Final answer:
The ethical principles in conflict when a pharmacist must choose between patient need and a promised visit are justice and fidelity, requiring the pharmacist to balance equitable treatment with the commitment to patients.
Step-by-step explanation:
When a pharmacist encounters a scenario in which they must choose between a patient who has a greater need and a patient who has been promised a visit, the two ethical principles in conflict are justice and fidelity. The principle of justice demands equitable treatment and fair distribution of health care resources, while the principle of fidelity involves upholding promises and commitments to patients. A pharmacist must navigate this dilemma by balancing the obligations to treat patients fairly and to honor the commitments they have made.