Complex sentence: She highlights the danger if instead of taking into this self-affirming bias, we perceive our and others' reasoning as objective; and how truly objective reasoning is often needed to explore the full range of possible outcomes.
Split into simpler sentences: She highlights the danger if, instead of taking this self-affirming bias into account, we perceive our own and others' reasoning as objective. Finally, she notes that truly objective reasoning is often needed to explore the full range of possible outcomes.