We develop a two-sector model of monopolistic competition with a differentiated intermediate good and variable elasticity of technological substitution. This setting proves to be well-suited to studying the nature and origins of external increasing returns. We disentangle two sources of scale...

The study considers a stochastic R&D process where the invented production technologies consist of a large number n of complementary components. The degree of complementary is captured by the elasticity of substitution of the CES aggregator function. Drawing from the Central Limit Theorem and...

We derive the aggregate normalized CES production function from idea-based microfoundations where firms are allowed to choose their capital- and labor-augmenting technology optimally from a menu of available technologies. This menu is in turn augmented through factor-specific R&D. The considered...