as straight of a conceptual line as there can be
In Two Treatises of Government (1689) John Locke (English philosopher, 1632 - 1704) made two points pertinent to this modest little essay, one still completely valid and the other not so much. The still-valid point he made is that injustice is “being subject to the arbitrary will” of one or more other persons. The point he made that is not quite accurate is that liberty is the predicate of justice: justice is liberty. On the face of it, if injustice is being subject to the arbitrary will of any other person(s), then justice most immediately requires that we refrain from subjecting other(s) to our own arbitrary (from the point of view of any other person) will. That makes the predicate of justice mutual respect, not liberty — though mutual respect does actually create the maximum liberty that co-existing people can share simultaneously.
David Hume (Scottish philosopher, 1711-1776) made the case that liberty is too conditional to be the predicate of justice. Most generally, that means that there are too many factors related to human life within material existence that impinge on liberty even to be able to talk about it as a meaningful concept. Hume went further, insisting that free will is an essential ingredient of liberty that in reality we humans simply do not possess.
Immanuel Kant (Prussian philosopher, 1724 -1804) said that Hume’s writing, well, “woke” him — from his “dogmatic slumbers.” In one of the very greatest feats of intellectual endeavor in the history of humankind (whether one agrees with any or all of it or not), Kant set out to refute the whole of Hume’s radical skepticism concerning knowledge that Hume imparted in his An Inquiry Concerning Human Understanding. As part of that project Kant took on the issue of liberty. To obtain the radical freedom of will necessary for liberty to have meaning, Kant went beyond that term to “autonomy:” he posited that the will exists in a noumenal (i.e., immaterial) realm where the contingencies of this world cannot reach. In the end, though, rather than liberty (or autonomy) as the predicate of justice, for Kant justice is to be found in his “categorical imperative,” of which he gave a few slightly different iterations, but all of which come down to some version of mutual respect.
G.W.F. Hegel (Prussian philosopher, 1770 - 1831), who is generally considered to be the other candidate for “greatest Western philosopher ever,” agreed almost completely with Kant. As he saw it, though, Kant distanced all knowledge too far from material existence (what Kant called the “phenomenal realm”). That included knowledge of what justice is. Hegel also had a form of mutual respect as justice (“right,” to be completely accurate), but for him that grew out of his understanding of the development of the “dialectic” of the “totality” as it pertained to relations among human beings within material existence.
In “Welfare Economics, Property, and Power” (in Perspectives of Property, Gene Wunderlich and W. L. Gibson, eds.), Warren J. Samuels (American economist, 1933 – 2011) all but defined “social power” as the ability to effect choices, i.e., choose among perceived alternatives and take action to bring that choice to fruition. Samuels was concerned with how the process of effecting choices unfolds and how it relates to power.
Having read enough philosophy prior to encountering Samuels’s compact intellectual tour de force to be convinced that mutual respect has to be the ethic of justice, this author saw Samuels’s insight as a way to bring the issue of justice completely into the realm of material existence. Effecting choices is something we humans have no choice but to do. That makes choosing integral to being human. The ethic of justice is therefore mutual respect among human beings for the capacity of one another to choose, beginning with choosing whether/how/to what extent to be involved in any way whenever any choice is being effected. Here, both the determiner of the ethic of justice (the observation that human beings have no choice but to effect choices) and the referents of justice (actions involving other human beings in any way — which can include ‘speech acts’) are completely contained within the ‘real world’ (i.e., material existence). This particular approach to justice can therefore be called ‘real justice’.
In any iteration of mutual respect there is an obligation on every person to respect all others — to at least some necessary minimum extent. Justice is present when people are (sufficiently) respecting one another in our relations with one another (to put it in the most general possible context).
more about mutual respect as the ethic of justice: “From ‘The Golden Rule’ to ‘Real Justice’” (here in Medium, but not behind the paywall)