By making the theoretical objective of firms flexible and consistent with observation they are able to relax ridiculous requirements such as "free entry and exit and perfect knowledge of the future" and get realistic results.

We - myself and co-author Brendan Markey-Towler - have released a working paper outlining a new theory of return-seeking firms. And to our surprise, what seems a rather minor change in the firm's objective function leads to a variety of results consistent with the empirical record, and with many alternative theories of firm production and pricing (such as mark-up pricing).

What did we do?

First, we relaxed the assumptions about market conditions. Rather than the unrealistic free entry and exit and perfect knowledge of the future which define most models, in our world firms face uncertainty, have irreversible costs, and can delay investment to future time periods. As per real options theory, these conditions give rise to our firm objective of return maximisation.

Next, we allow competition to enter the model via the shape of the firm-specific demand curve. The firm specific demand curve can be specified to include the supply of other firms producing substitute goods, and the parameters of the curve can be varied to reflect differing intensity of competitive pressures.

We do this because the usual model condenses similar products into a single market, yet there are almost no examples of markets where the goods produced by different firms are perfectly interchangeable. Hence, competition is a process of return-seeking between firms competing in close substitute goods. This conception of competition also predicts non-price competition which aims to reduce the price sensitivity of customers, such as loyalty schemes and other incentives, and of course, product differentiation.

Because of the way market competition is conceived in our new model, there is no need for the arbitrary conceptual leap between a downward-sloping market demand curve, and a horizontal curve faced by a firm in a competitive market. All firms operate in their own markets, whose demand schedule is influenced by the offerings in substitute markets.