"One objection is that a mandate paternalistically coerces [authors] for their own good. If true, this would be a serious problem for me, though perhaps not for everyone who defends mandates. I cannot support paternalism over competent adults....Fortunately, the paternalism objection misses the target and is easily answered....First, I only support mandates that are conditions on voluntary contracts. They might be funding contracts: if you take our money, you'll have to provide OA to your research; if this bothers you, then don't take our money. They might be employment contracts: if you work here, you'll have to provide OA to your research; if this bothers you, then don't work here....Second, I only support mandates with reasonable exceptions....Third, an OA mandate [advances other interests beyond the author's]. The [author] interest is greater visibility and impact. The university [or funder] interest is that an OA mandate will better fulfill the university [or funder] mission to share the knowledge it produces, and better assist researchers elsewhere who could benefit from this knowledge...."Peter is a philosopher, and thus can be expected to be more careful with choosing his words than a mere mortal like me. Yet I cannot square the idea of a mandate, given its usual definition of 'an official or authoritative command; an order', with the idea of a condition, a stipulation, in a voluntary contract. If you mean starter pistol, don't say machine gun. You might confuse some people. If you mean contract stipulation, don't say mandate. Such a heavy word is, well, too 'loaded' (no pun intended).
And how voluntary is a funding contract actually? Only in the sense that if you don't sign, you have the option of leaving science altogether. In comparison, the condition in a voluntary contract that asks authors to transfer their copyright to a publisher seems a very mild and decidedly benign one, especially if the publisher is 'green'.