For example, we learn in Sanhedrin that if a person is threatened with death unless he allows himself to be thrown on a baby, he may choose to live. Maybe MY blood is redder,' since he does not actively do anything. Rather, it should be taken literally - we do not know whose blood is redder. Through Tosafot's approach we can explain why one would be able to protect his own life even if as a result another life is threatened, as long as he does not actively commit murder. On the other hand, the problem of Ben Petura is still unsolved because he also objects to leaving the water in one's own hands - passive behavior that allows the other's death.
Murder is much more severe than sitting by and letting a person die.
According to this approach, we do not choose inaction as a result of our uncertainty, rather we have decided that murder is worse than not saving a person. Rav Chaim uses this distinction in order to support the Rambam's position against the Tosafot. Furthermore, according to the Rambam's approach, Rabbi Akiva's opinion even forbids passive murder. He views not saving another as merely passive murder, for it also brings about the loss of another's life. Each approach accepts the assumption that there is a conflict between the prohibition of murder and another biblical command, protecting one's own life.