Here is a possible restatement of the topic and thesis for The Curious Incident of the Dog in the Night Time:
Ed Boone was justified in lying to protect his son Christopher's fragile mental state.
Though Ed Boone lies to Christopher and suppresses truths from him, he does so out of paternal love and a desire to shield his son's fragile condition. Ed understands Christopher's trouble coping with ambiguous or upsetting information, and filters the world around him to avoid distressing him or exacerbating his anxiety and tendency towards mathematical logic and formulations. Though Ed's approach is unconventional, he acts in Christopher's best interests and with the aim of supporting his well-being and development despite his challenges. Ultimately, Ed's lies and omissions emerge from caring, not deception, and are therefore justified.