Why was Lamarck’s theory of evolution rejected by many scientists during his lifetime?

During his lifetime, Jean-Baptiste Lamarck’s theory of evolution was generally rejected by the scientific community as implausible, unsubstantiated, or heretical.1

While Lamarck was a respected systematist, his comprehensive theory of organic transformation—which proposed that species evolved through a combination of an inherent "power of life" toward complexity and the inheritance of characters acquired through environmental influence—faced significant skepticism. Scientists of his day found his ideas lacked sufficient empirical evidence and did not align with the prevailing understanding of biological processes.1

Furthermore, the scientific climate of the era was not receptive to his radical notions of species mutability. Although Lamarck was the first to present a detailed, systematic theory of organic evolution, it was not until later in the 19th century that evolutionary theory gained broader scientific traction, primarily through the work of Charles Darwin and the subsequent development of natural selection. Lamarck's specific mechanism—the inheritance of acquired characteristics—was eventually discredited in the 20th century as experimental evidence failed to support it and modern genetics provided a different explanation for heredity.123