Edward, seeing this invitation as a chance to assert his claim as overlord of Scotland, chose John Balliol, whom he judged to be the weaker of the two.
Edward thought that John Balliol was the stronger option.
mnli hypothesis: Edward thought that John Balliol was the stronger option. premise: Edward, seeing this invitation as a chance to assert his claim as overlord of Scotland, chose John Balliol, whom he judged to be the weaker of the two.