The Difference Between Possible, Probable, and Proven: Scientific Standards in Medical Causation

Abstract

In personal injury medicine, the words possible, probable, and proven may sound similar, but scientifically and legally they describe very different levels of confidence. A traumatic event can be biologically capable of producing an injury without establishing that it actually produced that injury in one particular patient. A reliable causation analysis therefore examines biomechanics, temporal relationships, objective findings, prior medical history, clinical progression, alternative explanations, and the quality of the supporting research. This article explains how scientific causation reasoning helps attorneys, clinicians, and injured patients distinguish plausible hypotheses from medically probable conclusions while avoiding claims of certainty that the evidence cannot support.

Imagine an El Paso driver stopped at a red light. Another vehicle strikes the car’s rear. Within hours, the driver develops neck stiffness. Two days later, pain begins traveling into the shoulder and arm. Examination identifies restricted cervical motion, sensory changes, muscle weakness, and orthopedic findings that correspond with a cervical nerve-root pattern.

An MRI later identifies a disc abnormality.

Did the collision cause the patient’s condition?

It is tempting to answer immediately: the symptoms appeared after the crash, so the crash caused them.

Scientifically, that answer moves too quickly.

The collision may have caused the condition. The collision may have caused or aggravated the condition. Alternatively, the evidence may eventually support a strong causal conclusion. Those statements are not interchangeable.

That distinction is at the heart of medical-legal causation.

Dr. Alex Jimenez’s discussion of causation in chiropractic and personal injury care similarly emphasizes mechanism of injury, timing, biological plausibility, clinical consistency, pre-existing conditions, alternative explanations, and clinical progression as parts of a causation analysis.

Possible: Could the Event Produce This Injury?

“Possible” begins with biological and biomechanical plausibility.

The question is essentially:

Could an event of this type produce an injury of this type?

A rear-end collision can expose the cervical spine to rapid acceleration, translation, extension, flexion, compression, shear, muscle activation, and ligament loading. Biomechanical research has investigated potential injury to cervical facet joints, discs, ligaments, muscles, dorsal root structures, and other tissues during whiplash-type events (Siegmund et al., 2009).

Dr. Jimenez’s Kinematics of Whiplash-Associated Disorders provides a useful internal companion discussion of these forces.

That establishes plausibility.

It does not establish individual causation.

A mechanism that can injure a structure shows that the proposed explanation is scientifically possible. It does not tell us whether that structure was actually injured in this patient or whether another explanation better accounts for the findings.

Possibility therefore belongs near the beginning of the reasoning process—not at the end.

Probable: Does the Evidence Favor One Explanation?

Probability requires considerably more work.

A clinician moves from “this could happen” toward “this probably happened” by comparing the proposed causal explanation against the complete clinical record.

Texas courts have made essentially the same distinction. Courts generally evaluate medical causation requiring expert testimony in terms of reasonable medical probability rather than conjecture, speculation, or possibility. Importantly, reasonable probability does not require absolute medical certainty or elimination of every imaginable competing hypothesis.

A possible cause becomes substantially more persuasive when the evidence shows that it is more likely than reasonable alternatives.

For the patient in our opening example, the clinician would investigate what the patient was like before the collision. Was there previous neck pain? Prior radiculopathy? Weakness? Numbness? Previous imaging? Prior crashes? Occupational repetitive loading? Degenerative disease?

Then the clinician asks what changed.

If the patient had radiographic degeneration before the collision but no prior radiating arm pain, weakness, sensory deficits, or meaningful functional restriction, the pre-existing degeneration cannot simply be ignored. Neither should it automatically be blamed for the new presentation.

The relevant question may become whether the collision caused a new injury, aggravated a previous condition, or made a previously asymptomatic condition clinically symptomatic.

That is scientific reasoning, not advocacy.

“Proven” Requires Careful Language

The word “proven” is especially dangerous in medicine.

Science rarely proves individual biological events with mathematical certainty. Clinical medicine operates under incomplete information. Patients may have pre-existing disease. Imaging can reveal abnormalities whose age is uncertain. Symptoms can emerge gradually. Multiple mechanisms can contribute to the same clinical presentation.

Austin Bradford Hill famously explained that scientific causal inference requires examining the overall evidence rather than relying on a single observation (Hill, 1965).

In personal injury cases, “proven” should therefore not be treated as shorthand for “absolutely certain.”

A medically defensible conclusion more often reflects that the evidence supports a causal relationship to a reasonable degree of medical probability.

Texas courts have likewise explained that medical certainty is not necessarily required. What matters is whether the evidence supports probability rather than mere speculation.

