Critical rationalism was developed by Karl Popper in the middle of the 20th century. His premise is that society developed by solving problems through trial and error. Popper's ideal society is a society which is open to this form of problem-solving. False theories are perceived as false and rejected. Critical rationalism allows unfettered criticism as this form of criticism can lead to a genuine possibility of societal change; in short, an open society. These ideas also provide an opening for accessing philosophical ideas.