Current societies are on unsustainable paths, but simple extrapolation of past trends or making a business-as-usual scenario of the future does not help much in planning actions for a more sustainable future. If, for example, the growth of car traffic in the past is projected to the future, the futures study in fact promotes the growth of road traffic in two important ways. First, the future is treated as predetermined instead of deliberately decided which brings about a sense of fatalism - that nothing can be done to change the unsustainable trend (van Vught 1987; Höjer and Mattsson 2000). Second, if the predicted road traffic growth is placed on the current road network, chaotic congestion would seemingly follow. New roads are then planned to reduce the expected congestion. This increases the capacity, or the supply, of road transport which in turn also increases road traffic demand (Owens 1995; Tapio 1996). The process of circular reasoning, that is, ‘make the most probable forecast about the future and adapt to it’, has been described with many concepts in the academic literature. According to Merton’s (1948) concepts, the forecast becomes a ‘self-fulfilling prophecy’ of an unsustainable future. This approach is also known as ‘determinism’ (Höjer and Mattsson 2000) and ‘Comtean positivism’ (Tapio and Hietanen 2002; see Comte 1974). It is often called the ‘predict and provide’ concept in transport research (Owens 1995). However, the future is always uncertain due to the fact that it does not yet exist and thus cannot be directly observed. Major drivers of the observed issue might develop in unexpected ways, and the visions for the future can also influence human action if people actively try to either achieve or avoid a particular future. Instead of deterministic provision of one apparently probable future, the aim of futures studies is to provide alternative scenarios of alternative futures. This helps public and private decision-makers to see the strategic paths ahead and gives guidance of the impact of their decisions in a changing world (de Jouvenel 1967: 101-16). In this way, decision-makers can avoid unsustainable paths and promote the sustainable ones (see Hall and O’Rourke, Chapter 7, this volume).