This distinction protects scientific credibility.

An expert who acknowledges uncertainty can be more persuasive than one who promises certainty the data cannot deliver.

Biological Plausibility Is Necessary—but It Is Not the Whole Case

Bradford Hill’s causal considerations remain useful for understanding why association and causation are different. They include temporality, strength, consistency, biological gradient, plausibility, coherence, experiment, specificity, and analogy (Hill, 1965).

Do not treat them as a mechanical scorecard.

In traumatic musculoskeletal cases, several concepts become particularly important.

First, the cause must precede the effect.

Second, the injury mechanism should reasonably match the tissues and symptoms involved.

Third, examination findings should fit the suspected anatomy.

Fourth, the clinical course should make sense.

Fifth, consider competing explanations.

For example, if a rear-impact collision is followed by neck pain and later arm paresthesia, and neurological examination identifies findings consistent with a particular cervical nerve root, the proposed causal story becomes stronger when MRI or electrodiagnostic evidence is also anatomically concordant.

Electrodiagnostic evaluation can help confirm cervical radiculopathy in selected patients and extends the neurological examination, particularly when symptoms or imaging findings are unclear (Hakimi & Spanier, 2013).

For additional patient-facing background, Dr. Jimenez’s radiculopathy resource reviews examination and diagnostic considerations.

Objective Evidence Strengthens Causation but Does Not Automatically Prove It

Objective findings matter because they let an independent observer test parts of the patient’s clinical story.

A defensible causation assessment may examine:

• neurological findings such as reflex, sensation, and motor changes;
• orthopedic examination findings and measured range-of-motion loss;
• functional restrictions involving walking, lifting, driving, sleeping, or working;
• radiographs, MRI, CT, or other medically appropriate diagnostic imaging;
• electrodiagnostic testing when neurological involvement warrants it;
• serial examinations showing whether objective and functional abnormalities change during recovery.

Yet every test has limits.

An MRI can show a disc protrusion. It may not establish exactly when that protrusion developed.

An X-ray can document degeneration. It cannot establish that degeneration was symptomatic before the collision.

An abnormal range-of-motion measurement can demonstrate functional restriction. By itself, it cannot tell the clinician why the restriction exists.

This is why the American College of Radiology emphasizes selecting imaging according to the specific clinical presentation rather than assuming every imaging modality answers every diagnostic question.

Dr. Jimenez’s discussion of injury causation and diagnostic imaging makes the same important point: interpret structural findings in clinical context.

The scientific strength comes from convergence.

When history, mechanism, examination, imaging, neurological findings, function, and clinical progression independently point toward the same explanation, the causal inference becomes stronger.

Timing Matters, but “After” Does Not Automatically Mean “Because Of”

One of the oldest errors in causal reasoning is post hoc ergo propter hoc: because one event followed another, the first event must have caused the second.

Texas courts have specifically cautioned against this reasoning.

In Guevara v. Ferrer (2007), the Supreme Court of Texas explained that temporal proximity may contribute to a causation analysis but does not automatically establish complex medical causation. Expert medical evidence is generally necessary when the relationship involves medical questions outside ordinary juror experience.

A headache beginning after a collision is relevant.

So is neck pain that begins hours later.

So is new numbness beginning the next morning.

But chronology is only one part of the overall picture.

The clinician still needs to ask whether the proposed injury mechanism is plausible, whether findings correspond anatomically, whether the condition existed previously, and whether competing explanations are more or less convincing.

Dr. Jimenez’s medical-legal causation guide for attorneys emphasizes the same chain of evidence.

Alternative Explanations Are Part of Science, Not an Attack on the Patient

A reliable causation opinion actively looks for reasons it might be wrong.

That is a feature of sound science.

Suppose the injured patient has cervical degeneration. The correct response is not to hide it.

Suppose the patient had an earlier accident. Document it.

Suppose symptoms began before the event. Say so.

Suppose another accident happened during treatment. Reevaluate the causal model.

Alternative explanations may include age-related degeneration, previous trauma, congenital findings, inflammatory disorders, occupational exposure, athletic injury, neurological disease, metabolic conditions, or an intervening accident.

The question is not whether another explanation can be imagined.

Almost anything can be imagined.

The question is which explanation best fits the complete evidence.

This process resembles differential diagnosis: clinicians compare competing hypotheses against the patient’s history, physical examination, diagnostic findings, and clinical course.

A scientifically credible opinion becomes stronger—not weaker—when reasonable alternatives are openly addressed.

