Evolutionary Theories: Creationism, Fixism, Lamarck, and Natural Selection
Evolutionary Theories
Opposing Theories to Evolution
Creationism
The arguments for creationism can be traced to Reverend William Paley’s Natural Theology. Creationism posits that the universe and its creatures were created by God. This involves the instant emergence of the universe, contrasting with the gradual modification of material elements. Paley’s watchmaker analogy suggests that the complexity of nature, like the human brain or an eagle’s eye, implies a divine creator.
Fixism
Fixism asserts that living organisms of different species share the same characteristics, with each individual biologically identical to their parents. Species have always existed in their current form, with no change over time. This view rejects the idea that individuals of a species could have ancestors of different species.
Evolutionism
Evolutionism explains undeniable facts that contradict mythical-religious explanations. It is based on the biological continuity of all living beings and the continuity of different forms of organization of matter.
Lamarck’s Theory
In his Zoological Philosophy (1809), Lamarck explained the reasons for his evolutionary explanation of nature and life. He proposed that changes in living species result from adaptation to the environment, based on two principles:
- The function creates the organ: Body organs are modified through use or disuse, creating acquired characteristics.
- The inheritance of acquired characteristics: These acquired characteristics are passed on to offspring.
Criticisms of Lamarckian Theory:
- Only genetic information is transmitted to offspring.
- The idea of organs developing to meet needs implies a final causality, which is not a valid explanation of biological phenomena.
The Theory of Evolution by Natural Selection
Two key aspects of Darwin’s Theory:
The concept of species: Darwin challenged the Aristotelian view of species as immutable entities with essential properties. Aristotle believed that everything has essential properties that define its type and accidental properties that can vary. Essential properties were considered timeless and unchangeable. This classification system faced challenges with intermediate creatures and the discovery of fossils.
Darwin proposed that species are not eternal and immutable but have evolved over time. This idea directly contradicted the Aristotelian tradition.