Conclusion
In 1954, many years before game theory was adopted by industrial economists, Schumpeter had defined as “the principle of excluded strategy” the assumption of price-taking behaviour which had been adopted at one point in the history of economic thought to characterize competition. This implies that for him the previous concept of competition included strategy. This is what we intended to show here: the idea of competition as strategic behaviour used by IO is among the oldest notions in the history of economic thought, and game theory has supplied some tools to deal formally with an idea that has always existed.
Manuela Mosca