"Social Justice" = Lefty Manipulation

While pondering a bit on the words of Leo XIII regarding taxation and Socialism, it became even clearer that the term "social justice" is a very clever manipulation of words. 

...[Socialists] hold that by . . . transferring property from private individuals to the community, the present mischievous state of things will be set to rights [sic], inasmuch as each citizen will then get his fair share of whatever there is to enjoy . . . [This transfer is] emphatically unjust, for [it] would rob the lawful possessor, distort the functions of the State, and create utter confusion in the community . . . Every man has by nature the right to possess property as his own....

... [Although sharing one’s wealth and other temporal blessings is a requirement of Divine Law], it is a duty, not of justice (save in extreme cases), but of Christian charity—a duty not enforced by human law.

Get it?  

Justice is not applicable to a "class".  It is, strictly speaking, only applied to individuals, and one of the purposes of licit government is to apply justice impartially to all.  Here, the collective, represented by government, secures justice for individuals.

Charity, on the other hand, is a mandate which applies to individuals.  It is NOT, properly speaking, a function of government.  It is, in a way, the inverse of "justice," for charity is incumbent on an individual, and that individual (or group of them) may then bestow their gifts on a class (e.g., the poor.) 

But it's far more convenient for the Leftists--the Progressive Hive--to confuse the two.  They can--and do-- "guilt" people by yammering about 'justice,' and in doing so, leverage their tax-collection schemes, which often have the additional benefit of employing Lefty/Progressives as Gummint "charity" workers.

Neat trick!