On a supposed right to lie because of philanthropic concerns

"The moral principle stating that it is a duty to tell the truth would make any society impossible if that principle were taken singly and unconditionally. We have proof of this in the very direct consequences which a German philosopher has drawn from this principle. This philosopher goes as far as to assert that it would be a crime to tell a lie to a murderer who asked whether our friend who is being pursued by the murderer had taken refuge in our house."