saw a declining share of the vote in national elections—from 43.9% in 2009 to 13.2% in May 2012, to 12.3% in June 2012 and 4.7% in 2015—due to its poor handling of the Greek government-debt crisis and implementation of harsh austerity measures. In Europe, the share of votes for such socialist parties was at its 70-year lowest in 2015. For example, the Socialist Party, after winning the 2012 French presidential election, rapidly lost its vote share, the Social Democratic Party of Germany's fortunes declined rapidly from 2005 to 2019, and outside Europe the Israeli Labor Party fell from being the dominant force in Israeli politics to 4.43% of the vote in the April 2019 Israeli legislative election, and the Peruvian Aprista Party went from ruling party in 2011 to a minor party. The decline of these mainstream parties opened space for more radical and populist left parties in some countries, such as Spain's Podemos, Greece's Syriza (in government, 2015–19), Germany's Die Linke, and France's La France Insoumise. In other countries, left-wing revivals have taken place within mainstream democratic socialist and centrist parties, as with Jeremy Corbyn in the United Kingdom and Bernie Sanders in the United States. Few of these radical left parties have won national government in Europe, while some more mainstream socialist parties have managed to, such as Portugal's Socialist Party. Social and political theory Early socialist thought took influences from a diverse range of philosophies such as civic republicanism, Enlightenment rationalism, romanticism, forms of materialism, Christianity (both Catholic and Protestant), natural law and natural rights theory, utilitarianism and liberal political economy. Another philosophical basis for a great deal of early socialism was the emergence of positivism during the European Enlightenment. Positivism held that both the natural and social worlds could be understood through scientific knowledge and be analysed using scientific methods. This core outlook influenced early social scientists and different types of socialists ranging from anarchists like Peter Kropotkin to technocrats like Saint Simon. The fundamental objective of socialism is to attain an advanced level of material production and therefore greater productivity, efficiency and rationality as compared to capitalism and all previous systems, under the view that an expansion of human productive capability is the basis for the extension of freedom and equality in society. Many forms of socialist theory hold that human behaviour is largely shaped by the social environment. In particular, socialism holds that social