Consistency is a property of distributed databases. Stock Postgres is not distributed, and thus gets strong consistency for free.
There is still a concept of (transaction) isolation levels, and the ANSI SQL standard defines a transaction mode READ UNCOMMITTED that could give you inconsistent results, but Postgres ignores that and treats it as READ COMMITTED.
There is still a concept of (transaction) isolation levels, and the ANSI SQL standard defines a transaction mode READ UNCOMMITTED that could give you inconsistent results, but Postgres ignores that and treats it as READ COMMITTED.