Consider pain:
According to the Logical Behaviorist, the statement that
Johnny feels pain
is reducible to the statement
Johnny has a certain cluster of behavioral dispositions
whereas the usual approach is to say that
Johnny has a certain cluster of behavioral dispositions
because
Johnny feels pain
The Story of the Super-Spartans:
Imagine a world of Super-Spartans. Super-Spartans have the amazing ability to suppress any involuntary pain-behavior whatsoever. No jumping up and down upon stubbing a toe; no jerking of the hand back from the hot stove. Nothing.
The Super-Spartan feels the pain just as much as you and I. Unlike you and I, there are no involuntary pain-behaviors associated with the feeling of pain because, of course, they are Super-Spartans.
The feeling of pain for a Super-Spartan cannot be reduced to a cluster of behavioral dispositions.
What about verbal dispositions to utter “I'm hurt!”, “Damn, that stings!”, or just plain “Ow!”?
The Story of the Super-Duper-Spartans
Super-Duper-Spartans are Super-Spartans who are so good at suppressing pain-behaviors that they never even talk about pain, even when they are experiencing it.
Hence statements about pain are not reducible to statements about dispositions.