Causality

Causality was the relationship between cause and effect, and the concept that a cause must precede an effect in relative linear time. A causal nexus was a set of causes that influenced an effect.

When the Doctor was young, he was taught by his tutor that "the universe is nothing but a functional chain of causality at every level, governed by the oldest and simplest laws." (PROSE: Longest Day)

The Eighth Doctor told Sam Jones that if he learned anything about future Gallifreyan history, causality could be damaged "beyond all conception." (PROSE: Alien Bodies) He later told Badar that he only made small changes to history to prevent causing any major damage to causality. (PROSE: Interference - Book One)

The Eighth Doctor described Anti-Time as being as destructive to causality as antimatter was to space. (AUDIO: Neverland)

After the Eleventh Doctor freed the TARDIS from a space loop, he stated that there was no longer any danger of the localised time field imploding and ripping a hole in all causality. (TV: Time)

When asked to help save her younger self, Older Amy said, "You're asking me to defy destiny, causality, the nexus of time itself?" (TV: The Girl Who Waited)

Faction Paradox used technology to damage causality. (PROSE: Alien Bodies, Unnatural History, Interference - Book One)

The Edifice began affecting causality when it appeared above Gallifrey. (PROSE: The Ancestor Cell)

At the end of the universe, the laws of causality began to break down. (AUDIO: Singularity)