Karl Popper attended the Mont Pelerin Society's 1947 founding meeting but is on record objecting beforehand to Hayek's exclusionary format

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Karl Popper was among the roughly three dozen invitees at the founding meeting of the Mont Pelerin Society, the classical-liberal society Friedrich Hayek convened in 1947. Per Peter Boettke's review of the Hoover Institution's 2022 published transcripts, Popper did not simply accept the guest list Hayek assembled:

"Hayek also received criticism of his plan from Karl Popper, who was the diametric opposite of Mises. Any meeting that would be useful, Popper insisted, must also have participants who were closer to the socialist position. Hayek stuck to his plan and both Mises and Popper attended, despite their reservations." — Boettke, review of Mont Pèlerin 1947 (Caldwell, ed.), The Independent Review 27:3 (Winter 2022/23)

The Hoover Institution's own announcement of the volume names Popper among "men such as Hayek, Milton Friedman, Aaron Director, Frank Knight, Walter Eucken, Karl Popper, and other leading figures" (Tier 3; the announcement does not name Polanyi). The full attendance roster — including Michael Polanyi among the roughly three dozen who joined Hayek, Mises, and Popper at the meeting — is given in Boettke's review (Tier 2). On the evidence gathered, Popper's Mont Pelerin role reads as a biographical thread separate from Polanyi's — the two attended the same meeting for independently documented reasons — and does not bridge back into the vault's tacit-knowledge/automation or prematurity-of-discovery clusters. This is consistent with, not contrary to, observation-michael-polanyi-person-bridges-three-vault-clusters-invisible-to-vault-bridge, which found that it is Michael Polanyi himself, not Popper, who person-bridges those clusters. Popper's independent recurrence in the vault is via Heuer's Popperian-falsification grounding of Analysis of Competing Hypotheses (claim-heuer-grounds-ach-in-cognitive-psychology-decision-analysis-scientific-method).