Stories like that of Martin Pistorius (a.k.a. "Ghost Boy") are stunning examples of how impossible it is to really ascertain the cognitive abilities of individuals with special needs (especially if they are nonverbal) and to predict their potential. Of how their abilities and potential can change (sometimes for the better) over time. Of how wrong we can be. And of the damage we can unknowingly cause.
Presuming competence is an assumption that leads to the least dangerous outcomes for the children (and adults) in our care. For there is danger in condemning a child to a life of unfulfilled potential when we restrict their access (education, communication, experience, opportunity, ...life) based on what we think they are capable of or can handle. To presume competence means that we teach with the assumption that kids will learn and grow. It means no preconceived or imposed limitations.
I have come across a few posts written by others that beautifully explore this topic more fully. I encourage you to take a moment to read them.
What to Expect When You Expect Fiona from Star in Her Eye
ReAACtion Therapy and Proof of Competence from Speak For Yourself AAC
Presume Competence from Joy Outside the Box
Knowing vs. Showing from Uncommon Sense
What Believing in the Possibilities Can Do For Learning and Teaching by MindShift
Presume Competence: Why We Have To Keep Saying This from Dynamic Therapy Associates, Inc.
Five Reasons Why Presuming Competence is ALWAYS a Good Idea from Swiftalk
You May also be interested in the following posts:
I Raise My Eyes To Say Yes: A Memoir [book review]