= Solution
\b[The <club principle> predicts a cofinal countable ladder contained in every uncountable subset of $\omega_1$.] More precisely, $\clubsuit$ asserts that there is a sequence $\langle A_\delta:\delta\in\lim(\omega_1)\rangle$ such that each $A_\delta$ is cofinal in $\delta$ with <order type> $\omega$, and every uncountable $X\subseteq\omega_1$ contains at least one entire $A_\delta$. It predicts a countable ladder contained in $X$, rather than predicting $X\cap\delta$ exactly. The latter is the stronger kind of guessing in the <diamond principle>.
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