Abstract
The concepts of differentiated integration in the EU emerged as a result
of increasing diversification defined in terms of an economic development
level, cultural heritage and nations’ political and social preferences. The principle
of flexibility, which was applied to establish the countries of the ‘hard
core’, allows the EU Member States to implement their enhanced cooperation.
Therefore, the principle is considered to be the main ‘instrument’ for
‘differentiated integration’. The idea of a ‘two-speed’ Europe creates another
category of the EU Member States, which should be supported economically
in order to prevent the ‘hard core’ countries from strengthening.