If we base a person’s right to dignity, their humanity, on their capacity to suffer, prosper, reason, and choose, then a portion of the population is suddenly no longer worthy of rights or status as a human being. A person with compromised mental function has less ability to reason and choose. As do small children. Does this mean they are worth less? 
Another danger is basing human worth on contribution. If a person is the sum of their contribution to society, then again we get a portion of the population that is worthless. 
An elderly man who has limited ability to work, a veteran who has lost her legs, an infant who is totally dependent on his family. Are they able to work like the rest of us? Nope. Are they worthless? Nope. But why?

 

Watercolor. The process for this one's kinda interesting. I covered the paper with water, then used a wide, soft brush to add vertical streaks of color. I let it dry just a little bit so it was damp but not wet, then with the same brush, using only water and no pigment, made long horizontal strokes through the damp paint. The colors were mixed together in the strokes, creating the sand.  For all of the process I've explained so far, I was mostly just playing about with my colors, not trying to make something specific.
I let the results dry completely, then decided to add the figure walking. The process for the person was closer to my usual methods, just laying down a silhouette and building the colors from there. I painted in the bird later for some added interest.

Brush pen and watercolor. (I messed up the watercolors.....)
More fan art for the comic Stand Still Stay Silent by Minna Sundberg.