Howdy!
I came across a term (which I lost) for the notion that the longer an object has existed, the longer it is likely to exist,
As in, if a book has been on the market for 6 months, it’s likely to survive another 6 months.
If a book has been on the market for 12 months, it’s likely to survive another 12 months.
I assume it is related to a power law and/or infant mortality of objects.
Any idea what the term is?
My home inspector used it when inspecting my 135yr old house before purchase.
He said, if it was maintained, it would easily stand another hundred years.
Adding that new builds he’d seen would not likely last as long.
No answer, but it’s also true when it comes to actuarial tables and human life span.
OP: I think it might relate to the Principle of indifference, especially when it comes to the restated question “When, in terms of its overall lifespan, have I happened to encounter this thing?” Without strong evidence one way or the other, the guess that you came across it halfway through its lifespan is perfectly indifferent. Thus, it will last approximately as long as it has already existed.
Surely not, since we have better data for average human life span. Most 6-month old babies will tend to “last longer” than most 80-year-old people, on average. We’re not talking about current age being correlated with overall lifespan (which would be self-evident,) but with potential additional lifespan, as I understand it.
I’ve read the concept in Nassim Nicholas Taleb’s book Antifragile. I just can’t remember if there was an explicit term.
The life expectancy tables are…non-intuitive.
Your remaining life expectancy does not drop 1:1 with time passed, so you get things like an 80 year old with a life expectancy of 10.2 more years, but if they turn 90, they’ll have a life expectancy of 5.5 more years.
Of course most 80 year olds aren’t going to make it another 10 years - it’s the outliers who bump up the averages.
Many people buy antique furniture on the notion that if it lastest 100 years of use it’s probably better built than most new furniture and will last another 100 years. I think this may be true for most things except for fancy beds. Fancy beds are usually bought by people when they get older and they don’t get put to the torture test that younger buyers may put them thru.
That effect would exist even without big outliers. The population of 80 year olds with overall life expectancy of 10 years contains people who will live to 85 and people who will live to 95. When you check on them again at age 90, you stop folding the ones who died at 85 into the average, so naturally the “average age at death” goes up.
That effect holds even if the original distribution was totally symmetric.
I think I’ve seen this idea associated with the Principle of mediocrity as well. If the Great Pyramid is 4500 years when I visit it, it would be surprising if it was destroyed less than 450 from now, because that would mean that I happened to visit it in its last 10% of existence; similarly it would be surprising if it lasted 40000 more years, since that would mean that I visited it in its first 10% of existence. It’s not a very tight bound, but if you’ve got no other information, it’s better than nothing. See also “Carter Catastrophe”
Well, yes. That’s the same thing as saying that it’s an expectancy/estimate/approximation, not a perfect prediction of the date thou shalt perish. 
I have found this to be true for refrigerators.
The physicist J. Richard Gott, in his very readable book Time Travel in Einstein’s Universe, discusses it under the heading of the Copernican principle.
Yeah, Gott must be who I was remembering. Here’s an excerpt about the topic If the Universe Is Teeming with Aliens ... WHERE IS EVERYBODY?: Fifty ... - Stephen Webb - Google Books
Mechanical objects fail according to a bathtub curve. Lots of initial failures in the beginning (quality control issues), constant low failure rate for a long period, and finally high failure rate as things wear out with age. So you can see that for newly manufactured products, there is a high chance of failure, but for devices that have existed a while, there’s a much higher chance it will last a long time.
Things that don’t have mechanical parts only fit the first half of this curve. Electrical devices (except for their mechanical components, such as knobs, turntables, etc.) fail a lot at first, and then settle into a low failure rate forever. (I learned this in college when comparing the lives of mechanical devices to electrical devices – I don’t know how it generalizes, but I can guess). I would assume other devices that aren’t stressed much mechanically behave similarly – display cases, walls, windows that don’t open, etc.
There’s also the survivor bias. Time is like a sieve, filtering out the crap from the past and leaving only the rugged, well made stuff. The only houses left from the 1700s are the good ones. Probably most houses from that time period were built poorly and were demolished or destroyed centuries ago. But the ones that are left sure are durable and well made! So it colors our perception of 18th Century construction methods in general. Most things built in the 1940s are rotting in dumps or disintegrated to oblivion by now. But my mom always manages to find some ancient tin soldier or coffee table at a thrift store and waxes nostalgic about how much better they made things back then!
I was thinking it was about the sieve thing: that, say, most books that manage to continue to be printed for six months are expected to still be on the market after a year, and so on.
I think I remember it explicitly referred to non living objects.
The book thing was one of the examples.
Found it! Lindy Effect