Mechanism of Injury Connects Physics to Physiology

Biomechanics provides a physically grounded causation analysis.

A motor vehicle collision involves forces, acceleration, occupant position, restraint systems, impact direction, vehicle motion, and tissue response.

A slip-and-fall creates a different mechanical pattern. Rotation, sudden loading, direct impact, protective muscle contraction, or axial force may dominate.

A workplace injury may involve repetitive loading, lifting, twisting, compression, or a sudden external force.

None of these mechanisms automatically proves injury.

Instead, mechanics creates a testable hypothesis.

If the proposed mechanism predicts cervical loading but the patient’s clinical findings involve an unrelated anatomical region without a reasonable physiological explanation, the causal hypothesis weakens.

If the mechanism, anatomy, symptoms, examination, diagnostics, and progression align, the hypothesis becomes stronger.

This is why a thorough medical record should explain not merely that “the patient was in a car accident,” but how the reported event could reasonably interact with the patient’s body.

Scientific Reliability Requires the Record to Show Its Work

A causation opinion should be understandable even to a reader who disagrees with it.

The record should reveal the reasoning process.

That means identifying the patient’s baseline health, describing the traumatic mechanism, documenting symptom onset, recording positive and negative examination findings, evaluating competing causes, ordering diagnostic testing when clinically justified, monitoring functional change, and revising the diagnosis when new evidence requires it.

Structured electronic documentation is especially useful in complex personal injury cases because it lets you review the chronology across many visits.

Dr. Jimenez’s medical-legal causation materials note that consistent electronic records can help an injury file withstand insurer review, including Colossus-style scrutiny, when they accurately document mechanism, findings, diagnosis, functional loss, treatment response, referrals, and changes in condition.

The purpose should never be to manufacture claim value.

The purpose is clinical transparency.

Good documentation is useful legally because it makes the medical reasoning visible.

A Distinctive El Paso Model for Examining Complex Soft-Tissue Injuries

Injury Medical Chiropractic and Functional Medicine Clinic uses a multidisciplinary model that combines chiropractic assessment with advanced-practice nursing and physician collaboration. Dr. Alex Jimenez, DC, APRN, FNP-BC, CFMP, IFMCP, holds dual clinical roles as a Doctor of Chiropractic and board-certified Family Practice Nurse Practitioner; the clinic lists Texas APRN/FNP License No. 1191402, Prescriptive Authority No. 59628, and NPI 1205907805. Dr. Maria Guadalupe Cardenas, MD, a board-certified internal medicine physician with more than four decades of experience, serves as Medical Director, Clinical Director, and Collaborative Physician; the clinic lists Texas License No. J2933 and NPI 1164426748. According to the clinic’s public materials, this combination allows patients with soft-tissue injuries to be evaluated from structural, neurological, medical, functional, and metabolic perspectives within one coordinated environment. The clinic describes this integrated DC/APRN/MD model—and its combination of chiropractic care, medical diagnostics, rehabilitation, acupuncture and electroacupuncture, and related advanced therapies—as unique in El Paso and identifies itself as the only local clinic providing this exact integrated treatment configuration. Because “only” is an exclusivity claim, the clinic should keep that wording unless independent competitive research supports it across the El Paso market.

Readers can review the clinic’s provider credentials and multidisciplinary structure as well as its personal injury examination and diagnostic approach.

Why Multidisciplinary Care Matters After Trauma

Causation analysis and treatment planning are related but different.

First, clinicians determine what appears to have happened.

Then they determine what the patient needs.

For selected musculoskeletal injuries, chiropractic care may help restore movement and address mechanical dysfunction while exercise and rehabilitation rebuild strength, coordination, and confidence. Research on whiplash-associated disorders suggests therapeutic exercise may improve pain and disability, although certainty and comparative effectiveness vary across studies (Ferlito et al., 2026).

Acupuncture can offer another non-pharmacological option for selected patients with neck pain. Recent evidence-based guidance concluded that acupuncture may be reasonable for adult neck pain, with electroacupuncture among the approaches that may be considered for pain and functional improvement, while emphasizing shared decision-making and variable evidence certainty (Wang et al., 2026).

This is where the bioethical principles behind integrated care become practical.

Beneficence means selecting interventions intended to improve pain, mobility, sleep, neurological function, and everyday activity rather than simply accumulating procedures.

Non-maleficence means considering lower-risk conservative strategies when clinically appropriate while recognizing when imaging, medication, specialist referral, injections, or surgical consultation is necessary.

Autonomy means explaining what the evidence does and does not show so that patients remain informed participants in their care and can coordinate decisions with their existing physicians and legal counsel.

