This revisits The Model Mind, but starts from the viewpoint of responsibility for self and others.

Jesus said, "Love thy neighbor as thyself."

This is obviously a translation, probably from Latin, itself a translation from a copy of the Greek version, recalling what had to have been spoken in a dialect of ancient Aramaic.

But it's the thought that counts. 

There are two views of that. One view is of apparent physical realities. The other view is of the actual personal, internal, spiritual origin of all thought.

The very concept of responsibility is inherently spiritual. That is the ultimate stumbling block encountered by all attempts to explain the origin of our physical reality.

At every level, spirituality is about awareness of others. The viewpoint cannot exist without a point to view. Existence is compounded of a sequence of such experiences. Conceptually simple, yet unimaginably complex when the shear number of available points to view is considered.

This complexity is immediately confounded by the awareness that each of these available points to view is itself inherently another viewpoint.

Go ahead, consider the possibilities. 

Any sequence is countable. But when each step in a sequence involves a choice among multiple possibilities, the likelihood of any two sequences being the same quickly becomes vanishingly small. Add the idea that each initial starting point is unique, and the possibility of any two sequences being the same becomes zero.

Suddenly we are faced with the possibility of an infinite number of possible sequences of experience, all different. But it is pointless to dwell on that prospect for too long. Because each new instant offers a new unique starting point. 

Back to the idea of responsibility. If awareness is an evolution of experiences of otherness, then each instance of otherness observed must include an awareness of another sequence of experiences, that forming the other awareness.

Awareness is not a static thing. Awareness is an ongoing evolution. You evolve. I evolve. All otherness evolves endlessly. Changelessness is only apparent. We can't go back to what was. There is only more actual experience, never less. 

Love thy neighbor as thyself. However it is said, this is a definition of responsibility. It is about agreement. It is about acceptance. It is about the endless give and take of existence. It is about awareness of awareness. 

Responsibility starts with awareness of the accuracy and integrity of ones own understanding. Including ones understanding of the accuracy and integrity of the understanding others have.

It is sometimes said, "Let your conscience be your guide." Conscience includes a self-assessment of how well one is sustaining ones own responsibility. This is an ongoing act, a constant burden.

Where does the idea of a guilty conscience fit in? Does it come from ones own failures to accurately predict the future? Much as we know that the future is inherently unpredictable for any individual, circumstances can lead to a self-assessment of failure. Perhaps when this happens we must simply accept the lesson and move on.

But guilt seems to come naturally from the tendency to evaluate oneself in comparison to others. This can happen in two ways. One is to compare oneself to another who seemingly made better choices, and seeing that as ones own failure. The other is to compare oneself with others who seemingly made worse choices, and accepting that as sufficient evidence of ones own better success.

The guilt comes when, in forgiving the perceived failures of others, we accept that as justification for knowingly lowering our own standards, expecting forgiveness. Guilt comes from knowingly violating our own integrity. The temptation toward this may come after an unknowing violation is forgiven, or is seemingly inconsequential. 

Having experienced guilt, we may want to make amends. But what is done is done. We cannot change the past. We can only strive to avoid repeating it.

As don Juan Matus observed, it requires impeccable intent to forget the past and face the future without guilt or fear of consequences.

That may be the best definition of responsibility.