Final answer:
Allen Ginsberg is the twentieth-century poet who suggested that material abundance might hide a deeper spiritual emptiness in his poem "A Supermarket in California".
Step-by-step explanation:
The twentieth-century poet who questioned whether "well-stocked aisles mask a spiritual desolation in the midst of material prosperity" is Allen Ginsberg. This line of contemplation is reflective of Ginsberg's critique of America's materialist culture and is evident in his poem "A Supermarket in California". In this poem, Ginsberg uses the metaphor of a supermarket to explore themes of consumerism and alienation, pitting the vibrant, inclusive poetry of Walt Whitman against the backdrop of mid-twentieth-century American grocery stores.
Ginsberg was an influential figure in the Beat Literature movement, advocating for freedom of expression and opposing the conformity of his era. His works, particularly "Howl and Other Poems", brought to light the experiences and issues of marginalized individuals and criticized societal norms. His reflections on America present a dichotomy of abundance and emptiness, where the external wealth of the nation stands in contrast to the internal impoverishment of its spirit.