The police are taxpayer funded enforcement of the things in your house and in your bank. Should personal property and wealth savings also revert to the public because of this? It would be a stronger argument if the creation of the work was taxpayer funded, then that would be a decent reason to have the protections lapse eventually.

IP is not property. If you put your chair on display, then yes, people should¹ have a right to make a similar chair and copy and share ad infinitum, but taking the original chair itself would be a no-no. It's not a good comparison.

To take thing further, there are various takes on personal property, with broad acceptance that yes, personal property should (gradually) revert to the public (taxes), otherwise very bad things happen (see inequality). Some societies do not have personal property beyond some personal items. Property/ownership has vast negative consequences (exacerbating greed, poverty, starvation, mass suffering; many wars are fought for property), though I'd agree it is in many ways better than alternatives, especially if the state and taxation dulls some of the sharp edges.

¹ By default. We may argue to what extent some restrictions may be reasonable as an imperfect way to achieve a certain goal.

> IP is not property.

It is, and not just because it is in the name. It is the right to exclude people from a defined set of actions with regard to a defined subject, which is exactly what property is.

(Now, you may think it is not, in your value system, the kind of thing in which property rights naturally exist, and it's pretty clear that the authors of the copyright clause were at least sympathetic to this for the kinds of IP it authorized, which are limited in scope and to advance a defined public purpose.)

> It is the right to exclude people from a defined set of actions with regard to a defined subject, which is exactly what property is.

That is not what property is.

Ownership of property is the right to decide how a good will be consumed (i.e., used up). It means that the property owner can consume the good without needing anyone else's permission, and conversely that anyone else requires the owner's permission to take any action with regard to the good which would result in its consumption—whether temporarily or permanently. However, this limited exclusivity is a consequence of scarcity, and not central to the definition of property. If someone else can can derive some benefit from the property—for example, by painting a picture of someone else's house—without interfering with the owner's use, they are perfectly free to do so, as this does not involve consuming the good, and the owners' rights remain intact.

Only scarce, rivalrous goods are subject to being used up. Superabundant goods, which includes everything to which copyright and patent rules might apply, cannot be consumed, even temporarily. One person's use of or benefit from the copyrighted work or patented process does not interfere with anyone else using or benefiting from the same work or process. As such, there is nothing here to which the concept of ownership may be applied.

> That is not what property is.

No, the ability to exclude others is exactly what property is.

> Ownership of property is the right to decide how a good will be consumed

Exclusivity is the defining feature of property interests. It's true that there is a common view of rights to consumption and alienation as dividing those property interests that constitute “ownership of property” (that is, ownership of the subject of a property interest) from those that are mere “ownership of an interest in property”, but that's not germane to whether or not IP is property though it might be to whether the subjects of IP are genuinely “owned” by the private holders of IP rights.

Obviously we are approaching this in the context of different frameworks with different definitions of property. IMHO attempting to define property as a right to prohibit others from deriving any benefit from the good—regardless of whether their actions affect your own use of the good—is self-contradictory, contrary to human nature, and a source of needless conflict. Scarcity is the obstacle here, and property is how that obstacle is addressed. If there is no scarcity then there is simply no point in attempting to allocate property rights—you're taking something superabundant and making it scarce for no net benefit.

Even if you do stretch the definition of property to include copyrights and patents, however, the fact remains that these are non-rivalrous goods, which implies that you are not harmed when someone else ignores your claim to exclusivity. No response involving force (including fines, imprisonment, etc.) could ever be proportional to the supposed offense, which means this is a "right" you cannot justly enforce.

Exclusivity, and the ability to justly enforce it, are common characteristics of property exactly because most of the things people try to classify as property are scarce and rivalrous. You can try to extend the definition to include things which are neither scarce nor rivalrous, but if you do so then the justification for enforcing property rights no longer applies to all such "property". At that point you've accomplished little beyond turning the word "property" into a useless label that could be applied to almost anything and which does not imply anything about the rights of the property owner.

I didn’t argue that IP was property. I responded to the suggestion that the reason to have a limited copyright term is because enforcement is taxpayer funded. I’m pointing out that this reasoning is inconsistent and has no strong basis.

I'm pointing out your reasoning is unfounded non sequitur. Physical property does indeed revert to public domain, hence it does not make sense to add requisites for release of intellectual restrictions. Requiring public funding for only-temporarily-private IP would make things more inconsistent.