Following the Scientific Consensus Is the ‘Least Wrong’ Line of Thought

All scientific theories, at their core, contain some elements of incorrectness. This is why achieving consensus is crucial.

Two terms that carry distinct meanings in scientific discourse compared to everyday usage are "theory" and "consensus." In casual conversation, a theory often suggests a high level of uncertainty. It can refer to any idea or guess—no matter how unfounded—that can be labeled as a theory, similar to how both the concept of gravity and the belief in a flat Earth fall under the same umbrella.

While many recognize the difference between scientific and colloquial uses of "theory," the distinction becomes even less clear with "consensus." In general usage, consensus implies that a majority holds a certain belief, but this does not guarantee its correctness. For example, consensus can just as easily apply to claims like "the Earth is warming" as it can to "ninjas are cooler than pirates."

However, when scientists refer to consensus, they mean the most reliable approximation of reality, backed by extensive evidence and the agreement of the majority of professionals in a particular field. Understanding how adhering to scientific consensus benefits us and how rejecting it can be detrimental is essential.

Theory: This concept is foundational. To grasp what it means to acknowledge or confront the scientific consensus on an issue, we must revisit the definition of a theory.

I am not referring to the everyday definition, which encompasses any proposed explanation for why an event took place (e.g., flat Earth theory).

Nor am I discussing the mathematical definition, which is a self-consistent set of postulates that form a framework (e.g., string theory).

Additionally, I’m not speaking of speculative extensions of mainstream theories that lack sufficient supporting evidence (e.g., supersymmetry theory).

Lastly, I am not addressing an idea that was once valid but later contradicted by significant evidence (e.g., Lamarckian evolution).

Instead, when scientists frequently discuss theories, they refer to those that are robustly supported by evidence—the foundation of modern science. For instance, General Relativity is our theory of gravity, the Standard Model explains elementary particles, and Darwinian evolution alongside genetics elucidates how traits are inherited. When scientists mention a theory, they are typically referencing well-established frameworks guiding current and future discourse.

The Novel Phenomenon: Concepts like "scientific consensus" arise in contexts where new, significant, or unexpected observations occur.

We observe an increase in atmospheric carbon dioxide levels, global ocean acidification, and a rise in extreme temperature events worldwide.

We have noted that a cosmic event happened approximately 130 million light-years away, with gravitational waves arriving slightly before the first electromagnetic signals—by 1.7 seconds.

We also witness the emergence of a new disease in humans, with a genetic sequence that, while related, is evolutionarily distinct from known pathogens.

Although these examples span various scientific disciplines—from climate science to astrophysics and virology—scientists adopt a consistent methodology across all fields.

Identifying the Null Hypothesis: This is an implicit step recognized by scientists but often overlooked by non-scientists. The null hypothesis refers to the explanation that suggests the new phenomenon can be accounted for by existing laws, theories, and frameworks.

The null hypothesis posits that while a new phenomenon has been discovered, it does not necessitate the introduction of new rules or factors.

It often indicates that observed behaviors are simply variations within natural limits. Many discoveries that were initially deemed groundbreaking were later re-evaluated as statistical anomalies when further data was collected. Ruling out the null hypothesis can be a significant achievement; for instance, the Earth's temperature data from as early as the 1880s has shown a high level of confidence that human activities contribute to warming.

So, We’ve Found Something New. Now What?: Scientists often ask themselves a crucial question when a novel phenomenon emerges and is considered non-controversial.

The Earth is warming, oceans are acidifying, and carbon dioxide levels are climbing.

Gravitational waves and electromagnetic signals have been accurately timed, confirming they originated from the same event, yet the gravitational waves arrived 1.7 seconds earlier, suggesting different interactions with matter.

SARS-CoV-2 indeed appeared in humans in late 2019, though its exact origin remains unclear.

In such cases, scientists often refer to the default hypothesis: the premise that existing knowledge is sufficient to explain the emerging phenomenon, requiring only accurate identification of the key factors involved.

Identifying What Matters: Many believe that science is resistant to new ideas, clinging to established knowledge.

In truth, while some may hold such views, the reality is that established scientific understanding serves as a strong foundation for accommodating new phenomena.

The default hypothesis usually posits that mundane explanations exist for novel observations, relying on the effective application of existing scientific principles. This hypothesis is the least radical assumption: that additional components may be required for a complete understanding, but that existing scientific rules are sufficient to explain all observations.

Recognizing Alternatives for What They Are: Novel rules may sometimes emerge, and unexplained observations can signal the need for adjustments to our theoretical frameworks. However, elevating alternative explanations to primary status necessitates evidence that the default hypothesis is inadequate.

Historical examples illustrate this well:

• Mercury's orbit inconsistencies led to the hypothesis of an unseen planet, Vulcan, which was later dismissed, paving the way for the validation of General Relativity.
• The geological age of the Earth conflicted with the Sun's energy output, requiring breakthroughs in nuclear physics to explain solar longevity.
• Observations of galaxies moving at unexpected speeds prompted the concept of "dark matter," which was only accepted after extensive evidence ruled out normal matter explanations.

Such instances are exceptional; more often, the default hypothesis prevails. Scientists must remain open to alternative explanations for any observed phenomena but should consider them speculative and unproven until the default hypothesis is shown to be inadequate.

• The default hypothesis states that the Earth's warming, climate changes, and ocean acidification are largely due to human influence, primarily through fossil fuel combustion.
• The default hypothesis explains the timing discrepancy between gravitational and electromagnetic signals as a result of light traveling through matter, which slows it down, while gravitational waves pass unaffected.
• The default hypothesis posits that SARS-CoV-2 entered the human population through zoonotic spillover, likely linked to human encroachment on wildlife habitats.

Consensus: Once we have thoroughly researched a scientific issue, akin to what leading scientists do, the next critical step is to synthesize our findings to achieve a scientific consensus.

What does this entail?

A scientific consensus requires:

• A cohesive framework that addresses both longstanding puzzles and new phenomena.
• No unverified conjectures must hold true for the explanation to be valid.
• A thorough review of scientifically admissible evidence reveals no unresolved critical issues.
• The overwhelming majority of professionals in the field arrive at the same conclusion, agreeing on the best explanation for the observed data.

Any consensus we reach is always provisional; any alternative could ultimately prove correct. However, to effectively contest a consensus—such as the Standard Model, dark matter, cosmic inflation, Darwinian evolution, human-driven climate change, or the natural emergence of SARS-CoV-2—one must pinpoint where the consensus falters and demonstrate that the preferred alternative not only succeeds where the consensus does but also excels in areas where the consensus is already validated.

Historically, scientific consensus has been re-evaluated and often found lacking in some aspects. When this occurs, the "old consensus" doesn't become incorrect but rather is reframed as a particular case within a broader, more accurate framework—a new scientific consensus. Current scientific consensus is not indicative of groupthink; instead, it reflects our best approximation of reality, derived from extensive evidence and the most successful scientific theories available.

As science progresses, it is likely that many existing consensus views will be reconsidered, just as Newtonian gravity was revolutionary, accurate under certain conditions, yet ultimately an approximation of deeper truths. This is not a flaw in scientific inquiry; it is the essence of science.

By interrogating the Universe with precision, we may uncover deeper truths. The key to progress lies in understanding the limitations of current consensus and the criteria needed to challenge it. If one is not actively doing this when considering alternatives, they are contesting the public's notion of consensus rather than the scientific understanding of it.

Starts With A Bang is authored by Ethan Siegel, Ph.D., writer of Beyond The Galaxy and Treknology: The Science of Star Trek from Tricorders to Warp Drive.