In other threads, certain people have claimed that personal experience and testimony are not as valid as other forms of evidence. In fact, some would dismiss thousands of years and the accumulation of perhaps billions of witness/experiencer testimonies because, in their view, personal experience and testimony is not really even evidence at all.
The problem with this position is that everything one knows and or believes is gained either through (1) personal experience (and extrapolation thereof), or (2) testimony (and examination thereof), for the simple fact that if you did not experience X, the only information you can possibly have about X is from the testimony of others.
In a courtroom, for example, the entire case depends on testimony, even when there is physical evidence, because the jury relies upon the testimony of those that produce and explain what the physical evidence is, how it is relevant, and explains why it is important to the case. Unless the jurors are swabbing cheeks and conducting DNA tests themselves, the DNA evidence is in principle nothing more than the testimony of an expert witness. The jurors have no means of ascertaining the DNA “facts” for themselves; they entirely rely upon the testimony of what they assume to be a highly credible witness.
When a gun is entered into evidence, it is a meaningless fact – it’s a gun. The jurors rely entirely upon the testimony of law officers to inform them where the gun was found, if it was the right caliber, who owned it, etc. All of that information is presented through testimony.
Further, establishing motive and opportunity are forms of logical arguments, established via testimony, which counts as evidence.
Similarly, unless one is a research scientist in fields where one believes certain theories to be valid, he is (and we are as well) entirely dependent upon testimonial evidence – found in the form of research papers, books and articles written by such scientists. “Peer review” is nothing more to the reader than the testimomy of supposedly credible sources that the testimony of the authors is not blatantly false or contain factual errors.
Outside of what we personally experience, virtually all of our knowledge comes from testimony delivered via some form of media or another. We consider the source of the testimony, and the media it is delivered through, credible or non-credible to one degree or another – but that doesn’t change the fact that when we read or hear it, it is nothing more than testimony. If you are a scientist conducting research, you are personally experiencing the process and accumulation of data. Beyond that, it is only testimony to others unless they perform the same experiments. Often, the conclusions of scientific research hinge upon the testimony of other researchers, which may turn out to be fraudulent or mistaken.
So, when anyone says that testimony and personal experience are dismissible forms of evidence, they are obviously using (consciously or not) selective (and logically incoherent) hyperskepticism against an unwanted idea, because everything any of us believe or call ‘knowledge” is gained/extrapolated (hopefully using logic and logical arguments) via personal experience and/or information gained via testimony.