Without accepting this specific rule, that's not how any rules of evidence work in any (common law) court. There needs to be a point where things are presumed t

Without accepting this specific rule, that's not how any rules of evidence work in any (common law) court. There needs to be a point where things are presumed true to maintain a working court system. Imagine if e.g. you had to prove the _concept_ of DNA testing every time it was used. In the US, see for example the debate between the Frye standard vs. the Daubert standard.