Well, if behavior is to be the ‘bottom line’, I’d think it important to examine motives in great length. That, to me, is why beliefs and assumptions are matters of importance. What you choose as sufficient motivation, albeit without sufficient proof, says something about your character and intentions.
Bottom line with respect to what? The law? Yes it is. We don’t put people in jail because of their motivation. On the other hand, people with good motivations can go to jail for their actions.
Think of it this way. Is a person who obeys the laws someone you can depend on to not kill Jews when the Nazis come to power? You can say behavior is more important than beliefs, but behavior over time reflects the power and integrity of one’s beliefs. Belief and behavior are ultimately the same thing. It is only for practical reasons that we distinguish them. For instance, a person who kills a terrorist at the last minute before that terrorist sets off a bomb which would kill thousands of people has broken the law (“bad behavior”) because of good intentions. But really, this is an example of good behavior. Isn’t it?
I think you are bringing attention to the fact that all beliefs and behaviors lie within context and not in cast-in-stone absolutes. I seriously doubt that very many would know where the line between beliefs and their behaviors could be found. What a person thinks they believe and how they might act may not be consistent. Beliefs and behaviors are not the same thing. Most people find themselves surprised by their behaviors from time to time… Beware those who claim consistency of their beliefs and their behaviors.
Then there is no such thing as intent or motivation. What and who you are, and what you believe, is how you behave. So words spoken in anger or a drunken stupor are your beliefs. There is no such thing as “I didn’t mean that”.
Intent, yes. Motives, no […not always, anyway]. Not all motives are discreet or concealable. We need not verify motive without relation to an act, so motive isn’t “unverifiable” so much as useless in such a context.
I can see that the rain outside motivated my coworkers to bring umbrellas, for instance. No communication needed, thanks to inference.
I would also argue that intent can become quite apparent as well, but less so than motives. If you punch me in the face, your intent was to hurt my face. Seems obvious enough.
I, personally, think it behooves us to consider “behavior” without considering things like motive and intent. Our goal is not only to understand the human condition, but to understand it in relation to our environments, circumstances, or contexts.
If you see a guy cheerfully giving out candy to some kids, you might think his behavior commendable. Nothing morally wrong with making some kids happy. However, considering his motives and intent could give you a very different idea about the man and his actions.