I have often marveled that the American Revolutionaries went to war—with all the death and destruction that entailed—over their taxes being too high without much say from them in the matter. But their perspective becomes clear when one realizes how well-versed many of the key players were in the writings of John Locke. In section 18 of his 2d Treatise on Government: “On Civil Government,” John Locke writes: 

This makes it lawful for a man to kill a thief, who has not in the least hurt him, nor declared any design upon his life, any farther than by the use of force, so to get him in his power as to take away his money, or what he pleases, from him; because using force, where he has no right, to get me into his power, let his pretence be what it will, I have no reason to suppose, that he, who would take away my liberty, would not, when he had me in his power, take away every thing else. And therefore it is lawful for me to treat him as one who has put himself into a state of war with me, i. e. kill him if I can; for to that hazard does he justly expose himself, whoever introduces a state of war, and is aggressor in it.

The key argument here for equating theft with war is a slippery-slope argument. Why would someone who steals from me a little stop at that if they find they can get away with it? Sometimes there is an answer to this question: for example, the thief (whether or not correct in that view) may feel he or she is righting a finite wrong by stealing something back. Or the thief may only steal barely enough to keep his or her family from starvation. The headiness of getting away with a theft might tempt even such a thief with limited initial intentions to go further. But if a thief really does have principles that strictly limit his or her stealing, such a limited thief is not at war with me in the same sense as a thief who just wants stuff and recognizes no limitations on what he or she will take other than the limitations of prudence in not getting caught. 

Theft may not involve immediate physical injury, but the reality of human existence is that we need things around us to achieve all that we want to achieve. And most of us feel quite bereft when we are thingless. If a thief steals our things, it often feels as if a part of ourselves has been stolen. 

In economic theory and in economic practice, rampant, unchecked theft leads to dramatically lower levels of production and saving, impoverishing entire societies. Limited, principled theft also has a negative effect on production and saving, just not as big.  

In "The Government and the Mob," I wrote

... the basics the government must provide to make anything close to market efficiency possible:

1. blocking theft,
2. blocking deception, 
3. blocking threats of violence.

and quoted from "Leveling Up: Making the Transition from Poor Country to Rich Country": 

The entry levels in the quest to become a rich country are the hardest.  The basic problem is that any government strong enough to stop people from stealing from each other, deceiving each other, and threatening each other with violence, is itself strong enough to steal, deceive, and threaten with violence.  Designing strong but limited government that will prevent theft, deceit, and threats of violence, without perpetrating theft, deceit, and threats of violence at a horrific level is quite a difficult trick that most countries throughout history have not managed to perform.

The situation is not perfect in the United States and other rich countries, but to a remarkable degree we have accomplished this difficult trick. We have much to complain about in relation to our government, but things could be much, much worse. Even those who consider taxation to be theft must admit that, in the US and many other rich countries, taxation is done in accordance with democratic beliefs that keep taxation from going all the way down the slippery slope to enslavement of taxpayers. So democratic governments are at worst limited thieves. 

Anyone who wants to avoid being my enemy needs to declare principles that limit how much he or she would take from me if possible. Anyone who does not set such limits, articulate those limits, and stick to them, should not be surprised when I fight back tenaciously, even if in their own minds they think they have justice on their side. 

Background Reading: Democracy is Not Freedom