Behaviorism is a kind of monism. There are two kinds of monists. The first kind of monist thinks that the only kind of matter is mental stuff. The second kind thinks that there is only physical matter. The second kind is called Physicalism. One version of physicalism is Psychological Behaviorism, which tries to explain mental states in terms of behavior. For example, the emotion of anxiety is just the production of certain behaviors such as sweating, tensing muscles and grinding teeth. Psychological Behaviorists think that we can know everything about mental states by observing behaviors that happen during that mental state.
Philosophical (or Logical) Behaviorists take things a step further. They think that mental states just are behavioral dispositions. When they say that mental states are behaviors, they mean that in the strict definitional sense; this means that there is nothing more to a mental state than just the behaviors. A behavioral disposition is a behavior that you have the ability to perform but you only do perform them if presented with the right kind of situation. For example, the mental state of pain would just be a set of dispositions (which are like tendencies) to exhibit certain behaviors like saying, “Ouch!” or pointing to where the pain is when asked. Having a behavioral disposition to pain means that a person exhibits these behaviors in appropriate situations or contexts, such as being stabbed in the gut with a fork. Logical behaviorists think that pain really is a set of behavioral dispositions.
A dispositional account of a mental state is the way that a philosophical, or logical behaviorist will explain and identify a mental state, such as an emotion or a craving for chocolate. e.g. Desiring chocolate is just (1) thinking about chocolate, (2) eating chocolate when offered chocolate and (3) feeling bodily pleasure while eating chocolate.
Dispositional accounts are always given in terms of inputs and outputs. This means that if a person is given a certain input or stimulus, then they give a certain output, or behavior. The outputs do not need to be actual but only potential. Of course the behaviors will not be actual when a person is sleeping or perhaps very distracted by sports or sex or something. The idea is that a person is, say, nervous if he or she displays nervous behaviors when it is appropriate.
Here is an example of how a logical behaviorist would talk about being sleepy: It is a tendency to have droopy eyes and yawn and fall asleep when one is comfortable and it is nice and quiet. In other words, someone is sleepy if he or she has a behavioral disposition to have droopy eyes, yawn and fall asleep.