Arms and the Businessmen
Q. Is it proper to work in the arms industry?
A. "The arms industry" is too general a term. In order to establish consistent ethical criteria, we will have to make some important distinctions.
The Talmud teaches: "It is forbidden to sell to strangers weapons, or to sharpen their weapons, or to sell them anvils [used for making weapons]." The reason is that we have a reasonable expectation that they will be used to harm others. Later in the same passage, it is pointed out that many do customarily sell arms to others; the Talmud explains that these sales are "to the Persians, who protect us." (1)
The context of this passage indicates that there is a sharp distinction between two kinds of arms sales: one involves selling weapons to private individuals who are suspected of being brigands, bandits, terrorists, and so on. We are warned not to participate in this kind of arms trade in any way: not to sell arms to the users, nor to middlemen, nor to sharpen the weapons and so on.
The other kind of arms trade is to aid a legitimate government that uses weaponry to protect its citizens. This includes protection against lawlessness (police and gendarmerie to protect against bandits and insurrection) as well as national security -- protection against hostile foreign powers. This kind of weapons trade is completely legitimate.
Judaism definitely abhors war and the glorification of war. In ancient times, and even as recently as a few generations ago, wearing a sword was considered a symbol of a gentleman; but the Mishna states that since war is ultimately a disgrace, a weapon can never be considered a furnishing or article of clothing.(2)
Yet Judaism is not a pacifistic religion either. Our tradition has always recognized the realistic need for just laws to be given the backing of the coercive power of the king or state. Jewish communities have generally taken a positive view of their responsibility to participate in the protection of host nations in time of war. (3) Likewise, virtually all authorities have acknowledged the importance of participating in the protection of our own state.
From this we can discern the answer to your question. It is perfectly proper to be involved in arming a legitimate state in order to help it protect its citizens from lawlessness and foreign enemies. When these countries engage in arms sales with allied countries that follow similar legitimate practices, the same permission applies. It seems that the majority of the activities of the large defense contractors fall into this category.
Conversely, indiscriminate arms sales to private citizens have a high likelihood of being used for lawlessness. And certainly arms sales to drug barons or brigands, whether foreign or domestic, are unethical.
An intermediate case exists where governments allow selected private individuals to own firearms for self-protection. In some places, such sales are allowed only in unusual instances when an individual can demonstrate both need for a firearm (example: a person owns a warehouse in a dangerous neighborhood) as well as meaningful evidence that the weapon will be used in self-defense only (example: proof of a clean criminal record). Such sales seem to be within the boundaries of legitimate protection. But in places where standards are minimal, there is a definite ethical problem in selling a dangerous weapon unless the seller has definite reason to believe that the weapon will be used only for legitimate defense purposes.
Even though in today's imperfect world weapons are a necessary evil, we all look forward to the day when "they shall beat their swords into plows and their spears into pruning hooks; nation shall not lift up sword against nation, and they shall not learn war any more" (Isaiah 2:4).
SOURCES: (1) Babylonian Talmud Avodah Zara 15b, 16a. (2) Mishna Shabbat 6:4. (3) See for example Rav Moshe Feinstein, Igrot Moshe, Yoreh Deah II 158.