Evidence is a piece of information that may or may not help constitute proof. For example, a video of someone running away from a bank that has been robbed constitutes evidence, but may not end up proving anything. The person could later be shown to have been running toward a toddler in danger of walking in front of a car.
Proof is demonstrated when a set of circumstantial evidence and testimony (as well as certain kinds of logical demonstrations) converge on a single interpretation. Of course, in the world of science, absolute proof of anything is rare. Thus, we will often focus on what line must be crossed in order to move from coincidence to proof.
What is it that “flips the switch” inside someone’s head to persuade them that one side of a question is more persuasive than another? Not absolutely proven, but more persuasive, especially in cases where each piece so-called evidence can be declared a coincidence?
Circumstantial evidence is often regarded as more powerful and persuasive than the testimony of a single eyewitness. For example, in criminal cases, if the circumstantial case (composed of a so-called coincidences) is powerful, it can overcome a single eyewitness.
— Suppose you tell jurors that a man is a murderer and you have one bit of evidence: The suspect is known to have worn Ferrigamo shoes, and the suspect wears Ferrigamo shoes. Of course, they would look at you funny.
— Suppose you tell jurors that a man is a murderer and you have one bit of evidence: The suspect was seen to be thin and tall, with long red hair. You say that the suspect is thin and tall, with long red hair. Again, they would not be convinced.
— Suppose you tell jurors that a man is a murderer and you have one bit of evidence: The suspect is known to have left the scene in a white ’65 Mustang with bald tires. They would still not be convinced, based on a single piece of evidence. It still could be a coincidence, because many people may fit that criterion.
But supposed you told the jurors that the murderer wore Ferrigamo shoes, was tall and thin with red hair, and drove a white ’65 Mustang with bald tires, and the suspect fits all of these criteria. Now you would have a case and have reason to ferret out more evidence.
Because circumstantial evidence is so persuasive when properly applied, others must find ways to weaken the circumstantial case. They do this by dividing up the coincidences and emphasizing the fact that there are only coincidences, attempting to keep people from seeing them all put together.
Circumstantial evidence works like the Pointillist painters did, someone like Seurat:
Is this dot on the canvas the image? No. How about this dot? No. How about this dot? No.
But once you have enough dots, the image emerges, and only someone with an agenda tries to argue against the obvious pattern that is forming.
Those who argue against a strong set of circumstantial evidence are like the defense team for the Rodney King police brutality trial. The defense lawyers tried to keep the jurors from applying the entire videotape of the beating. Instead, they slowed it down frame by frame, showing each officer swinging a baton and asking, “Is this single hit police brutality? No? How about this one? No? How about this one?” and so on.
When viewing circumstantial evidence, think in terms of the stronger case versus the weaker case. Beware of those who demand absolute proof. There is rarely any such thing.
This distinction is important, and the critical principle it embodies illuminates the differing methods of argument that lawyers, academics, reporters, and others bring to bear on various debates.
There are, essentially, two classes of advocates:
— On the one hand, advocates of absolutism who take a position, claim that it stands by default, and then advise that only absolute and convincing proof of the contrary will dissuade them from their position.
— On the other, advocates of relative merits who take no initial stand, weigh the relative strengths of competing arguments, and acknowledge when, in terms of reason and evidence, one argument or position is stronger than another, even when the stronger argument stands against the position they happen to favor.
The advocates of absolutism, when standing by a weaker position, tend to ignore those arguments that expose their own weaknesses and whenever possible, shift the focus to minor points that are only marginally relevant to the argument itself.
Such tactics include simply “forgetting” to mention the strongest of an opponent’s arguments, piling one red herring on another (overemphasizing lists of trivial data, for example), and discrediting circumstantial data (since each item can be isolated and dismissed as coincidence, without taking into account a mass of “coincidences” that tell a compelling story).
Beware of those who easily dismiss a pile of circumstantial evidence. Such evidence is what drives the scientific method.
Partially adapted from my peer-reviewed article, “Shakespeare’s Knowledge of Law: A Journey through the History of the Argument.”