“The legendary image of…[Rabbi] Abraham Joshua Heschel marching together with [Dr.] King in Selma, Alabama…epitomizes the passion for justice that seems so much a part of the Jewish tradition.” 
The association of Judaism — or of being Jewish — with a commitment to social justice is a strong one. As with almost any statement, uniform agree-ment about this is not quite so simple. There are numerous, almost G’morrah-like discussions — especially online — that explore the questions involved in this from an increasingly wide range of viewpoints. I recommend them.
It’s true that Torah requires personal, individual generosity to redress in-equities in the distribution of goods — especially food. The Talmud continues in the same vein. If, for example, Torah says “…don’t wholly reap the corners of your field…”  — meaning: leave something for the poor to glean for them-selves — the Mishnah  points out that Torah sets no limit as to how much can be left — implying that it’s praiseworthy to leave more rather than less.
The history of “social welfare” is specifically about the structures that socie-ties have created in the attempt to maintain the well-being of their weaker, poorer members. To this day, we’ve not come up with a way to do this that satisfies everyone. (Let’s give ourselves some credit, though — we’ve come a long way from “debtor’s prison.” Does the current environment, though, sug-gest that we could head back in that direction? Or worse?)
Torah tells us, both explicitly and implicitly: We are not free to be uncaring. As to “free will” — well, yes, we’re free to drive our Astin-Martin over a cliff into the sea. But is that wise? Likewise, yes, we’re “free” not to care — but is it wise? Even out of self-interest? Torah tells us: people can be uncaring, but shouldn’t be, if “the world is to stand.”
Concern for social welfare and justice is part of the fabric of Torah. Notice, for example, that the mitzvah of leaving “the corners of your field” is in the same “holiness chapter” that includes “Love your neighbor as yourself,”  separated by only a handful of verses.
But if Torah includes concern for others as part of the overall picture of an ideal society, the prophets — especially Isaiah — insist on its primacy as part of worship itself:
“Behold, this is the fast that I [G-d] consider precious: Let loose the chains of wickedness; undo the bonds of oppression; let the crushed go free; break all the yokes of tyranny! Share your food with the hungry; take the poor to your home. Clothe the naked when you see them; never turn from your fellow …If you remove from your midst the yoke of oppression, the finger of scorn and the speaking of malice; if you put forth your soul to the hungry and satisfy the wretched, then shall your Light rise in darkness and be bright as noon…” 
Do Isaiah’s word sound familiar? They might — they’re part of the Haftarah that’s read during the Yom Kippur morning service!
Torah places “…corners of your field…” near “Love your neighbor…”. The Mishnah strongly urges magnanimity. Isaiah — the most prominent of all the later prophets — declares active concern for the poor and weak to be part of worship itself. The rabbis incorporate his words into the service of the single most important day of the Jewish liturgical year. What are they saying to us?
An earlier, very idealistic, hopeful generation thought that action for social justice is itself part and parcel of worship. Many of them, at the same time, suffered severe psychological, emotional problems. We’ve learned, I think, that Torah’s view (along with the prophets’ and the rabbis’) is the more realistic one. Our worship must combine personal experience of G-d’s Presence and active concern and efforts for the relief of all suffering, near and far, with our continued efforts to do better tomorrow — emotionally, societally and spiritual-ly — than we’re doing today.
“It is only through love that the salvation of mankind will be attained. It is only when [we] will learn to give full expression to the Divine power of love within [us] that bloodshed will cease and war will be no more.” 
Would Rabbi Heschel have agreed?
I hope so.