According to Ayn Rand, physical force is the only means of violating man's rights. Extortion, fraud, and unilateral breach of contract are given as examples of "indirect" physical force. [citation: Ayn Rand Lexicon] Although she does not state this, I presume violating patent or copyright rights would be additional examples of initiating "indirect" physical force.
My question is, how can we define physical force? For me, it seems like the difficult part is defining it in such a way that "indirect physical force" is a valid concept.
One hypothesis: "Physical force consists of violating rights." (Then, "direct" physical force applies to material property; "indirect" physical force applies to intellectual property.) Unfortunately, I think this is invalid: what about retaliatory force, or force occuring outside of a context of rights (e.g. between two animals)? Also, this would make Ayn Rand's statement that physical force is the only way to violate rights a truism (or maybe it would just make the statement "true"...)
Second hypothesis (iterating on the previous hypothesis): Perhaps physical force consists of infringing upon someone's possessions (not necessarily rightful possessions, i.e., property as recognized by property rights). For example, taking a rocket launcher away from Saddam Hussein would be use of physical force, since he posssess it, even if he does not possess it rightly. Killing a chicken is using physical force, since it possess its body. Indirect physical force consists of infringing upon someone's "intellectual possessions", which actually is equivalent to "intellectual property" since you can't "possess" something intellectually unless intellectual property rights are recongnized.
I don't see anything wrong with the second hypothesis but would greatly appreciate any feedback!
Physical force doesn't need a social or political definition. It is what physics regards as physical force. That includes magnetic fields and ray-guns and poisonous clouds of gas and sound-rays and fists and bullets. When the actions of one person, via such as these things, injures another's person or property, a violation of rights has occurred.
Indirect physical force involves holding something by physical force though it was taken into possession by (non-physical) fraud, etc. It is the possession and disposition of another's property that constitutes the physical element. It is indirect because the perp didn't wrest it out of the owner's hands, but tricked him out of it.