The Ship of Theseus

This seems appropriate to post in honour of the actor, Roger Lloyd-Pack, who passed away today. Not only gave us the unforgettable Trigger, but also Owen in The Vicar of Dibley. And for Potter fans, Barty Crouch Sr. He was one of those great character actors who inhabited the roles he played that generally go unsung compared to often, less talented stars.

To anyone who doesn't remember it, there's a moment in Only Fools and Horses where Trigger gets an award for keeping his broom for 20 years. Then remarks that it's had 17 new heads and 14 new handles. It's funny because of course, what seems like a great achievement isn't really.

But there's a philosophical question in this too, that was originally asked long ago by Plutarch when referring to replacing all the timbers on the Ship of Theseus: if you replace all the timbers on a ship over time (or the head and handle on a broom), is it still the same ship?

"We would rather die once than fear death every day"

A senior sherpa, called Mr Sherpa, on top form. From the BBC:

The Mount Everest region's Sherpas have said they are angry at the way studies of glaciers and glacial lakes have been conducted in recent years. They say the studies do not involve them and that results are often spread through alarmist media reports that cause panic among locals in the area.

"Everytime we begin to forget about the threats from glacial lake outburst, then comes news of yet another study through the radio and television, and this has been happening over and over again for more than 15 years now," said Mr Sherpa.

"Instead of having to fear death like that again and again, we would rather die once if the lake really bursts out one day."

Rumours of glacial lake outburst are also said to be causing panic among the locals. Two months ago, following a television report on the risk of a glacial lake outburst in the region, many families in the lower belt of the Everest region fled their homes overnight.

Mr Sherpa said he and other villagers recently received late-night phone calls from people in a village downstream who were inquiring if the Imja glacial lake had burst.

"We were so scared because they were seeking confirmation from us after they heard rumours that sirens had gone off nearby the Imja lake, and we did not even know if the sirens had already been installed."

Ceteris paribus

From Wiki:

A ceteris paribus assumption is often fundamental to the predictive purpose of scientific inquiry. In order to formulate scientific laws, it is usually necessary to rule out factors which interfere with examining a specific causal relationship.

Under scientific experiments, the ceteris paribus assumption is realized when a scientist controls for all of the independent variables other than the one under study, so that the effect of a single independent variable on the dependent variable can be isolated. By holding all the other relevant factors constant, a scientist is able to focus on the unique effects of a given factor in a complex causal situation.

So, for example, if we want to find out whether treacle is more viscous than water, we take two identical containers, and fill one with treacle and the other one to the same depth with water; at the same temperature and height above sea level etc; we place an identical object on the surface of each liquid; release them at the same time; and then we compare how long it takes each object to reach the bottom of the container.

If you fill one container 50cm deep and the other one 100 cm deep; if you drop a ball-bearing into one liquid and a flip-flop into the other; or if you carry out the water experiment in the International Space Station high up in orbit and the treacle experiment at sea level, then the result will be meaningless.

Which brings us to the time worn KLN at comment 18 here:

Why should Mr X in a 2/3 bed house with reasonable size garden, growing his own veg to survive, pay more than his neighbour, a family of 4 all working adults, in a 3/4 bed on a slightly smaller plot of land?

The 'dependent variable' in this case is each household's LVT bill. The questioner keeps two variables constant - the fact that both plots are in the same geographical area and both are being used for residential/hobby purposes - and makes the reasonable assumption that the real 'independent variable' is the plot size (see footnote), so why does he change at least four other variables as well?
* Household size
* Number of working adults
* Number of bedrooms
* The use to which the garden is being put

These are irrelevant and the only way to do a fair comparison, and thus obtain a meaningful answer, is to keep these constant. I gave the following examples:

* "Why should Mr X in a 2/3 bed house with reasonable size garden, growing his own veg to survive, pay more than his neighbour, Mr Y in a 2/3 bed on a slightly smaller plot of land next door, growing slightly less of his own veg to survive?"
Answer: because Mr X occupies more land.

* "Why should a family of 4 working adults in a 3/4 bed house with reasonable size garden, pay more than their neighbours, another family of 4 working adults, in a 3/4 bed on a slightly smaller plot of land?"
Answer: because the first household occupies more land.

* "Is it fair that Mr X in a 2/3 bed house with reasonable size garden, growing his own veg to survive, pays exactly the same as his neighbours, a family of 4 all working adults, in an identical 2/3 bed on the same sized plot of land?"
Answer: yes, because both households are occupying the same amount of land.

You can then make up your own comparisons, remembering always that only one factor may be varied, and then you decide on which plot the LVT would be higher and ask yourself whether this seems reasonable: perhaps Mr X's neighbour is a farmer with a 2/3 bed house with a hundred acres of land, who grows so much veg that he has a huge surplus that he can sell at a profit to buy other things, for example. Who would pay more LVT and would this be reasonable?

Footnote: Actually, it is planning permission which is the independent variable - if Mr X would love to extend his house to 3/4 bedrooms, sacrificing part of his large garden in the process, but planning laws prevent him doing so, then it is quite possible that the LVT bill on the smaller plot with more generous planning permission would be higher, but let's gloss over that.