Subsequently, pressure towards its internalisation will build up in public opinion, the political process or the legal system. This pressure will lead to more specific research and ultimately to the implementation of appropriate incentives for internalisation. By no means all, probably not even a majority, externalities identified by individuals or small groups are being taken up by the mainstream, but only those which in fact affect the well-being of a sufficient number of people in a strong enough fashion to warrant wider concern. If this is not the case, interest will fade quickly.