Arbitrary inference is a cognitive distortion in which a judgement of an event is formed in the absence of supporting evidence. Insufficient evidence leads to an erroneous conclusion. Two examples of this are "mind reading" and "the fortune teller error".
Mind reading occurs when you imagine/believe that other people are thinking negative thoughts about you. You are so convinced that people are looking down on you that you don't even bother to check it out. For example, suppose a friend passes you in the school corridor but fails to say hello because he is so absorbed in his own thoughts that he doesn't notice you. You might have jump to the conclusion that, "He is deliberately ignoring me, he must not like me any more." You may have responded to this imagined negative reaction by withdrawal or counter-attack. This self-defeating behaviour pattern may result in a self-fulfilling prophecy and set up a negative interaction in a relationship when none existed in the first place!
None of us are mind-readers, how can you
know what someone else is thinking? You may be right but do not jump to conclusions. Stick to what you can be sure of. If you do not have enough evidence to make a sound judgement, see if you can find out more of the facts before you make up your mind.
Automatic thoughts: My girlfriend didn't eat all of the cake I baked for her. She thinks I'm a terrible cook.
Possible answers: All I know for sure is that she didn't eat all of it. I don't actually know whether she thinks I'm a terrible cook or not. Maybe she just wasn't hungry. I can ask her.
The fortune teller error is when you imagine that bad things are going to happen to you and you take the prediction as a fact even though it is unrealistic. For example, during my panic attacks I used to believe that I was going to pass-out or go crazy. My prediction was unrealistic because never before had I passed out or gone crazy, but my negative expectations made my panic attacks worse. Just like the mind reading error, the fortune telling error could easily end up as a self-fulfilling prophecy. For example, if you believe that your boyfriend is going to cheat on you, it may influence the way you act around him and your behaviour towards him, in such a way that he may feel attacked or controlled and he may seek to break free.
Or if something has gone wrong in the past, it doesn't mean it will go wrong in the future. If you predict the future, instead of trying something different and finding out what happens, you are cutting off the possibility of change. Change may be difficult but its not usually impossible.
Automatic thoughts: I'll never get the main part in that play. I never have.
Possible answers: The fact that I have never got the main part doesn't mean that I never can. If I go and audition again this year I may feel uncomfortable at first, but if I give it my all I might even enjoy the audition. Also other people will respect me for going back and trying again, and I will respect myself. If I don't try I will never know!