Over the past two years, counter-radicalisation practitioners have regularly asserted a potential link between autism, mental illness and terrorism. But, underneath the bold headlines, those same agencies and researchers clarify that no causal relationship exists between the three, and that it is rare for people with learning disabilities or mental illnesses to become involved in terrorism. Why, then, is the association continually made? Andrew Silke has referred to Alice in Wonderland to describe this as a ‘Cheshire cat logic’ – one that cannot find evidence of clinical disorders in terrorists, but instead makes vague assertions about pathological personality characteristics. I argue here that by associating mental illness and autistic conditions with terrorism, mainstream society offloads its discomfort with violence. Society cannot understand how someone would commit terrible atrocities against civilians, so it is easier to assume the perpetrator is incapacitated or ‘not like us’ somehow.