A leading critic of space exploration contends that it would be wrong, given current technology, to send a group of explorers to Mars, since the explorers would be unlikely to survive the trip  But that exaggerates the risk  There would be a well-engineered backup system at every stage of the long and complicated journey
A fatal catastrophe is quite unlikely at any given stage if such a backup system is in place
infers that something is true of a whole merely from the fact that it is true of each of the parts