The First Impressions Fallacy

The default habit of some where a person is judged based on "first impressions," which almost inevitably involve total assumptions about their worldview or personality or talents (if applicable), is something practiced exclusively by the irrational.  There is often nothing to go off of but emotional perception or how the observed person fits into meaningless cultural norms--though it is not as if knowing someone for a longer time truly bridges minds [1].  The fool tries to participate in whatever sociocultural bullshit their community encourages or forces upon them, maybe even joyfully.  

This kind of person either makes assumptions about others based on very limited exposure (all assumptions are assumptions, though, so no one is justified in having unproven beliefs about others even with more exposure) or they want to bend over backwards to be arbitrarily judged according to someone else's personal biases and cultural constructs about politeness or some other nonsense.  Suppose that someone has a brief verbal/observational encounter with a stranger where the latter is perceived to be arrogant or brutal.  On the level of language, intention, and the actual concepts being communicated, there was no actual harshness, but the former person perceived there to be illusory abrasiveness and, on the basis of how things appeared rather than how they were, made an assumption.

All language is ultimately ambiguous since one is not experiencing any mind but one's own, and one can only know with absolute certainty what one's own words mean, but there are certain things that would almost certainly mean someone is irrational even in an initial conversation.  If someone says that logical axioms are false, that a secondary historical source is as relevant as a primary one, or that Nazism is morally good in your first encounter with them, they are an idiot, yes.  They could change for the better, but the first impression is indeed damning.  They are not a rationalist if they at all mean the standard definitions by those words.  However, things like a supposedly arrogant attitude without any accompanying words or deeds to point towards actual arrogance are irrelevant.

Perhaps the person in question really is arrogant, but mere outward perceptions cannot ever reveal to you the interior of other minds, and simply perceiving how they "come across" to oneself is not even direct evidence of their mental states, much less proof.  Misunderstanding this during a first and potentially only meeting and then fallaciously rejecting the logical possibility of improvements with time, some people not only make assumptions (even proudly), but they also never acknowledge how a person might change for better or worse after a first encounter.

This has consequences for everything from philosophical conversations with non-rationalists (they remain slaves to assumptions and will possibly hate you without any justification) to job hirings and more.  Combined with other biases, someone guilty of the "first impressions fallacy" only sinks more into stupidity and might be genuinely hostile towards someone they do not even know beyond cursory observation.  Non-rationalists can think they are rational for making assumptions, usually selective ones that already appeal to them, but they are worms that fall far short of superior philosophers.  Reality is not knowable through the laziness and haphazard nature of assumptions.

[1].  https://thechristianrationalist.blogspot.com/2022/04/the-gulf-between-minds.html