Text and context

[MarcoP]

I cannot stress this enough: having both C14 analysis and fashion available to us and overlap so nicely is a tremendous luxury. This is not conclusive, it is double conclusive. Why struggle?

Hi Koen, I agree with what you write but I am not sure about the last sentence.
Probably I am having trouble with my bad English, but I understand "conclusive" as 100% certain. If this is so, the joint evidence from C14 and fashion is not conclusive, but it is stronger than either of the two alone. It is not totally inconceivable that the parchment was used 12 years later than the C14 range. It is not totally inconceivable that the manuscript reproduces 20 years old fashion. Both facts are unlikely, and the probability of them both happening together is even more unlikely. Both pieces of evidence are solid: taken together they are very solid, maybe 99% solid, but still not 100% sure (conclusive).
Any theory that contradicts this evidence should present equally (99%) solid evidence for a different date. Extraordinary claims require extraordinary evidence. Let's see this evidence, at least: the same costumes from several 1450s manuscripts; proof of XV Century manuscripts being frequently written on decades old parchement; a different opinion from someone as qualified as Wieck... In the absence of such extraordinary evidence, theories that conform to the C14 date range are clearly preferable.

This of course only holds in the context of science and palaeography: allergy to these criteria implies that everything is equally valid and pet theories can be freely chosen by personal preference (no straitjacket, bingo!). We are left with what I like vs what you like; since "in matters of taste, there can be no disputes" all discussion becomes totally pointless.