Doubt at all Costs

Doubt At All Costs

For Aristotle, truth is not a popularity contest or a success story. In what we now call the Metaphysics, he ties truth to reality itself, not to what seems persuasive, coherent, or useful.

“...to say of what is that it is, and of what is not that it is not ...”

Truth and falsity, Aristotle says, do not belong to isolated words by themselves. They appear when the mind, or speech, combines and separates things correctly. In other words, truth belongs to judgement and assertion. That matters for archaeologists, historians, journalists, police investigators, fact-checkers, and forensic scientists. The past is not infinitely elastic. Something happened, and that thing is the truth. But gaining access to it is harder than it seems.

As investigators, we are not handed the truth directly. None of us has it in full. What happened is not directly available to us. We approach it through traces, fragments, texts, images, echoes, smells, digital footprints, datasets, and metadata. We piece these together to reconstruct what happened in our absence. By examining what remains, we infer what we did not witness.

An image may point us to a location and a certain date/time. At that location, we may find fingerprints. From those fingerprints, we may corroborate the identity and the likely activity of the person in the image. Through this exercise, we bring answers: What happened? Where? When? And who? 

But conclusions like these are not as certain as strict deductions. They may be well supported, sometimes very strongly, but as David Hume reminds us, the opposite remains logically possible.

“The contrary of every matter of fact is still possible.”

Where Hume warns us against being too certain, Charles Sanders Peirce offers a practical way of moving closer to the truth: develop a hypothesis that explains what you observe. Ask what event would favour finding these clues. From there, the hypothesis has to be tested, challenged with alternatives, and revised based on what may have appeared as facts. A hypothesis is something to test, not something to fall in love with.

Duhem and Quine teach us that a good explanation is not necessarily the only explanation. The same evidence can support several different stories about what happened. The image may have shown a similar-looking but different place. A fingerprint found in real life is often partial or unclear. The lower its quality, the greater the chance of attributing it to the wrong person. And even if the identification result is sound, the object carrying the print may have been moved to the scene later, misleading us about the person’s presence or actions.

Rather than asking whether their observations fit the scenario they already have in mind, serious investigators ask how the evidence behaves across competing hypotheses. How well does this evidence fit this explanation, compared with its alternatives? Observations become more valuable when they shift the balance between those alternatives. That is the move from storytelling to inquiry.

Once that is understood, probabilistic reasoning follows naturally. Absolute certainty becomes rare, if it was ever there to begin with. It may be more probable to observe this fingerprint if the suspect were present than if he were not. That is the basic logic of probabilistic interpretation in forensic science. It is often performed by asking how much more the findings support one proposition than another, not by claiming that the findings settle the whole case.

This affects the way results should be reported. A trace may be rare. A match may be strong. This reinforces the evidential value but does not make the conclusion certain. The experts’ job is to report the strength of their findings under stated propositions, not the final truth. 

This way of reporting respects the concept of fallibilism. A conclusion may be justified without being conclusive. We may have strong grounds for an interpretation without being entitled to present it as final.

So “doubt at all costs” is not hesitation, and it is not indecision. It is a way of keeping conclusions proportionate to the evidence, in context.