As About Time 5 points out, a key feature of Season 18 is all the Renaissance trappings. But they miss what this adds to the show. The thing about the Renaissance, from a juvenile SF writer's point of view, is: it was the last time that scientific thought was dangerous. It's not just about the mathematic-mystical side, the symmetric properties of the perfect solids, and the aesthetics. It's about the real-world consequences of trying to find out.

Once you look for it, this is threaded throughout Season 18. The Alzarians in Full Circle have a society devoted to propagating ignorance. The Vampires in State of Decay enforce it; the Trakenites knowingly welcome it; and in Logopolis we finally see raw knowledge becoming raw power. (Warriors' Gate is also about enslaved knowledge challenging entrenched ignorance, but it's not about finding out, it's about knowing, so it's slightly different).

It seems like every incoming script editor thinks Doctor Who has gone "too fantasy" and wants to "bring it back to science" -- Andrew Cartmel said the same. There's a good case to be made that this is an inherently meaningless statement; as implemented it often simply means that a different kind of technobabble is used to explain the denouement. But in Bidmead's hands, in Full Circle, in The Keeper of Traken, in Logopolis, it actually means something. It doesn't mean "have you tried a Fourier Transform?". It's something important and Oedipal.

(Updated to add) This is "Oedipal" in the Sophoclean sense, of course, the sense of someone being destroyed by their own desire for knowledge. I didn't mean that Adric wants to kill the Doctor and shag Romana.