If he did so, then his father never would have been born, and neither would the time traveler himself, in which case the time traveler never would have gone back in time to kill his grandfather.
=== Paradoks starega očeta ===Predmet, ki ga v filozofskih razpravah o času velikokrat oživijo, je zamisel, da če bi nekdo lahko šel v času nazaj, bi lahko nastali paradoksi, če bi lahko spreminjal stvari.