way along the street from each end — each would still draw half the customers but customers would, on average, make a shorter journey. However, neither shop would be willing to do this independently, as it would then allow the other to relocate and capture more than half the market. Deviating assumptions When people along the street, or along the range of possible different product positions, consume more than a minimum number of goods (i.e. have discretionary income), companies can position their products to sections where consumers exist to maximize profit; this will often mean that companies will position themselves in different sections of the street, occupying niche markets. When prices are not fixed, companies can modify their prices to compete for customers; in those cases it is in the company's best interest to differentiate themselves as far away from each other as possible so they face less competition from each other. Political Science Especially true in the American two-party system, political parties want to maximize vote allocated to their candidate. Political parties will adjust their platform to comply with the median voters' demand. The Comparative Midpoints Model represents this idea best: Both political parties will get as close as possible to the competing party's platform while preserving its own identity. Application The street is a metaphor for product differentiation; in the specific case of a street, the stores differentiate themselves from each other by location. The example can be generalized to all other types of horizontal product differentiation in almost any product characteristic, such as sweetness, colour, or size. The above case where the two stores are side by side would translate into products that are identical to each other. This phenomenon is present in many markets, particularly in those considered to be primarily commodities, and results in less variety for the consumer. An extension of the principle into other environments of rational choice such as election "markets" can explain the common complaint that, for instance, the presidential candidates of the two largest American political parties are "practically the same". The candidates elected during primaries are usually established figures within their own partisan camps. Electors in the middle of the political spectrum are more likely to be swing voters, and there is a tendency for the candidates to "rush for the middle" to appeal to this crucial bloc. The assumption is that people will choose the candidate with a