Ageism, Ableism, and Epistemic Injustice: tracing Absence and Construction in Bioethics and Public Health

Ageism and ableism are intersecting forms of marginalization that shape whose knowledge counts, whose needs are prioritized, and how care is structured in public health and bioethics. While both have been examined separately, their intersection - and the epistemic injustices that emerge from it - remains underexplored in dominant bioethical discourse. Drawing on disability studies, aging studies, and social epistemology, we conceptualize epistemic injustice at this intersection through two interrelated dynamics: absence (the exclusion of marginalized perspectives) and construction (the structural production of epistemic hierarchies). These dynamics manifest not only through testimonial and hermeneutical injustice, but also through institutional norms, policy frameworks, and professional practices that shape what is recognized as legitimate knowledge. Using illustrative examples from dementia care, chronic pain, and healthcare access, we argue that ageism and ableism function as epistemic forces that structure who is heard, what is knowable, and how bioethical discourse takes shape.