hold (或 take) someone hostage

seize and keep someone as a hostage

把某人持为人质

a hostage to fortune

an act, commitment, or remark which is regarded as unwise because it invites trouble or could prove difficult to live up to

招惹麻烦（或不明智、很难做到）的行为（或许诺、话语）担风险

making objectives explicit is to &B{give a hostage to fortune}.

使目的明确就要承担风险。