New research provides additional evidence that political ideology can interfere with logical reasoning. The findings were published in the scientific journal Thinking & Reasoningshed light on how politically motivated reasoning affects the ability to correctly evaluate reasoning.
Argument is a type of logical argument that applies inductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true. (“All men are mortal. Socrates is a man. Therefore Socrates is mortal.”) Arguments can be valid or invalid, depending on whether the conclusion follows logically from the premises. Importantly, the validity of an argument depends on the form of the argument, not on the truth of the premises.
“I’ve always been interested in the psychology behind political opinions and how people judge whether a politically charged statement is true or false. “The study of the ability to identify logically valid conclusions in policy matters appeared particularly important in the supposed post-truth world we live in,” explained study author Julie Aspernäs, PhD at Linköping University in Sweden.
The new study included a nationally representative sample of 1,005 Swedish adults. Participants first completed a short training session to familiarize themselves with the reasoning. They were then shown a series of reasonings and asked to indicate whether the conclusion followed logically from the premises. Participants were explicitly instructed to ignore any beliefs about the content of the reasoning and to focus only on whether the argument was logically valid.
The reasoning contained both non-political and political arguments. Non-political reasoning included statements such as “If knthzor has two legs, then knthzor cannot join the Umpt. Knthzor cannot join Umpt. Therefore knthzor has two legs. Political reasoning included statements such as “If the labor market is not fair, then the state should intervene to equalize incomes. The labor market is not fair. Therefore, the state should intervene to equalize incomes.”
Reasonings differed in logical validity (valid or invalid), difficulty, and ideology (left or left inference). system, gender neutral education, multiculturalism, military defence, refugee asylum and climate change.
The researchers found that participants tended to demonstrate better accuracy in evaluating reasoning when there was a match between the validity of the reasoning and the ideological position of the conclusion. Left-handed participants performed worse on reasoning where the correct answer was not aligned with left-wing ideology, while right-handed participants performed worse when the correct answer was not aligned with right-wing ideology.
The findings suggest “that your judgment is likely to be tainted by the desire to believe what you want to believe,” Aspernäs told PsyPost. “Many of us would benefit from a greater ability to detect conclusions based on flawed reasoning.”
The results are consistent with a previous study, published in 2020, which found that people were more willing to accept logical conclusions that were consistent with their political beliefs compared to conclusions that were inconsistent.
Furthermore, another study published in 2019 provided evidence that the ability to evaluate logical arguments was affected by people’s political views. “Liberals were better at spotting flawed arguments supporting conservative beliefs, and conservatives were better at spotting flawed arguments supporting liberal beliefs,” explained Anup Gampa of the University of Virginia, lead co-author of the study.
Aspernäs noted that ideology appears to interfere with logical reasoning regardless of whether a person holds right-wing or left-wing beliefs. “I would like to emphasize that we have found faulty reasoning on both sides of the political spectrum, and that most of us engage in motivated reasoning from time to time, albeit to varying degrees,” he said.
The study, “Motivated Formal Reasoning: Ideological Belief Bias in Deliberative Reasoning on Various Political Issues,” was authored by Julia Aspernäs, Arvid Erlandsson, and Artur Nilsson.