If two of the same objects or people from different timelines are brought in close proximity or contact with each other, this creates a paradox because they cannot exist in the same space at the same time. This usually makes things go haywire in one way or the other. Cole demonstrates this with the two watches at the end of the pilot episode.

Terry Matalas has stated that where two versions of the same thing connect, the older of the two items is destroyed.

The result of a paradox includes the destruction or death of one of the objects, and leads to temporal anomalies, including the red leaves and temporal storms.

Examples of paradoxes that have occurred in the show:

• S1E01 Splinter – Cassie’s Watch – in the pilot James causes an explosion at the Markridge facility.
• S1E11 Shonin – The Witness Medallion – the Pallid Man’s medallion and the version Ramse had been given by old Jennifer are paradoxed at the Monkey Mansion, and cause an explosion resulting in the trees all turning red.
• Primary Tommy Crawford – The first victim of the Messengers stabbed by Mantis with the exhumed collar bone of his future skeleton.
• James Cole & his younger blood – James is cured of the damage caused by splintering but the explosion destroys the bookstore, and leaves the Pallid man with permanent scars on his face.
• Primary Melinda – paradoxed by her husband Charlie, a Messenger, with her exhumed collarbone.
• Eliza’s pocketwatch – James generates a paradox explosion at Titan to escape the army.
• Terry the Tortoise – Jennifer causes a distraction in season 3  bringing young and old Terry together.