(source, I have to say that I don’t think that’s a correct way to describe the scientific method, but let’s not dwell on that for the moment)
Confirmation bias is the tendency of people to seek out evidence that is favorable to their original beliefs, and neglect evidence that is unfavorable. It’s a form of self-deception that we all suffer from, to a different extent, and that leads us to stick with our original beliefs rather than review them, even if a whole lot of contrary evidence is available. We just seem to be very good at ignoring it and focus on other, confirming evidence, even if the quality of this other evidence is dubious. The “stickiness” of beliefs resulting from confirmation bias is in turn an important cause of polarization of beliefs, the ”dialogue of the deaf” style of political discourse, and “gladiator politics“.
Now, why is there confirmation bias? We all value consistency in our identity and self-image, and are afraid to acknowledge mistakes, especially regarding values or facts that are and have been for decades the foundation of our identity. We want to feel good about our “original” and fundamental views and affiliations. If our views are intertwined with our group affiliations, then the elements of group pride and loyalty also promote confirmation bias and our disregard of evidence that contradicts our views. It’s then not only our views that are at stake, but also our sense of belonging and the future of our group. Suppose evidence is found that Jesus Christ could never have lived. If we, as Christians, disregard this evidence, taint it or reinterpret it, then we are able to keep feeling good about ourselves and our previous thinking – we feel like consistent human beings with reasonable thinking powers and without a strong propensity to error – but we are also able to support the continued existence of our group, and that’s important for the wellbeing not only of ourselves but of millions of people. Our pride in our belonging, our identity and reasoning powers, as well as our loyalty to the other members of our group are powerful forces that produce confirmation bias. Patriotism and nationalism can also be seen in this light.
How does this relate to freedom of speech? This human right is often justified by and grounded in the argument that the public and equal appearance of a maximum number of viewpoints and arguments for and against something enhances the quality of thinking, much like the observance of a physical object from different angles yields a better understanding and knowledge of that object. It’s the famous concept of the “marketplace of ideas” where opinions have to enter the struggle of competition, review and criticism. These opinions are then either rejected or they come out better at the other end. The same idea justifies democracy because democracies – ideally – use freedom of speech to find and test the best policies and laws. Equal participation of a maximum number of citizens should then guarantee the same market processes. (More on that here, here and here).
That, of course, is an ideal. In reality, we see that even in free societies public discourse is often – but not always – far removed from the search for truth and improved thinking that should characterize it. Confirmation bias is one of the causes of the distance between reality and ideal because it inhibits the public examination of viewpoints and arguments. Propaganda, dysfunctional media, inept institutions, group pressure, vote buying, disregard of expert views, irrational behavior, deliberate polarization etc. are other causes. But here I’ll focus on confirmation bias.
At first glance, confirmation bias seems to undermine the whole “epistemological justification” – if I may call it that – of free speech and democracy. The more information there is (thanks to free speech), the more likely that people can just pick those pieces of information that confirm their biases, and I understand the word “information” in a broad sense, not just including facts but theories and arguments as well, however “wild” they are. So freedom of speech seems to be more like a bad thing, when viewed in this light.
However, in order to know if something is really bad you have to imagine what would happen if it went away. Without freedom of speech, the appearance of new and conflicting evidence is much less likely, and hence it’s more likely that people stick to their biased and pre-existing beliefs. Freedom of speech doesn’t promote confirmation bias, but doesn’t eliminate it either. People have to do that for themselves. However, freedom of speech gives people the tools to combat confirmation bias, if they are so inclined. And therefore freedom of speech is neither invalidated nor validated by confirmation bias.