[Cognitive psychologist Dr. Diana] Reiss points out that the threshold for showing cognitive abilities in animals is much higher than it is in humans, even obviously damaged humans with severe mental dysfunction ... we still believe he or she has essential human qualities, including a cognitive life that is soul-like. Animals, on the other hand, have to perform at nearly superhuman levels to be even considered as having something we might call "mind," whatever that is.
In fact, this is precisely one of the big problems for Reiss. What we call mind tends to be circularly defined as something that humans have. But this kind of definition, even if only implicit, is useless. It creates ignorance in precisely the wrong way -- by appearing to mean something, when it in fact means nothing. This has the effect of stalling inquiry rather than propelling it. As Reiss asks, "Why do we think animals don't think? We begin with a negative starting assumption and then must prove that they do."
Even worse perhaps is that there is an implicit double standard in the thresholds for what is considered proof and how the data are to be obtained. This is what the late Donald Griffin, a Harvard researcher in animal behavior who discovered the sonar abilities of bats, called "paralytic perfectionism" -- setting the standards so high that progress is virtually impossible.
Ignorance: How It Drives Science