Current clinical practice is based on the principles of evidence-based medicine (EBM) with clinical practice guidelines (CPGs) often serving as a source of information for the medical decision-making process. There are philosophical and ethical tenets underlying this process including those pertaining to patient values and preferences. Despite their importance, these tenets may receive less attention than the empirically derived recommendations in CPGs based on the principles of EBM. The purpose of this article is to provide an overview of the philosophical and ethical underpinnings of the medical decision-making process with a focus on patient values and preferences so pharmacists and other clinicians can appreciate the interplay between science, philosophy and ethics when providing patient- or person-centered care. Appreciation of these discussions should help practitioners to recognize the limitations and challenges when attempting to incorporate population-based evidence into a patient-specific medical decision-making process that often necessitates reconciliation and negotiation between the clinician and patient when striving to provide optimal care.