You know you have been successful as a scientist when a phrase of your invention works its way from the academy into public usage. Nowadays, we all unselfconsciously use phrases that originated in scientific journals, like “placebo effect”, “acid test”, and “confirmation bias”. The lattermost of these phrases, also known as “my-side bias”, has become increasingly widespread in recent years.

Confirmation bias is when we seek out information which supports our viewpoint while ignoring or giving less weight to contradictory information. It explains how we tend to become entrenched in our opinions over time. Even if your “media diet” consists of perspectives from both sides of the political aisle, you will still give more weight to evidence from the side which supports the position you already have. When it comes to politics, even a balanced diet will not guarantee healthy thinking.

“When it comes to politics, even a balanced diet will not guarantee healthy thinking.”

A recent study published in the Journal of Cognitive Psychology found that “my-side bias” applies not just to facts and opinions, but to the process of reasoning itself. Focusing on the ever-touchy topic of abortion, the team of researchers behind this paper tested people’s ability to assess the logic of various pro and con arguments. To get a baseline for logical reasoning ability, participants were first asked to evaluate the logical validity of a neutral syllogism such as: i) All mastiffs are dogs. ii) Some dogs are black. iii) Therefore some of the things that are black are mastiffs. This is an invalid syllogism, as the final statement does not necessarily follow from the first two. In this case, it is possible that none of the black things are mastiffs. Participants were also assessed on their ability to identify a valid neutral syllogism.

After this, participants were presented with one valid and one invalid syllogism for both pro-life and pro-choice positions. For instance, the logically invalid pro-choice syllogism was: i) All abortions are women’s rights. ii) Some of women’s rights should be supported. iii) Therefore some of the things which should be supported are abortions. This syllogism is invalid in the same way as the mastiff example above. In this case, it is possible that none of the things which should be supported are abortions. However, participants who identified as pro-choice were less capable of identifying it as being invalid than they were of identifying the invalidity of the mastiff example. The same was true of those who identified as pro-life, but for the opposite syllogism. As it turns out, we are worse at identifying fallacious reasoning when it supports our views.

“As it turns out, we are worse at identifying fallacious reasoning when it supports our views.”

A natural reaction to this study might be to say that those who took part may not have been clear on how syllogisms work. After all, it is easy to assess the logical validity of an argument which has no moral valence. It is quite a different story when, as a pro-choice person, you have to mark statements like “some of the things which should be supported are abortions” as invalid. This was exactly the point of the study, however. Those same people who reasoned effectively about morally neutral statements about mastiffs were unable able to do so for equally valid statements about which they had a moral opinion. The form stayed the same, but people had trouble seeing past the content.

Furthermore, the study found that those who had formal experience with logic actually performed worse than those without such experience. A similar effect was found in a 2013 study which asked participants to evaluate a piece of research on gun control. It found that those with greater numeracy skills were more prone to bias. In this study, when the results of the piece of research were in line with their views, they evaluated the research as being of high quality. However, when the results went against their own stance, they used their numeracy skills to discredit the findings. This is especially dispiriting given that the obvious solution to poor reasoning is more education. What else could work?

The role of intelligence on confirmation bias has also been investigated. In this case, the weight of evidence also suggests that greater intelligence provides no immunity against the effects of confirmation bias. Indeed, some researchers have proposed that more intelligent people are better at justifying and defending their positions against contradictory evidence. When it comes to our political beliefs, we act more like lawyers than scientists.

“When it comes to our political beliefs, we act more like lawyers than scientists.”

One lawyer you may be familiar with if you have spent much time browsing politics online of late, is conservative political commentator Ben Shapiro. Mr Shapiro is perhaps best-known for coining the mantra “facts don’t care about your feelings”. While this is doubtlessly true, the research on confirmation bias shows that the inverse – that your feelings don’t care about the facts – is not true. In fact, as the weight of evidence reveals, your feelings dictate the facts that you care about.

The real question, then, is not whether facts care about your feelings, but to what extent the facts you take onboard are filtered by your feelings. Furthermore, this latest study on moral reasoning shows that even given the same set of facts, people will systematically differ in their reasoning as a result of their feelings. Perhaps Mr Shapiro would do well to pay a little more attention to his feelings from time to time!

If what we want is a rational public debate, then these studies show that our common enemy is certainty. The internet has given us access to the entirety of human knowledge, and with it, the means to find support for all of our most cherished viewpoints. However, part of this knowledge is that we are natural-born lawyers, not scientists. This fact should not escape the attention of anybody who wishes to take part in public discussion. Neither should we fail to notice that it took the age of information to hammer home the truth in Socrates’ assertion that wisdom consists in being aware of the extent of your ignorance.