Doubt
Our senses are only able to capture a small percentage of the world around us. Taking that incomplete information as a starting point, our brain relies on a series of unconscious processes to construct an image of the world – and sometimes it gets it wrong. Subsequently, it will interpret that image consciously, but in doing so the brain is influenced by prior knowledge, experiences, memories, frames of reference, among other things.
Clearly, this is anything but reliable.
In order to truly comprehend the world around us, scientists must avoid these kinds of errors. Luckily, they dispose of a handy toolbox: the scientific method – a series of unambiguous agreements about how one can gain knowledge as objectively as possible.
At the same time, scientists must always take into account the possibility of getting it wrong. At all times, they have to be doubtful and remain critical, for the sake of others and their own sakes.