Psychiatric-mental health nurse practitioner (PMHNP) education often privileges certainty-rubrics, checklists, and single-best answers-despite the ambiguity that defines clinical work. This article advances John Keats's Negative Capability as a pedagogical lens for cultivating wise, ethical practice. The article also integrates Isaiah Berlin's value pluralism to frame unavoidable tensions among legitimate goods (e.g., autonomy and safety) and distinguish internal uncertainty (self-doubt, the urge to fix) from external uncertainty (diagnostic ambiguity, cultural complexity). Rather than rejecting structure, the article proposes a developmental balance: use structure as scaffold while deliberately training learners to dwell within not-yet-resolved situations. Practical strategies include mindfulness "urge-to-fix" drills, reflective journaling with Keatsian prompts, uncertainty-mapping worksheets, culturally grounded cases using the DSM-5-TR Cultural Formulation Interview, ambiguity-weighted OSCEs, and values trade-off conferences. The article braids these tactics to broader nursing and philosophical foundations-Heidegger's ontology of care; Carper/Chinn's patterns and emancipatory knowing; Watson's caring science; and Leininger's transcultural nursing-to clarify links to emotional intelligence, resilience, and epistemic justice. Negative Capability, implemented with clear safety thresholds and just institutional supports, prepares PMHNPs to listen deeply, think plurally, and act responsibly amid conflict and incomplete knowledge. Educators can thus reframe uncertainty from personal deficit to essential terrain of clinical wisdom. It aligns with contemporary nursing priorities and ethics.