Marshall and Walras: Incompatible bedfellows?

The standard view about the relationship between the Marshallian and the Walrasian approaches is that they are complementary to each other. My aim in this paper is to show that, on the contrary, they constitute alternative sub-research programmes within the wider neoclassical paradigm. I make my point by contrasting the two approaches against the following benchmarks: the purpose of economic theory according to Marshall and Walras; their views as to the role of mathematics; their specific ways of tackling complexity; the conception of equilibrium underpinning their theories; and, finally, their trade organisation assumptions.