Why do people so readily judge on assumptions?

People easily judge on assumption because it easily for a person to assume then to ask other of what really is the matter. The judgement made on assumption can be changed as easily as they were made. As a famous quote says "We're good judges for other and good lawyer for ourselves."

Because they usually don't want to find out for them selfs how people truly are, they'd rather go on what other people say

I feel that people so readily judge on assumptions because these judgments are true in their own lives.

People judge based on familiarity. If you are a completely nice person but look like a stereotype that someone may not like, they'll assume that that is what you are. Keep in mind that the majority of people are not this shallow and do what you want regardless of what someone may think.

This is something I've experienced a lot. I feel like people take one look at me and think they've got me all figured out. It doesn't matter how much the real me contradicts what they've cobbled together in their head. They will cling to their assumptions rather than acknowledge they were wrong and start to see me for who I truly am. From my experience, I think this can be chalked up to ego. People don't like to admit when they're wrong; they don't have that kind of self reflection. So they hang on to their assumptions and first impressions instead, regardless of how it affects the relationship with the other person.

For some people it is easier to assume that what they believe to be true is correct, rather than to hear all the facts. In my situation, this often happens when dealing with someone that is stubborn.

Simple answer is – because it is easy. Succumbing to initial reaction or assumption requires no effort, no introspection, no thinking or reflection on the situation – it is automatic and easy. We all have our different sets of life experiences, prior knowledge and exposure, sets of beliefs that constitutes our sense of identity. These factors guide what our automatic first assumptions are (for example, someone who has been chronically physically or verbally abused in the past is more likely to automatically assume that another individual is a threat and an enemy that they have to either beat or hide away from). These assumptions are not meant to be maladaptive and at one point in our lives perhaps they have served as adaptive, they guided us to chose the best action plan given the information, they protected us and may have given us an advantage. However, automatic assumptions become maladaptive when the life circumstances change significantly. It takes effort and time to change your automatic assumptions. This means that you have to be patient with other people who hold faulty first assumptions and patient with yourself when re-evaluating and working on yours.

People tend to judge others on their own assumptions because that is what they are conditioned too. The pretty girl is mean, the jock is a jerk, the smart people are nerds, all these assumptions are engraved in our minds by media and society. So it is quite difficult for a person to rise above such prejudices and think based on what they observe rather than what they think they should observe. However, it is completely normal to make a silent judgment about someone. One should not let that judgment affect the conversation and keep an open mind towards others.

It's something that we all do because we are humans and don't always think before we speak. We assume we know something about someone and are so often wrong. There is no answer as to "why" we do it, it's just part of our human nature.

we all do it. its human nature.. they judge people based on the outside rather than learning about whats on the inside. they judge by what they see first: your appearance. How you look, what you're wearing, if you're "pretty" .. all that. Which actually doesn't even matter at all.