Perception is always selective
The senses have limits, attention selects only part of incoming signals, and memory is not a complete recording of events. Language, previous experience, expectations and current emotional state add further filters.
Two people can therefore describe the same situation differently while both are sincere. This does not mean objective facts do not exist. It means each person's access to them passes through a limited model.
Error begins when the model is treated as fact
Statements such as 'I see' and 'I know' often conceal several layers of assumption. A useful discipline is to separate observation, interpretation and prediction. That makes the probable location of error visible.
The distinction matters especially in conflict and strategic decisions. When an interpretation is presented as unquestionable fact, disagreement quickly becomes a defence of identity.
A strong model can change
The goal of thinking is not to build a picture that never needs revision. A strong model is stable enough to support action and flexible enough to update.
A practical question is: what observation would make me change my mind? If there is no honest answer, the position may have stopped functioning as a model and become part of identity instead.