And here is my opinion: the so called "paraphrased" definition by Macpherson of the term "racism" is not a paraphrased definition at all, but a made up definition offered for comment as a strawman argument.
Compare:
Exhibit A - Macpherson's definition
A racist incident is any incident which is perceived to be racist by the victim or any other person.
Context - The Macpherson Report
Exhibit B - DavidofHook's "paraphrase" of Exhibit A
if a person believes that racism has occurred then it is indeed racism
Context - strawman argument