"By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning"

This quote by Michael Behe is describing the principle of irreducible complexity. This idea specifies that particular biological systems are too complicated to have evolved from easier, ancestral types. These systems are made up of numerous well-matched, interacting parts that add to the fundamental function of the system. If any one of these parts is eliminated, the system will no longer have the ability to function. This concept is used to refute the theory of development, as it recommends that specific biological systems could not have actually progressed from simpler kinds. It is likewise utilized to support the idea of smart design, as it recommends that these complex systems need to have been created by an intelligent being.