An AI analysis finds that since the 1970s, speeches by US Congress members have shifted to favour language such as “fake news” and “mislead” over words such as “science” and “statistics”
By Jeremy Hsu
10 April 2025
Congressional speeches have shifted to become less evidence-based
Volodymyr Tverdokhlib/Alamy
The language that elected members of the US Congress use in debate increasingly includes words such as “phony” and “doubt” over words such as “proof” and “reason”.
This linguistic trend away from evidence in favour of intuition was revealed in an artificial intelligence analysis of millions of congressional speech transcripts. It also coincides with both greater political polarisation in Congress and a decline in the number of laws that get enacted through Congress, says Stephan Lewandowsky at the University of Bristol in the UK.
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“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’,” says Lewandowsky. “Those notions of honesty and truth are expressed in how we use everyday language.”
Adapting an off-the-shelf AI language model, Lewandowsky and his colleagues analysed the words used in transcripts of 8 million congressional speeches given between 1879 and 2022. They compared the congressional text wording with representative groups of 49 evidence-based keywords such as “logic” and “reason” and 35 intuition-based keywords such as “suspicion” and “gut.” They then computed a score showing if a given congressional speech leaned toward evidence or intuition.
They found that Congress has increasingly favoured intuition-based language over evidence-based language since the 1970s. Before then, intuition-based language also spiked in speeches made during the Gilded Age in the years 1899 to 1901 and the Great Depression in the years 1933 to 1935.