Answer:
George Orwell wrote under a pseudonym because he had lost his job as an a journalist. For this reason, he felt that it was necessary to create a new identity free of the past associations. He originally wanted to choose another name other than George, but there were several other writers with the same name. So he went with "Eric Blair."
Step-by-step explanation:
George Orwell wrote under a pseudonym because he was concerned that his ideas would hinder his chances of success as an established writer.
The answer is somewhat complex, and needs to start with the author's understanding of what writing meant in Europe at that time. Much literary work was associated him with one faction or another--communist or fascist, existentially heroic or conformist etc.-- and so the dangers to individual writers varied from country to country. In England in particular there was a strong tradition (going back through Charles Dickens) of using a pen name, not for reasons of modesty or any other formality but simply as protection against hostility from political enemies or powerful cultural interests.