Logical Fallacy of Affirming the Consequent / Fallacy of the Undistributed Middle Term

Affirming the consequent is a formal fallacy that covers up the problem when reasoning is based on one of the three fallacies of Agrippa's trilemma. Whenever a logical fallacy is committed, the fallacy has its roots in Agrippa's trilemma. All human thought (without Divine revelation) is based on one of three unhappy possibilities. These three possibilities are infinite regress, circular reasoning, or axiomatic thinking. This problem is known as Agrippa's trilemma. Some have claimed that only logic and math can be known without Divine revelation; however, that is not true. There is no reason to trust either logic or math without Divine revelation. Science is also limited to the pragmatic because of the weakness on human reasoning, which is known as Agrippa's trilemma.

The logical fallacy of affirming the consequent occurs in a categorical syllogism, when the middle term is not distributed. According to the rules of logic, a term is "distributed" when a sentence says something about everything the term designates. A syllogism is invalid if both middle terms are undistributed.

Major Premise: "If A then B"
Minor Premise: "B"
Conclusion: "Therefore, A" (invalid form--affirming the consequent)

Examples of the Logical Fallacy of Affirming the Consequent / Fallacy of the Undistributed Middle Term

Major Premise: "If the big bang actually took place, then we would expect to find cosmic microwave background, stars moving away from us, and the ratios of hydrogen, helium and other trace elements having a certain ratio."

Minor Premise: "We find cosmic microwave background, stars moving away from us, and the ratios of hydrogen, helium and other trace elements having the expected ratio."

Conclusion: "Therefore, big bang actually took place."

formal fallacy of affirming the consequent—and the same information can be better explained by God creating everything in 6 days and spreading out the Heavens; however, God is censored out as an explanation by fiat.

Major Premise: "If evolution were true, we would expect to find similar biochemistry in all life."

Minor Premise: "We do find similar biochemistry in all life."

Conclusion: "Therefore, evolution happened."

We would also expect to find similar biochemistry in all life if a common Creator God created all life. This is invalid form--affirming the consequent.

Major Premise: "If evolution actually happened then we would see similarities in DNA of living things."
Minor Premise: "We see similarities in DNA of living things."
Conclusion: "Therefore, evolution actually happened." (invalid form--affirming the consequent)

Major Premise: "If the Universe were billions of years old, then we would expect light from stars billions of light years away to have reached the earth."
Minor Premise: "Light from stars billions of light years away to has reached the earth."
Conclusion: "Therefore, the Universe is billions of years old." (invalid form--affirming the consequent)

Major Premise: "If the big bang had actually taken place, then we would find cosmic microwave background."
Minor Premise:  "We find cosmic microwave background."
Conclusion: "Therefore, the big bang actually took place." (invalid form--affirming the consequent)