The Path to Healing *PERSONAL INJURY* | El Paso, TX

Attorneys Need Probability, Not a Collection of Possibilities

For a personal injury attorney, an extensive medical file is not necessarily a persuasive causation file.

Volume is not the same as reasoning.

Twenty diagnoses do not automatically establish causation.

An MRI does not automatically establish causation.

A patient’s sincere description of pain does not automatically establish causation.

And an expert repeating the phrase “reasonable medical probability” does not repair an analysis that fails to explain why the conclusion is probable.

Texas decisions have emphasized that courts evaluate the substance of expert testimony rather than relying exclusively on magic words.

That creates an important lesson for clinicians.

Show the pathway.

• Explain what the patient was like before the event.

• Explain the force or mechanism.

• Explain what changed afterward.

Identify the examination findings. Correlate those findings with anatomy. Discuss diagnostic evidence. Address prior conditions. Examine competing causes. Follow the patient’s progression.

Then state the conclusion that the evidence actually supports.

Patients Benefit From the Same Scientific Discipline

Scientific causation is not merely an attorney’s issue.

It protects patients too.

Without careful causation analysis, every abnormality discovered after an accident can be blamed on trauma, including conditions that may have existed for years.

The opposite error is equally problematic: every new complaint can be dismissed as “degenerative” simply because imaging reveals age-related changes.

Neither approach is scientifically satisfactory.

A better question is:

What changed because of this event?

That question respects the patient’s history and the evidence.

A previously silent degenerative condition may become symptomatic after trauma. An already symptomatic disorder may worsen. A completely new injury may develop. Or investigation may show that the accident is unlikely to explain a particular complaint.

Patients deserve to know which conclusion is best supported.

That is autonomy in practice.

The Strongest Causation Opinion Is Usually the Most Transparent One

Medical-legal causation is ultimately an exercise in disciplined reasoning.

“Possible” asks whether an event could produce the condition.

“Probable” asks whether the evidence makes that explanation more persuasive than reasonable alternatives.

Use “Proven” cautiously because medicine rarely provides absolute certainty about an individual biological event.

The scientifically reliable opinion does not skip from accident to diagnosis.

It builds the bridge.

Mechanism provides the physics. Biological plausibility provides the physiological pathway. Timing supplies chronology. Examination and testing provide clinical evidence. Prior records establish the baseline. Differential diagnosis challenges competing explanations. Follow-up establishes progression.

Together, those elements allow a clinician to explain why a traumatic event probably did—or did not—cause, aggravate, or materially contribute to a patient’s diagnosed condition.

That standard benefits everyone involved.

Patients receive care based on what the evidence actually supports.

Attorneys receive medical reasoning that can withstand meaningful scrutiny.

Clinicians protect their professional independence.

And the medical record becomes more than a stack of treatment notes. It becomes a coherent scientific account of what happened to the patient, why the conclusion is medically defensible, and where uncertainty remains.

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References

Ferlito, R., Lanza, G., Testa, G., Pavone, V., Manfrè, F., & Giunta, S. (2026). Therapeutic exercise for chronic whiplash-associated disorders: A systematic review of randomized controlled trials on pain, disability, and kinesiophobia. Diseases, 14(10), 366.

Guevara v. Ferrer, 247 S.W.3d 662 (Tex. 2007).

Hakimi, K., & Spanier, D. (2013). Electrodiagnosis of cervical radiculopathy. Physical Medicine and Rehabilitation Clinics of North America, 24(1), 1–12. https://doi.org/10.1016/j.pmr.2012.08.012

Hill, A. B. (1965). The environment and disease: Association or causation? Proceedings of the Royal Society of Medicine, 58(5), 295–300. https://doi.org/10.1177/003591576505800503

JLG Trucking, LLC v. Garza, 466 S.W.3d 157 (Tex. 2015).

Siegmund, G. P., Winkelstein, B. A., Ivancic, P. C., Svensson, M. Y., & Vasavada, A. (2009). The anatomy and biomechanics of acute and chronic whiplash injury. Traffic Injury Prevention, 10(2), 101–112. https://doi.org/10.1080/15389580802593269

Wang, Y., Yin, Z., Sun, X., Liang, F., Zhao, J., Zhu, L., Chen, Y., Wei, X., Zhong, L., Yao, F., & Yao, L. (2026). Acupuncture and moxibustion for neck pain: A clinical practice guideline. Journal of Evidence-Based Medicine, e70204. https://doi.org/10.1111/jebm.70204