why the negative assumption

Assuming isn't always a bad thing. It sort of gets you prepared for the truth almost. But negative assumptions can make a person look stupid sometimes. For example, the other day a friend was talking to me about something, and it didn't totally make sense to me. So I automatically turned around and called her a liar without even questioning her. Turns out she wasn't after explaining herself. That made me look stupid and feel stupid. Another example is assuming a person is mad because their "tone" while texting. Just because their "tone" is a little off doesn't mean they're upset or bothered. It could be because they want to reply but they're kind of busy. So yea, never should you ever have negative assumptions. It just doesn't give a positive outlook on you. People look negative when they think negative. It's good to have a guard up sometimes, but the truth is what you should believe, not your negative assumption.