The Second Law of Thermodynamics

Christian Apologists often attempt to use the 2nd Law of Thermodynamics as an argument against evolution. The 2nd Law states that total entropy of an isolated system can never decrease over time, and is constant if and only if all processes are reversible. In simple terms, entropy is the randomness or disorder in a system, and is inversely related to the usable energy. So the 2nd Law demands that in a closed system, disorder can never decrease, and usable energy can never increase.

Apologists argue that evolution represents an INCREASE in order, and therefore a DECREASE in entropy. And this is a reasonable conclusion. But in spite of being reminded of this over and over again, they have willfully ignored the conditions under which the 2nd Law applies – i.e. that it is for an isolated system (a system that has no mass or energy input or output).

We know, of course, that all life on Earth takes in energy from the outside. Plants absorb sunlight, and convert it into chemical energy via photosynthesis. Animals consume plants or other animals for their energy. The result of this fact, is that the 2nd Law simply doesn’t apply to biological organisms, since they are NOT isolated systems. The entropy of the universe increases through biological processes, but that is not the case for the organisms themselves.

Ignoring the criterion for an isolated system is akin to referring to the statement that “no woman who has had a full hysterectomy can bear children”, and declaring that no woman can bear children.

The 2nd Law argument against evolution is among the absolute worst of modern apologetics. At best, it demonstrates a glaring lack of understanding of the science. At worst, it is blatantly dishonest.

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