International Trade under Imperfect Competition | UGC NET Economics – Notes

Introduction

The traditional theory of international trade, rooted in the Ricardian model and the Heckscher-Ohlin framework, rests on the assumption of perfect competition, constant or diminishing returns to scale, and homogeneous products. Under these assumptions, trade arises purely from comparative advantage—differences in relative factor endowments, technology, or productivity across countries. However, this classical framework fails to explain a large and growing share of observed trade patterns, particularly intra-industry trade (IIT)—the simultaneous export and import of similar or identical products by countries with comparable factor endowments (for example, Germany exporting automobiles to France while simultaneously importing automobiles from France). This anomaly motivated the development of the New Trade Theory (NTT) in the late 1970s and 1980s, pioneered chiefly by Paul Krugman, along with contributions from Elhanan Helpman, Avinash Dixit, Joseph Stiglitz, Kelvin Lancaster, and Marc Melitz. This body of theory incorporates increasing returns to scale, imperfect competition (particularly monopolistic competition and oligopoly), and product differentiation as core explanatory mechanisms for trade.

The central insight of this literature is that trade can occur, and indeed can be mutually beneficial, even between countries that are identical in their factor endowments and technology, simply because trade allows firms to exploit economies of scale while offering consumers a greater variety of differentiated products. This represents a fundamental departure from comparative-advantage-based explanations of trade.

Limitations of the Traditional (Heckscher-Ohlin) Model

Before proceeding to the new theory, it is essential to understand precisely which empirical facts the older theory could not accommodate:

1. Intra-industry trade between similar, developed economies (e.g., trade in machinery between the USA and Germany) could not be explained by H-O, which predicts inter-industry trade based on factor-abundance differences.
2. The Leontief Paradox, where the capital-abundant USA was found to export labour-intensive goods and import capital-intensive goods, cast further doubt on the strict H-O predictions.
3. A very large share of world trade takes place among similarly endowed, high-income countries, whereas H-O predicts that the greatest volume of trade should occur between dissimilar countries (e.g., capital-abundant vs. labour-abundant nations).
4. Trade volumes tend to be larger, and gains from trade often larger, than what factor-endowment differences alone would predict.

These empirical puzzles are collectively addressed by New Trade Theory, which introduces increasing returns to scale (IRS) and imperfect competition as independent causes of trade.

Increasing Returns to Scale and the Basis for New Trade Theory

Increasing returns to scale (IRS) means that output increases more than proportionately with an increase in inputs—i.e., average cost of production falls as output rises. Formally, if a production function \(Q = f(K, L)\) exhibits IRS, then for a scalar \(t > 1\):

$$f(tK, tL) > t \cdot f(K,L)$$

There are two broad types of IRS relevant to trade theory:

• Internal economies of scale: cost advantages accruing to an individual firm as its own output expands. This type of IRS is associated with imperfect competition, since if one firm can produce at ever-falling average cost, it acquires market power and the industry tends toward monopoly or oligopoly rather than remaining perfectly competitive.
• External economies of scale: cost advantages accruing to firms within an industry or geographic cluster as the industry’s total output expands, even though individual firms may still operate under constant or even competitive conditions. External economies are compatible with continued perfect competition at the firm level (e.g., Silicon Valley-type clustering, Marshallian industrial districts).

New Trade Theory is built principally around internal economies of scale, since these necessarily imply imperfectly competitive market structures—typically monopolistic competition.