The premise that US-specific algorithmic tuning explains US-specific polarization is unsupported speculation; US-specific non-algorithmic factors (two-party system, partisan media, elite polarization) are more parsimonious explanations.

[UNDERMINE → premise #2] Cross-national divergence in polarization trends exists despite similar social media diffusion across developed democracies. The US has distinctive non-algorithmic features (two-party system, partisan cable news ecosystem, high elite polarization) that distinguish it from other democracies with similar platform adoption. Therefore, The premise that US-specific algorithmic tuning explains US-specific polarization is unsupported speculation; US-specific non-algorithmic factors (two-party system, partisan media, elite polarization) are more parsimonious explanations. (Warrant: When multiple US-specific factors could explain cross-national divergence, attributing the divergence to US-specific algorithmic tuning without evidence is less parsimonious than citing known institutional differences.)

• Cross-national divergence in polarization trends exists despite similar social media diffusion across developed democracies.
• The US has distinctive non-algorithmic features (two-party system, partisan cable news ecosystem, high elite polarization) that distinguish it from other democracies with similar platform adoption.

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

• Is there a plausible alternative hypothesis that has not been considered or that would explain the facts at least as well?Open
• Could the facts be jointly explained by a conjunction of weaker causes rather than a single dominant H?Open
• Could the body of facts F itself be an artifact of selection, measurement, or reporting bias rather than a real phenomenon needing causal explanation?Open
• Does H actually explain the full body of facts F, or only a salient subset?Open
• Are the criteria used to judge H 'best' (scope, simplicity, mechanism, prior probability) appropriate for this domain, and are they applied consistently across the alternatives?Open

No one has cited this argument yet.

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.