US congressional speeches are getting less evidence-based over time

An analysis of language used in speeches by elected members of the US Congress has revealed a shift towards the use of words like “phony” and “doubt” over words such as “proof” and “reason”. This trend, indicating a move away from evidence-based arguments towards intuition, was uncovered through an artificial intelligence examination of millions of congressional speech transcripts. According to Stephan Lewandowsky from the University of Bristol, this linguistic shift aligns with increased political polarization and a decrease in the number of laws enacted through Congress.

Discussing the implications of this trend, Lewandowsky notes, “We can think that truth is something we can achieve based on analysis of evidence, or we can think of it as the result of intuition or ‘gut feeling’. Those notions of honesty and truth are expressed in how we use everyday language.”

By utilizing an AI language model, Lewandowsky and his team analyzed 8 million congressional speeches dating back to 1879. They compared the usage of evidence-based keywords like “logic” and “reason” with intuition-based keywords such as “suspicion” and “gut”, generating a score to determine the leaning of a speech towards evidence or intuition.

Their findings indicate a growing preference for intuition-based language in Congress since the 1970s, with previous spikes during the Gilded Age and the Great Depression. John Jost from New York University suggests that this shift reflects rising anti-intellectualism, populism, and a disregard for scientific expertise in recent years.

Commenting on the research methodology, Renáta Németh from Eötvös Loránd University appreciates the in-depth analysis of word context, capturing subtle associations and cultural meanings. Moving forward, Lewandowsky plans to investigate similar language trends among individual lawmakers in congressional speeches and social media posts, as well as comparing trends across different historical parliaments.