Socialism: Life Through Rose-Coloured Spectacles.

One of the many problems with the left is their absolute failure to see reality as it is actually is.
Immigration: they do not spot that the country is full.
The EU:  they believe that it should work - so it is doing.
Crime and punishment: They themselves are often socially responsible - so others must want to emulate them.
Benefits: They believe that nobody actually wants to be on them.

The worst of all is that so many believe in the basic goodness of Mankind!