Braghieri et al. (2025) measures news-consumption polarization (article-slant diversity), not affective polarization (in-group warmth minus out-group warmth). The 82% attribution to algorithmic exposure does not establish the framing's required causal effect on affective polarization.

[UNDERMINE → premise #0] Braghieri et al. (2025) measures polarization as the difference in article slant between Democrats and Republicans in news consumption, finding 82% attributable to algorithmic feed exposure. News-consumption polarization (diversity of article slant) is a different outcome from affective polarization (in-group warmth minus out-group warmth on feeling-thermometer scales), as operationalized in the framing. Construct validity of affective polarization measures can be compromised when using proxy outcomes; using proxy constructs can lead to type M and type S errors when studying affective polarization as a source or consequence of other variables. Therefore, Braghieri et al. (2025) measures news-consumption polarization (article-slant diversity), not affective polarization (in-group warmth minus out-group warmth). The 82% attribution to algorithmic exposure does not establish the framing's required causal effect on affective polarization. (Warrant: An effect measured on one outcome (news consumption) cannot be directly attributed to a different outcome (affective polarization) without establishing the causal transmission chain and magnitude.)

• Braghieri et al. (2025) measures polarization as the difference in article slant between Democrats and Republicans in news consumption, finding 82% attributable to algorithmic feed exposure.
• News-consumption polarization (diversity of article slant) is a different outcome from affective polarization (in-group warmth minus out-group warmth on feeling-thermometer scales), as operationalized in the framing.
• Construct validity of affective polarization measures can be compromised when using proxy outcomes; using proxy constructs can lead to type M and type S errors when studying affective polarization as a source or consequence of other variables.

These are challenges this argument’s reasoning pattern must still withstand. Answering them on Isonomia strengthens the argument.

• Is the literature really agreed that defects of kind K bias inferences in direction B, or is the bias direction itself contested?Open
• Does study S actually have defect D, or is the description of S inaccurate?Open
• Is the expected magnitude of the bias from D large enough to overturn S's reported effect, or is the effect robust to plausible bias corrections?Open
• Has S (or a follow-up study) performed a robustness check or sensitivity analysis that addresses defect D directly?Open
• Is this critique applied consistently — i.e., would it apply to studies on the other side of the debate that share the same defect kind K?Open
• Is H supported by independent studies that do not share defect D, such that S's defect does not undermine H itself?Open

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No arguments cite this one yet — no one has built on or contested it. That is an absence of engagement, not a finding of soundness. Build on or contest it on Isonomia to change that.