[Steely Tom]

The left believes that reality itself is a social construct. They actually do believe reality is bigoted, because (they believe) the reality which we all experience as members of Western society was constructed by Dead White Males.

Here is an important touchstone of this concept, from The Social Construction of Reality, a 1966 book by Peter L. Berger and Thomas Luckmann. The following quote is from the Wikipedia article on this book:

The work introduced the term social construction into the social sciences and was strongly influenced by the work of Alfred Schütz.

The central concept of Social Construction of Reality is that persons and groups interacting in a social system create, over time, concepts or mental representations of each other's actions, and that these concepts eventually become habituated into reciprocal roles played by the actors in relation to each other. When these roles are made available to other members of society to enter into and play out, the reciprocal interactions are said to be institutionalised. In the process of this institutionalisation, meaning is embedded in society.

Knowledge and people's conception (and belief) of what reality is becomes embedded in the institutional fabric of society. Reality is therefore said to be socially constructed.

[Crazieman]

So if I refuse to believe in dead white men, I can fly by jumping off a building?

[Count of Monte Fisto]

The left believes that reality itself is a social construct.

The useful idiots may believe that crap but the men at the top know what reality is. They have to know. All their power lies in manipulating the perception of reality by the masses. Nonsense like the Social Construction of Reality is designed to confuse and mentally disarm the opposition.