and Occupy New York, we can see that the rioters don't have a programme. Nobody knows exactly how we'll become free."
Burak is a Turkish artist living in Istanbul who has been politically engaged for many years. This is his first exhibition in Britain.
Ashmolean Museum, Oxford, until 22 June
This is the first European exhibition of the Pearlman collection of Impressionist and Post-Impressionist art, and it's a real treat.
Henry Pearlman was a rich American businessman who was as proud of the wheeler-dealing it took to acquire the paintings as he was of the paintings themselves, but don't let that put you off.
Tate Modern, London, until 26 May
Just what is it that makes Tate Modern's current retrospective exhibition of Richard Hamilton's work so different, so appealing? Of course this is a rather tongue in cheek reworking of the title of Hamilton's now iconic 1956 piece, "Just what is it that makes today's homes so different, so appealing?" Hamilton was, I would argue, one of the most interesting, innovative and enjoyable artists working in Britain from the late 1940s until his death in September 2011.
Gallery for Russian Art and Design (GRAD), London, until 29 March
Cinema was in its infancy when revolution in Russia toppled the old order in 1917. From the beginning photography and film were seen as important educators by the new workers' government.
Lenin argued that finance for film should be divided between the popular and a cinema that widened the base of the revolution. For millions film brought the outside world into the their lives. Film could only be "real".
Whitechapel Art Gallery, London, until 23 March
Hannah Hoch was one of the great revolutionary artistic innovators of the early 20th century. Along with Raoul Hausmann, George Grosz and John Heartfield she led the way in developing what has become known as photomontage or collage.
The avant-garde Berlin Dadaist group, of which Hoch was a member, was the most politically developed of the Dadaist groupings that sprang up across Europe and the US from around 1916. The Berlin Dadaists would use their new method of working not as a mere innovative technique in their "art practice" but, crucially, as a weapon.
