15 Beliefs From History That Were Considered “Science”

Science has not always meant what it means today. Throughout history, many ideas once labeled as scientific were based on limited evidence, cultural beliefs, or pure speculation. While these theories often guided medicine, astronomy, and human behavior, many have since been debunked or completely discarded. Looking back, it offers a fascinating view of how human understanding has evolved and how science is shaped by the times.

1. 1. The Four Humors

Ancient Greek medicine was built around the idea that the body contained four fluids: blood, phlegm, yellow bile, and black bile. It was believed that health depended on maintaining a balance among these humors. Imbalances were thought to cause both physical illness and emotional states. Treatments included bloodletting, vomiting, and diet adjustments. This theory dominated Western medicine for nearly two thousand years.

2. 2. Geocentrism

For centuries, it was widely believed that the Earth was the center of the universe. This view was supported by philosophers like Aristotle and Ptolemy and endorsed by religious authorities. The model explained planetary motion through a system of rotating spheres. It wasn’t until Copernicus, Galileo, and Kepler challenged it that the heliocentric model gained ground. Geocentrism was eventually abandoned as astronomical tools advanced.

3. 3. Spontaneous Generation

This belief claimed that life could arise from non-living matter, like flies emerging from rotting meat. The idea seemed reasonable in an era with a limited understanding of biology. It was accepted as scientific truth until Redi and Pasteur conducted experiments that proved otherwise. Their work showed that life comes only from existing life. Spontaneous generation was fully discredited by the late 1800s.

4. 4. Phrenology

Phrenologists believed that the shape and bumps of a person’s skull revealed their personality and intelligence. This theory gained popularity in the 19th century and was used in both medicine and law. Charts were made linking skull regions to character traits like courage, laziness, or kindness. Although widely accepted at the time, it lacked scientific evidence. Phrenology is now viewed as a pseudoscience with dangerous social implications.

5. 5. Miasma Theory

Before germ theory, diseases like cholera and the plague were thought to spread through “bad air” or mists called miasmas. This belief shaped public health efforts, including the design of cities and hospitals. People burned herbs and wore masks to filter the air. While it led to cleaner environments, it failed to address the real causes of disease. Germ theory eventually replaced miasma theory in the late 19th century.

6. 6. Flat Earth Theory

Although early civilizations had evidence of a spherical Earth, the flat Earth belief persisted in some cultures and resurfaced at various points in history. It claimed that the Earth was a flat disk, sometimes covered by a dome. Navigation and astronomy eventually disproved it through consistent observations. Photos from space later provided undeniable visual evidence. Despite this, small groups still promote it today.

7. 7. Alchemy

Alchemy combined elements of science, philosophy, and mysticism, aiming to transform base metals into gold and discover immortality. It was practiced across Europe, Asia, and the Middle East. While based on flawed ideas, it laid the groundwork for modern chemistry through experimentation. Alchemists developed tools and methods still used today. Eventually, it was replaced by more accurate chemical science.

8. 8. Hysteria in Women

For centuries, doctors diagnosed women with “hysteria” for symptoms ranging from anxiety to fainting. The term was based on the Greek word for uterus and blamed many female issues on a “wandering womb.” Treatments ranged from herbal remedies to institutionalization. This diagnosis was used to dismiss and control women’s health concerns. Modern medicine recognizes these symptoms as legitimate and unrelated to gendered myths.

9. 9. Earth-Centered Universe with Crystal Spheres

Ancient astronomers once believed that the planets and stars were embedded in invisible crystal spheres rotating around the Earth. This model explained celestial movement through perfect circles and divine harmony. It fit neatly with religious views of the universe. As observations grew more precise, this theory could no longer account for planetary paths. It was eventually discarded in favor of elliptical orbits and gravity-based models.

10. 10. Vitalism

Vitalism suggested that living organisms were fundamentally different from non-living things due to a “vital force.” Scientists believed that life could not be explained by physics or chemistry alone. This idea influenced biology and medicine for centuries. Once organic compounds were synthesized in laboratories, vitalism began to lose support. It is now considered obsolete in modern science.

11. 11. Bleeding as a Universal Cure

Bloodletting was believed to treat nearly every illness by removing “bad blood.” Doctors used leeches, blades, and cupping to draw blood from patients. The practice persisted into the 19th century, despite questionable results. It was often harmful and weakened already sick patients. Scientific research later showed that most diseases are unrelated to blood volume.

12. 12. Racial Science

In the 18th and 19th centuries, some scientists attempted to categorize humans into racial hierarchies based on skull size and physical traits. These ideas were used to justify colonialism, slavery, and discrimination. They were presented as objective science despite lacking credible evidence. Modern genetics has completely discredited these claims. Today, racial science is regarded as unethical and unscientific.

13. 13. Astrology as a Scientific Tool

Astrology was once deeply intertwined with astronomy and medicine. Ancient scientists used star charts to make predictions about health, weather, and human behavior. It was considered a serious field of study alongside mathematics and natural science. Over time, astrology was separated from evidence-based astronomy. While still popular in culture, it is no longer viewed as science.

14. 14. Hollow Earth Theory

Some early thinkers proposed that Earth was hollow and possibly contained entire civilizations inside. It was taken seriously enough to inspire expeditions and books. The idea was rooted in mythology and speculative geography. As geological understanding improved, the theory was disproved by seismic and drilling data. It is now seen as a fringe belief rather than a scientific idea.

15. 15. Cold Fusion (1989 Claim)

Two scientists announced they had achieved cold fusion, a form of nuclear reaction at room temperature. The claim made headlines and promised unlimited clean energy. However, other labs could not replicate the results. The original experiment was found to be flawed, and funding was withdrawn. Cold fusion remains a controversial topic in scientific circles.

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• pseudoscience
• history
• Myths
• Science
• Beliefs