I hadn't thought of it that way but you are right. The difference I see is that even though a baby can't say I'm conscious they can laugh, giggle, cry, scream make all sorts of verbalizations and movements of all their body parts arms, legs, eyes, head.
Terri can laugh but does she cry or giggle or make all sorts of verbalizations short of actual speach?
She is not able to move other than turning her head and blinking her eyes right? I mean she can't walk or sit up on her own. She can't pick up a pen a write.
We can't actually say whether or not she can think all we can say is that she can speak or write or sign i.e. she can't communicate.
I'm sorry I know I'm still having a hard time making my point.
I kind sorta think you have to be able to think to laugh appropriately.
Also-Terri used to say mommy and, horrifically, HELP ME, which used to break the heart of a nurse who tended to her and gave an affidavit on her behalf that Judge Greer ignored.