Motivated reasoning is the motive while confirmation bias is the mechanism

Evidence

The idea of confirmation bias seems straightforwardly related to motivated reasoning in that it is customarily when we are motivated to defend the idea that one of our beliefs is right that we look for evidence to confirm it. We commonly see this mechanism at work in police detectives, who identify a suspect and then try to build a case around him, rather than search for reasons to rule him out. It is important here, however, to distinguish between motivated reasoning and confirmation bias, for they are not precisely the same thing. Motivated reasoning is a state of mind in which we find ourselves willing (perhaps at an unconscious level) to shade our beliefs in light of our opinions; confirmation bias is the mechanism by which we may try to accomplish this, by interpreting information so that it confirms our preexisting beliefs. — Lee McIntyre, Post-Truth, 100

Crucially – and this nuance often gets lost, even in the scientific literature – there’s an important difference between selectively attending to evidence (or being quicker to accept evidence that fits your worldview) and a deep motivation to actively reject evidence because it doesn’t fit with your personal or political beliefs. … All of these terms, including confirmation bias, motivated reasoning, and polarisation often get mixed up, both in the popular media and in the scientific literature, but they actually mean different things. — Sander van der Linden, Foolproof, 120

Categorization

• DEFINE: Precisely delineates motivated reasoning (the state of mind) from confirmation bias (the mechanism) — a useful distinction worth keeping straight.
• corroborated: 3 independent passages support this claim — Lee McIntyre, Post-Truth, 100; Sander van der Linden, Foolproof: Why Misinformation Infects…, 120
• XREF: connects to: Ideologues pair extreme doubt toward disfavored facts with total credulity toward favored ones — Lee McIntyre, Post-Truth, 48; Cognitive bias plus curated information feeds industrial post-truth vulnerability — Lee McIntyre, Post-Truth, 122; People excuse immorality from in-group members arbitrarily defined — Lee McIntyre, Post-Truth, 102 (+13 more)

Broader Connections

• Stereotypes act as hypotheses that bias evidence gathering toward confirmation #exemplifies (0.85) — John F. Dovidio, Peter Glick, Laurie A. Rudman, On the Nature of Prejudice, 1174
• Initial stereotypes bias perception of identical evidence to confirm themselves #epitomizes (0.85) — John F. Dovidio, Peter Glick, Laurie A. Rudman, On the Nature of Prejudice, 1175
• The rational kernel of role-incongruity prejudice gets co-opted by motivated reasoning #exemplifies (0.82)
• Motivated reasoning piggybacks on genuine role incongruity rather than fabricating stereotypes from scratch #exemplifies (0.80) — John F. Dovidio, Peter Glick, Laurie A. Rudman, On the Nature of Prejudice, 209