KNOWLEDGE
What do we know as fact and what things are reasonable for us to believe? Where do we obtain reliable information?
There are basically two sources: knowledge gained by personal direct observation and knowledge gained indirectly from the observations of others. The knowledge that we use every day to conduct our lives and professions traces to these two sources. When the subject is narrowed to a field of scientific inquiry, individuals may possess knowledge from the first category when they are the researchers who have investigated phenomena using the scientific method. The information that they possess in matters that they have not directly investigated was acquired from others, who have related it to them verbally or by writing.
Scientists are also dependent on the same sources of information for most of what they know. They must determine what data and what interpretation is to be believed and what should be rejected. The mechanisms available to us all for such filtering include scientific peer review, repeatability of measurements, accuracy and control of data acquisition, and the integrity of the reporting scientist.
In the real world scientists must place a great deal of weight on the earned respect of investigators who are looked to as experts. Such individuals are the very basis of the level of understanding we possess as a collective group. When we have a number of recognized experts reaching similar conclusions concerning the meaning of collected data, there is good reason to believe that their concurrence is meaningful. When a fingerprint is used as evidence in a court, there will be a fingerprint expert who will testify that the print belongs to a specific person. The jury can believe it or reject it, but they are unlikely to be able to individually make the determination themselves.
When one of us wants to learn something, we generally seek out the information that has been compiled in text books and journals. If we read enough of it, we will learn which individuals are regarded by their peers as the real experts in the field. We will also find situations in which there is disagreement among people who are working on related matters and we can ultimately discover why they disagree and where they are in agreement. We may be left with a belief that some issues are not resolved and that others are not in dispute by the most knowledgable people on that subject. This is the normal state of affairs in just about any discipline.
When scientists use evidence to support their work or their interpretation of something, they are careful to identify the experts who they wish to reference and would expect that failure to do so would brand their references as worthless. Why? Well, someone may decide to offer the words of a literary editor on a scientific subject, or to bring in views of someone known to have an ax to grind and has a reputation of attempting to intentionally mislead the public.