If you mention the phrase "scientific theory" during a debate with someone who is fairly ignorant regarding matters of science, they will almost always focus upon the term "theory" as if this suggests the concept is just someones opinion. It doesn't matter if you are speaking about the theory of relativity, gravitational theory, the theory of evolution, climate change theory, atomic theory, or yes even the germ theory of disease - as soon as the term theory is heard, people come out of the woodwork to claim these theories are not fact because if a concept was able to be proven it would no longer be considered to be merely a theory.
Because of this, it is probably a good idea to explain what a scientific theory actually is. Per the United States National Academy of Sciences, scientific theory can be described as follows:
In everyday usage, “theory” often refers to a hunch or a speculation. When people say, “I have a theory about why that happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence.
The formal scientific definition of theory is quite different from the everyday meaning of the word. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence.
Many scientific theories are so well established that no new evidence is likely to alter them substantially. For example, no new evidence will demonstrate that the Earth does not orbit around the Sun (heliocentric theory), or that living things are not made of cells (cell theory), that matter is not composed of atoms, or that the surface of the Earth is not divided into solid plates that have moved over geological timescales (the theory of plate tectonics). Like these other foundational scientific theories, the theory of evolution is supported by so many observations and confirming experiments that scientists are confident that the basic components of the theory will not be overturned by new evidence. However, like all scientific theories, the theory of evolution is subject to continuing refinement as new areas of science emerge or as new technologies enable observations and experiments that were not possible previously.In this respect it seems clear why many scientific theories can never be considered scientific fact because the areas of study are constantly evolving and research is ongoing. We may never fully understand gravitational theory, but we do know how an object will react if we toss it into the air.
Similarly, the American Association for the Advancement of Science has stated the following surrounding scientific theory:
Scientists strive to make sense of observations of phenomena by constructing explanations for them that use, or are consistent with, currently accepted scientific principles. Such explanations—theories—may be either sweeping or restricted, but they must be logically sound and incorporate a significant body of scientifically valid observations. The credibility of scientific theories often comes from their ability to show relationships among phenomena that previously seemed unrelated.In fact, scientific theory "are the most reliable, most rigorous, and most comprehensive form" of scientific knowledge that humans possess. Scientists aren't treating these theories as hypotheses nor are they considering them to be nothing more than educated guesses. Scientific theories require specific criteria to be met including the requirement that the theory be well supported by independent strands of evidence rather that by one lone source and that the theory be makes falsifiable predictions with consistent accuracy.
Thus with this in mind, one can only shake their head in disbelief when someone proclaims that they don't accept a mutually accepted scientific theory. Believe it or not there are those among us who deny that the Earth revolves around the Sun (heliocentrism), just as there are those among us who deny that an apple will fall from a tree and strike the ground beneath it (gravity). In most cases these people are simply ignored because most people have accepted these theories as scientific fact.
However in some cases, due in no small part to simply ignorance of the subject matter and/or ignorance to the entire concept of microbiology, you find people who deny that microbes cause disease (germ theory), and they often choose to travel back in time to the 1800s as they attempt to rewrite history to proclaim that Louis Pasteur's germ theory was a sham and that Antoine Béchamp's theory was the correct one.
Obviously much has been written about germ theory, but the simple version is Pasteur believed the microbe caused the disease while Béchamp believed the disease caused the microbe. Béchamp simply did not accept the belief that bacteria could create disease in a host and instead he felt the disease would in turn produce the bacteria which could then be detected.
In the 1800s there was room for debate, because they lacked many of the tools and techniques afforded the modern day scientist, and even though Béchamp's theories rendered him to the shadows of obscurity, with modern methods science has shown Pasteur's theory to be the correct one. The book is closed, the jury has ruled, the facts are in, and surely nobody would bother to challenge accepted scientific theory right?
In fact, there are those on the lunatic fringe who do exactly that. Many anti-vaccinationists have latched on to the idea that Béchamp's germ theory is the correct one whereas Pasteur was wrong all along. If there was any doubt, Lowell Hubbs is one of these people... because where would a great medical or scientific conspiracy be without our good friend Mr. Hubbs.
Don't bother asking these people how diseases are spread from person to person because if you don’t believe in the accepted germ theory, and if the bacteria are caused by the disease itself, how exactly would it be transmitted to another host? Perhaps even more curious is how a simple cut on one's finger could become infected if it were not for the transmission of bacteria?
If these germ theory denialists are to be believed, then antibiotics shouldn't actually help treat or cure any disease, because they would simply attack the microbe itself and never touch the underlying condition which was producing the microbe. So how exactly can they describe antibiotics or antibacterial agents?
How does a germ theory denialist explain how entire groups of people become sick by eating tainted tomatoes or spinach. The whole thing makes me wonder if these people head to Central America on vacation and dare to drink the water. Hey... if microbes are a symptom rather than a root cause, what is there to be afraid of?
I challenge any germ theory denier, including but not limited to Lowell Hubbs, to listen to the following video and not come away with it questioning their silly ideas.
Ahhh... who am I kidding? We all know anyone who denies the most basic scientific premise is not likely to use logic as part of their thought process.