The following quotation is sometimes attributed to Thomas Jefferson:
Laws that forbid the carrying of arms ... disarm only those who are neither inclined nor determined to commit crimes. Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than prevent homicides, for an unarmed man may be attacked with greater confidence than an armed one.
This statement is not something Jefferson wrote, but rather comes from a passage he included in his "Legal Commonplace Book." The passage is from Cesare Beccaria's Essay on Crimes and Punishments, originally published in Italian in 1764.1 It appears in Jefferson's commonplace book as follows:
Falsa idea di utilità è quella, che sacrifica mille vantaggi reali, per un inconveniente o immaginario, o di poca conseguenza, che toglierebbe agli uomini il fuoco perchè incendia, e l'acqua perchè annega; che non ripara ai mali, che col distruggere. Le leggi, che proibiscono di portar le armi, sono leggi di tal natura; esse non disarmano che i non inclinati, nè determinati ai delitti, mentre coloro che hanno il coraggio di poter violare le leggi più sacre della umanitàè le più importanti del codice, come rispetteranno le minori, e le puramente arbitrarie? Queste peggiorano la condizione degli assaliti migliorando quella degli assalitori, non iscemano gli omicidi, ma gli accrescono, perchèè maggiore la confidenza nell'assalire i disarmati, che gli armati. Queste si chiaman leggi, non preventrici, ma paurose dei delitti, che nascono dalla tumultuosa impressione di alcuni fatti particolari, non dalla ragionata meditazione degl'inconvenienti, ed avvantaggi di un decreto universale.2
Jefferson's only notation on this passage was, "False idee di utilità."3
The English translation of this passage, which appeared in the 1809 edition that Jefferson later owned, is as follows:
A principal source of errors and injustice are false ideas of utility. For example: that legislator has false ideas of utility who considers particular more than general conveniencies, who had rather command the sentiments of mankind than excite them, who dares say to reason, "Be thou a slave;" who would sacrifice a thousand real advantages to the fear of an imaginary or trifling inconvenience; who would deprive men of the use of fire for fear of their being burnt, and of water for fear of their being drowned; and who knows of no means of preventing evil but by destroying it.
The laws of this nature are those which forbid to wear arms, disarming those only who are not disposed to commit the crime which the laws mean to prevent. Can it be supposed, that those who have the courage to violate the most sacred laws of humanity, and the most important of the code, will respect the less considerable and arbitrary injunctions, the violation of which is so easy, and of so little comparative importance? Does not the execution of this law deprive the subject of that personal liberty, so dear to mankind and to the wise legislator? and does it not subject the innocent to all the disagreeable circumstances that should only fall on the guilty? It certainly makes the situation of the assaulted worse, and of the assailants better, and rather encourages than prevents murder, as it requires less courage to attack unarmed than armed persons.4
The English translation of this passage originally quoted above, and the one most often seen on other Internet sites, is most likely a later translation. It may be taken from a 1963 translation by Henry Palolucci.5