Abstract
From the time of its birth, Popper 's theory of falsifiability has been fiercely criticized from various viewpoints. In the author's view, however, those various criticisms all have the same root in their assumption that a falsification must be certain and conclusive. As the theory of falsifiability has never had such an assumption, it is the source of misunderstanding. By discarding it, we can reply to every criticism and thereby clarify the role of falsifiability in our search for better knowledge; that is, it makes our attitude open to a yet unknown world.