What is important to remember is that reason can be applied to both. I have noticed that some extreme "T's" and various people do not know how to approach subjectivity and can dismiss it as something like a free-for-all with the assumption that there is no way to apply reason or to organize it into comprehensible systems, but rather it is assumed that each person just creates their own subjectivity and there is no other way to approach it. It is much like those who say that art is whatever a person likes, and assumes that there is no way to analyze or critique it.
I have always been fascinated by subjective systems because they contain a complex integration of different types of data. To apply reason to these systems, one has to tease apart the different elements. Carl Rogers demonstrates this ability in his work because he was a champion of understanding and applying empathy, while also being a pioneer in establishing research methods in the field of psychology. I will use a few different examples of approaching subjective systems.
Pain is subjective because it is experienced inside the person, but it is a complex layering of measurable physiology and internal perception. Because there is an element that cannot be objectively measured, this does not mean that pain is meaningless and useless. Elements of physiology can be measured to determine pain, but it is likely that two people can experience the same level of physical pain, but perceive it differently. To approach pain holistically it is necessary to combine external measurement and empathy.
Art is also a subjective system that has externally analyzable elements and internal perception that come into play in fully comprehending it. An artistic expression contains many symbols, both conscious and subconscious, that represent the ideals, philosophy, culture, and perception of the individual. We can examine these symbols and what they communicate on all of these levels. There are also elements of proportion and inner coherency which can be analyzed using mathematics. I would venture to say that aesthetics cannot be fully comprehended without this understanding of both mathematics and philosophy expressed in a language of sensory-based symbolism. In addition to this, internal perception is relevant in a holistic approach to the arts since they often communicate the artist's personal experience creating a sensory-based visceral empathy.
I find that individuals who are focused solely on "objectivity" have a fragmented approach to understanding the nature of reality. External measurement and fact-building is an important element, but unless the subjective elements are also acknowledged and understood, there is the danger of dismissing relevant information, and there is the danger of not being able to identify when subjective perception is playing a role in interpreting external, objective data.
Individuals who focus solely on personal perception without comprehending these elements within the context of larger, more complex systems, and without acknowledging the impact that the external, measurable world has on our internal worlds, will also have a fragmented and incomplete concept of reality.
Objective, external systems rely on precision of definition and measurement. The tools required to approach these systems are different from what is required to approach the subjective systems of perception and empathy. Subjective systems rely on approximation of definition and conclusion. To create an accurate empathy of another individual's perception and the expression of it, it is necessary to remain open to ever-shifting, ever-clarifying information. If precision of definition is forced onto these systems initially, the result is meaningless.