Inequality, properly
The shape behind the number
Inequality is a shape, not a number. The Lorenz curve sketches the shape — how much of the income the bottom 50% earn, the top 10%, the top 1%.
The X-axis is cumulative population (poorest to richest). The Y-axis is cumulative income. The diagonal would be perfect equality: 10% of people earn 10% of income, 50% earn 50%, etc. Real distributions bow downward — the poorer slices earn less than their share of the population would imply.
The Gini coefficient is the area between the equality diagonal and the Lorenz curve, divided by the triangle. 0 = perfect equality; 1 = one person has everything. It's a useful single number — but it loses information about where the bow is.
Two countries can share a Gini and need opposite policies. One country's Gini might be driven by a missing bottom 50% (poverty alleviation is the lever). Another country's same Gini might be driven by a runaway top 1% (tax / antitrust is the lever). Same coefficient, different cures.
Read the curve, plus three numbers: top 1% share (where wealth concentrates), bottom 50% share (where deprivation lives), and the median / mean ratio (how skewed the distribution is). The Gini is a headline; these are the diagnosis.
Read the curve, not just the coefficient.
Every inequality argument is a fight about which slice of the curve matters. People arguing past each other usually disagree about the slice, not the math. Knowing the shape lets you identify what someone actually thinks the problem is.