In the book Brexit: Why Britain Voted to Leave the European Union, Clarke, Goodwin, and Whiteley suggest that certain valence issues, or issues “on which there is a broad agreement among the people and parties about what the policy should be,” are the determining factors that drove and continue to drive attitudes towards EU membership within the United Kingdom (Clark 2017, 68). These two main valence issues, public perceptions on economic conditions and immigration, are the central factors that determined whether or not UK citizens wanted to remain or leave the EU. Understanding these two main issues, the United Kingdom Independence Party, or UKIP, capitalized on these popular concerns of UK citizens and perpetuated the negative perceptions surrounding these policy matters. As a result, UKIP was able to successfully sway the public opinion of EU membership and eventually secure the Brexit vote by focusing their message on the two main valence issues.
The first valence issue, the economy or the perception of the economy, is able to indicate the level EU support since “successful economic performance is likely to increase support for continued membership of the EU while mismanagement of the economy is likely to reduce support” (Clarke 2017, 70). Therefore, perceptions of the economy, evaluated through perceptions of the overall economic situation and unemployment at the state level, will indicate support of or opposition of EU membership. As people increasingly perceive a decline in the overall economy or a rise in unemployment rates, then support for EU membership will decrease accordingly. The more individuals that perceive a declining economy, whether or not the economy is actually declining, the more people that will vote to leave the EU.
The second valence issue, the perception of immigration, similarly demonstrates attitudes towards EU membership since “an overwhelming majority of voters think that the British government should be able to control immigration and there is a consensus that successive British Governments have failed to do so” (Clarke 2017, 70). Since valence issues essentially evaluate whether or not EU membership ultimately benefits the UK and successfully delivers on issues that have widespread support, this negative public perception on immigration will lead to more negative attitudes towards EU membership. As the negative perception of immigration increases, measured through the percentage of the UK population that thought immigration was one of the two most important issues rather than whether or not immigration rates are actually increasing, then more UK citizens will want to leave the EU due to their increasingly negative attitudes towards EU membership.