Yes, it is an option. It should fail as fast as possible, that's why you have contingencies in place. For instance, the Space Shuttle's computers checked their results against one another. If a discrepancy was detected, the computer would be immediately voted out. In case all computers were compromised, there was yet another computer with different hardware and software.

The point is that any erroneous result would cause the offending computer to be voted out immediately. And that's what you want, otherwise the system will appear to work fine, while being in an undefined state.