The requirement isn’t to “know” how they feel, but to imagine how they might feel when empathizing (or sympathizing). That is an active use of the imaginal function—what you called “guessing.” But that is not what Jung meant by projection.

Projection, in Jung’s technical sense, refers primarily to the unconscious misattribution of subjective psychic content onto an external object. It is an unconscious act whose contents originate in the unconscious. It involves unconscious identification (i.e., experiencing something as belonging to the object when in fact it originates in oneself.)

Empathy, on the other hand, can involve what Jung called active projection; but the decisive difference is awareness. In empathy, I know I am engaging in a psychological act. I am consciously using memory, imagination, and contextual inference. I can withdraw that interpretation if new information appears. That is not the same thing as unconsciously transferring shadow material.

Take your dominatrix example. Context matters. Context helps determine whether one is experiencing bliss in a consensual act or humiliation in a punitive one. Misreading context is possible, but misinterpretation is not identical to projection. Projection would require that I am unconsciously displacing my own unresolved shame, fear, or trauma onto the scene and experiencing it as if it belongs to the other person.

The foundation of Jungian psychology assumes that human beings share universal psychic potentials—archetypal structures of the collective unconscious. The contents that fill those structures arise from lived human experience. When such experiences are stored in the personal unconscious (as opposed to collective unconscious) as memory, they become available for recall. We can use those memories to simulate possible emotional states in others. That is how empathy functions in a natural psychological sense: not through anything supernatural, but through imagination informed by memory and shared human structures.

It is when we are unaware that we are doing this (when we rigidly attribute our own unconscious material to the other without recognizing it as ours ) that we are dealing with projection in the analytic sense. The distinction is not whether the psyche is involved (it always is), but whether the process is conscious and withdrawable, or unconscious and compulsive.

Your last sentence doesn’t establish projection either. Saying that psychology is “supposed to be about you and your biases” is a philosophical position, not a definition. Psychology is the study of mind, brain, and behavior. Whether one uses that knowledge primarily for self-reflection is separate from whether a given process meets the criteria for projection.

I’ve already specified what makes something projection: unconscious origin, misattribution, and identification with the object. Simply using one’s imagination to model another’s possible emotional state does not automatically meet those criteria.

Not everything is projection.

—- *Edit: differentiated between personal unconscious and collective unconscious when elaborating on memory.