Reference for Bava Kamma 70:13

ומדסיפא ניזק שמא ומזיק ברי רישא נמי ניזק שמא ומזיק ברי

— You conclude then that the Mishnah deals with a case where one party was certain and the other doubtful.<span class="x" onmousemove="('comment',' In which case the argument contained in the preceding note could no more be maintained. ');">¹¹</span>

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