[dragonwriter]

> Doctrines can't be changed because they're inherently immutable.

If doctrines couldn't change, we wouldn't need to have dogmas (which are doctrines which have been infallibly proclaimed and which, therefore, are, in principle, immutable.)

More importantly than the theoretical questions, church teachings do change, even if that means retrospectively reinterpreting doctrine to change how it is taught while maintaining the pretense of consistency, or reinterpreting something that was previously viewed as doctrinal as something other than doctrine.

This is particularly visible in the area of, say, "when a morally cognizable human exists in pregnancy", a relatively important matter on which Church teaching has changed radically over its history.

[sdegutis]

It's true that advancements in science have led to a more fuller understanding of when a human life begins. But that doesn't mean there was ever a change in the doctrine that human life cannot be aborted during pregnancy. They're unrelated concepts.

[dragonwriter]

> It's true that advancements in science have led to a more fuller understanding of when a human life begins. But that doesn't mean there was ever a change in the doctrine that human life cannot be aborted during pregnancy.

Early forms of the "understanding of when human life begins" were themselves understood at the time as doctrines (and in some cases were doctrine proclaimed by Ecumenical Councils, such as that of the Council of Vienne in 1312.)