The Mishna (3:9) in today’s daf (Ketubot 41a) informs us that while those responsible for causing personal harm or for damaging the property of another must pay for the damages (נזק) that they have caused, if they confess to causing such harm or damage then they do not pay any additional fines (קנס) that would ordinarily be demanded of them in such a situation.
Having drawn this distinction between ‘damages’ (נזק) and ‘fines’ (קנס), our Gemara then references Gemara Bava Kamma which states how the owner of a previously violent ox (שור המועד) which subsequently causes further harm must pay full damages (נזק שלם), while someone whose ox that has not previously been violent (שור תם) need only pay half-damages (חצי נזק).
Clearly, in the first case (of the previously violent ox), what is being asked to be paid is not a fine but, instead, full damages (נזק). The question, however, is how do we categorize the payment of half-damages (חצי נזק) in a case involving a non-previously violent ox? Is this, as Rav Papa suggests, merely a diluted version of ‘damages’ (נזק) which technically should be paid in full, but which is reduced in this case to half given that this is a ‘first offence’? Or is this, as Rav Huna suggests, a ‘fine’ (קנס) required of the owner who technically should not be required to pay anything but who is being taught a lesson to be more responsible by being required to pay the fine?
On first glance we may ask why it makes a difference?! However, the difference is based on the principle that we learnt in our Mishna whereby if half-damages (חצי נזק) falls under the rubric of ‘damages’ (נזק) then it is paid in all cases, whereas if half-damages (חצי נזק) falls under the rubric of ‘fines’ (קנס) then someone who confesses that their ox caused damage would not be required to pay.
Significantly, the Gemara’s conclusion is that we follow Rav Huna and that half-damages (חצי נזק) is considered to be a קנס (fine). But why is someone who confesses to causing harm or damage exempt from paying a fine?
As previously noted, the reason why a fine is generally demanded is to teach someone a lesson that they should take greater care and they should act more responsibly (see Bava Kamma 15a). Given this, as Rabbi Nachum Eliezer Rabinovitch explains (in his commentary to Hilchot Nizkei Mamon 2:7), if someone admits to what they have done, this itself proves that they understand and are aware of their responsibilities.