Lets look at several definitions from non-medieval sources.
From
Subjectivity | Define Subjectivity at Dictionary.com
noun, plural subjectivities for 2.
1.
the state or quality of being
subjective;
subjectiveness.
2.
a
subjective thought or idea.
3.
intentness on internal thoughts.
4.
internal reality.
From
Subjective | Definition of subjective by Merriam-Webster
: of, relating to, or constituting a
subject: as
a
obsolete : of, relating to, or characteristic of one that is a subject especially in lack of freedom of action or in submissiveness
b
: being or relating to a grammatical subject;
especially : nominative
2
: of or relating to the
essential being of that which has substance, qualities, attributes, or relations
3
a
: characteristic of or belonging to reality as perceived rather than as independent of mind
: phenomenal — compare
objective 1b
b
: relating to or being experience or knowledge as conditioned by personal mental characteristics or states
4
a (1)
: peculiar to a particular individual
: personal <
subjective judgments> (2)
: modified or affected by personal views, experience, or background <a
subjective account of the incident>
b
: arising from conditions within the brain or sense organs and not directly caused by external
stimuli <
subjective sensations>
c
: arising out of or identified by means of one's perception of one's own states and processes <a
subjective symptom of disease> — compare
objective 1c
5
: lacking in reality or substance
: illusory
—
sub·jec·tive·ly adverb
—
sub·jec·tive·ness noun
From
subjectivity - definition of subjectivity by The Free Dictionary
1.
a. Dependent on or taking place in a person's mind rather than the external world: "The sensation of pain is a highly subjective experience that varies by culture as well as by individual temperament and situation" (JohnHoberman).
b. Based on a given person's experience, understanding, and feelings; personal or individual: admitted he was making a highly subjective judgment.
2. Psychology Not caused by external stimuli.
3. Medicine Of, relating to, or designating a symptom or complaint perceived by a patient.
4. Expressing or bringing into prominence the individuality of the artist or author.
5. Grammar Relating to or being the nominative case.
6. Relating to the real nature of something; essential.
And for further reading
Subjectivity - Wikipedia, the free encyclopedia
None of which at all mentions a soul. None of which has ever been an actual definition of the word. There has been a theological opinion that the soul was involved with subjectivity and "choosing" as you say but in English it has NEVER been part of the definition of the word.
What your argument falls down to is that "You don't believe in souls therefore you are a Social Darwinist".
I do not believe in souls. There is no evidence for souls. I believe in subjectivity by any of the above definitions. I could have gone and quoted a dozen other online dictionaries but I just chose the top three as well as a wiki page. Hopefully you will see that as sufficient in at least the definition of the word has nothing to do with souls. If your point still boils down to souls then use those terms instead. However you will have a far harder time proving your point of subjectivity and making everything "fact" when what you mean to say is that I am a pragmatic materialist and you believe in souls. That is the key difference.
And please respond to the portion about brain damage and "subjectivity".