The development of the paintings of abstract art in the beginning of the 20th century is characterized by geometric abstraction, first in the development of Picasso's cubism in which the subject would be fragmented or depicted as seen from different viewpoints, both being methods of a highly geometric nature. This process was then developed further by futurists, supremists, contructivists and most notably De Stijl, of which Piet Mondrian is the best known exponent with his paintings consisting of red, yellow and blue rectangles.
Of course not all pre-WWII paintings were such radical examples of geometric abstraction. There were expressionism and fauvism and the paintings of Picasso and his cubist followers rarely reached the level of abstraction that Mondrian's paintings did.
Nevertheless, during the first years after WWII, artists started to regard the legacy of geometric abstraction as a burden and out of touch with the post-WWII reality of poverty and despair. The "cold intellectualism" of geometric abstraction didn't appeal to a new generation of artists to whom spontaneity and authenticity were more meaningful than the clarity and functionality of De Stijl and other proponents of geometric abstraction.
And so a new way of making paintings was created, one was fully abstract but didn't rely on intellectualist methodology but was the result of the artist's emotional and physical engagement. Georges Mathieu: "Speed, intuition, excitement - that's my method of creation".
Art informel is French for "art without form", a term invented by French sculptor Michel Tapié. It is the European counterpart of abstract expressionism which applies to American artists who produced paintings in a similar style. Other names for essentially the same thing are Tachism, Lyrical Abstraction and Matter Painting.
Famous are the paintings by Alfred Otto Wolfgang Schulze, aka Wols, see his "Blue Phantom", below.
Immediately after WWII, when Wols' art started to attract attention, critics regarded Wols' paintings as the product of their times: highly strung, uncompromising, wild and aggressive. While people tend to think their times are unique, in fact human history is a rapid succession of crises, interrupted by short periods of relative calm. These violent mood swings make the human race the archetypal bipolar patient.
Art historians have to take the blame for far too often explaining the style of an artist in personal psychlogical terms, or attribute it to the culture-psychological climate of the day.
In fact, Amedeo Modigliani's work (he lived and painted until 1920) already shows the spirit and some of the methods of art informel and art informel would have occurred with or without WWII or other social or geo-political phenomena. Much of the history of 20th century art can be seen as a damped oscillation, with geometric abstraction (e.g. Mondrian) at one extreme and purely painterly styles (e.g. art informel) at the other extreme. Hence, Wols was one of the first painters to realize the momentum was going in the direction of the painterly approach, and so, as more often than not, his art can be explained in artistic-technical terms, rather than in social terms.
Alfred Otto Wolfgang Schulze (a.k.a. Wols) was one of the last renaissance-men. Rather than caring about social status or practical needs, his short life is characterized by a myriad of activities, each of which he executed successfully, but none of which earned him a stable life. The romantic myth of the "starving artist" is one that has it's origins in the 19th century and was further cultivated by artists themselves throughout the 20th century, but today has a negative, pathetic ring to it. However, men like Wols belonged to those people that "live fast and die young", a life-style which is of all times and by no means unique to artists.
Wols (1913 - 1951) was born in Berlin, Germany, to a well to do family. His father was chancellor of the German state Sachsen, but died in 1929, when Wols was 16 years old. In 1919 the Schulze family moves to Dresden, where the infant Wols develops a love of music and physics and starts to learn to play the violin. In 1930 Wols assumes an apprenticeship at the photography workshop of Genja Jonas. He also studies anthropology in Frankfurt and attends the famous Bauhaus artschool in Berlin, where artist and lecturer Mololy-Nagy advises him to go to Paris, which he does in 1932. Still in Berlin, he is offered the position of concertmaster by director Fritz Busch (concertmaster is the first violinist and "leader of musicians" in an orchestra).
In Paris, Wols works as a photographer and assumes his nickname, when a (French) telephone operator mistakes his (German) name for "Wols". He makes many friends, among which Miró, Ernst and Jean-Paul Sartre, for whom he illustrates some writings. Wols dies in Paris, in 1951, due to the effects of food poisoning.