Alan Turing famously devised the Turing test, which was intended to test whether a machine can think. If it could show enough behavior consistent with thinking, Turing claimed that it really does think.
Turing tests have come under quite a lot of criticism for relying on the fallacious inference from something appearing to have a certain property to the conclusion that it does have that property. Turing tests take the behavior that follows from genuine thinking to be sufficient to establish that there is such thinking, even if the same behavior can be produced by a computer program. I would take the fact that it comes from a computer program to be sufficient reason to think such behavior can occur without genuine thinking.
So the usual criticism of Turing tests is that they assume thinking is occurring just because the usual behavior resulting from thinking is occurring. While I'm not interested in diminishing that objection, it occurred to be recently that Turing tests aren't just not sufficient for thinking (things that pass the test might not be thinking). They're not even necessary (things that think might fail the test). For one thing, someone who thinks might simply refuse to comply with the test and thus could fail. But more poignantly, someone with a communication-related disorder, e.g. someone with autism and dyspraxia who is completely non-verbal, simply cannot display the behavior the test is looking for. Being unable to communicate is certainly not a sign of being unable to think.
I would argue that more harm is caused by those who take passing a Turing test to be necessary for intelligent thought than is caused by those who take passing such a test to be sufficient for intelligence. We recently attended a communication seminar for parents and educators of non-verbal and mostly non-verbal children. At one session an autistic college senior was present. He can now speak in a somewhat limited manner, but he can communicate by typing on a portable device at a level that's almost certainly far beyond what most kindergarten teachers would have ever expected if they had seen his communication level in his younger years. He had no verbal language until age 12, but because his teachers taught him to type they knew that he was able to grasp much higher levels of thought than most teachers would have even speculated. At last night's session, there was a guy with Down Syndrome and autism who, as far as I could tell, can even as an adult do little more than grunt was typing out sentences that indicate a pretty high-level grasp of some pretty abstract and complex phenomena.
With a son who can't speak much more than five syllables at a time (unless he's singing or engaging in echolalic repetition of Veggie Tales or some other TV show), we've been able to see something like this firsthand. We knew in kindergarten that he was reading fairly complex words for the level of verbal behavior we normally saw, because he'd occasionally see a word and say it. (I remember him saying "banana" one time when there were no pictures of a banana, just the word.) But it's been very hard to get him to demonstrate his intelligence with writing, until this year, with his teacher and support staff working very hard with him to get him typing. Six months ago we could get him to trace over words we wrote out with a highlighter, or we could get him to point to words sometimes on a communication device, which could then pronounce them for him (but they had to be programmed in first, since he wasn't typing them). Now he's showing reading comprehension by completing "because" clauses to answer why certain characters did certain things. It makes me wonder how much he's been wanting to be able to communicate for years but unable to get his mouth or hands to do anything to show it.
The Turing defender might now say that he is able to show it, so it's not an objection to the test, but he's only now able to show it, and there's no reason to think he just started to be able to think on this level. I suspect most teachers would have assumed he couldn't handle the level of math that he's doing (basically right on second grade level) or the vocabulary and reading that he's doing (which is, as I said, at a pretty good level for demonstrating reading comprehension, better than his older brother could demonstrate at that age). He happens to have a teacher with 25 years of experience working with kids like him, who is informed about technology and methods to get kids like him communicating. Many educators encountering a kid like him might well assume low ability levels and not work to get him to communicate. In effect, they're using a reverse Turing test and concluding that someone isn't intelligent because they can't show it in the typical ways.