Appeal to ancient wisdom

Lord Dorwin thought the way to be a good archaeologist was to read all the books on the subject — written by men who were dead for centuries. He thought that the way to solve archaeological puzzles was to weigh the opposing authorities. And Pirenne listened and made no objections. Don't you see that there's something wrong with that?

The Appeal to ancient wisdom (AtAW) is a naturalistic fallacy and thus an informal fallacy. It is the unholy love-child of the appeal to tradition and of the appeal to authority. In this sense, the appeal to ancient wisdom can be understood as being the appeal to traditional authority.

The appeal to ancient wisdom is most commonly used by woomongers of the New Age, some indigenous science advocates, and/or alternative medicine varieties. However, some creationist arguments can also count as AtAW, with the Bible as the source of ancient wisdom on the subject of whatever. (Assuming said Bible in its current form ranks as sufficiently "ancient" and pre-civilizationally popular-ethnic...)

Logical form
In its most basic form, it can be written like this;

In physics
From the days of Plutarch and Ptolemy, it was a generally held belief that the presence of garlic would destroy a magnet.

This was apparently held as fact for hundreds of years, until the 1600s, when had the bright idea of actually trying it out. Finding that garlic does not, in fact, have any anti-magnetic effect, he published the results in his Pseudodoxia Epidemica, a sort of 17th-century MythBusters.

A few years later, responded in his Arcana Microcosmi:

In fact, the ancients did indeed make predictions about physical motion based solely on abstract reasoning that could be very simply proven wrong by experimentation. For instance, Aristotle claimed that a ball dropped from the mast of a ship would fall straight down, while the ship moved, and land behind the ship; Galileo, on the other hand, noted that this was not the case, with such a ball in reality landing at the bottom of the mast.

In anatomy
(129 — c. 200/c. 216 CE) was for centuries the go-to guy for medicine and human anatomy in Europe, and his theories came to dominate and influence Western medical science for more than 1,300 years. The problem is that — despite his impressive achievements — he failed to extend his empirical methods (today a core tenet of modern evidence-based medicine) to human beings:

As Wikipedia puts it:

The next step in the chain of error produced by the appeal to ancient wisdom is the fact that Galen had, in turn, been influenced by the incorrect theory of humorism, as advanced by the — to Galen — then-ancient wisdom of (who had lived some six hundred years prior to Galen, c. 460—c. 370 BCE).

To this day, there are many that believe that women have an extra rib.

In herbal medicine
The appeal to ancient wisdom has been documented as long ago as 1597 CE when wrote the book The Herball, or Generall Historie of Plantes, and cited the ancient authorities of Pedanius Dioscorides, Galen, and Pliny the Elder.

In the case of birthwort (Aristolochia spp.), reliance on ancient wisdom has gone horribly wrong. Many people have been poisoned by birthwort over the centuries. The documented medical recommendations for birthwort date back to 300 BCE with, who was a student of Aristotle.

Birthwort was believed not to be poisonous as late as the first half of the 20th century. Birthwort is in fact extremely toxic, but it takes a while for it to kill, so its ill effects were not fully realized until the late 20th century, after the development of modern epidemiology.

That which is ancient need not be wise
How old something is bears absolutely no correlation to how right it is.

Trepanation is a great example. It is one of the oldest medical practices known to mankind, and it is also a heap of absolute bullshit that doesn't work for its traditional uses (but does have some very narrow modern uses in medicine).

You can say the same about the Flat Earth myth, geocentrism, human sacrifice, bloodletting, medicinal lead, mercury, or asbestos, slavery, racism, misogyny, and anything else that people used to believe in.

Indeed, some peoples in Oceania would practice cannibalism of dead and/or captured enemies, thinking that if they did so, it would somehow grant them their slain enemy's captured "life force." In fact, some indigenous Papuan peoples have actually developed a resistance to, a prionic disease gotten from eating human brains. Were these people wise in believing that eating human brains would grant them mystical powers?

Science trumps wisdom
The scientific method shows extremely high predictive success and excellent correlation with reality. Ancient wisdom usually does not. There are many cases where the scientific method simply proves ancient wisdom wrong. For example, the various forms of young earth creationism, most of which are inspired by the ancient wisdom of various "holy" books, are totally and insanely wrong.

There are some cases where science has actually confirmed some form of ancient wisdom — does this vindicate the wisdom in question? Well, no. There are some cases where trial and error testing may have revealed a genuine correlation. However, prescientific cultures will probably have explained the correlation with some form of magical thinking, such as the balance of elements or the presence of spirits.

Herbal medicine
Most herbal medicine books rely implicitly or explicitly on the works of older herbalists and older herbal medicine books. For example, it's true that many cultures have discovered that the bark of certain trees (e.g. such as the willow tree, Salix sp.) could be chewed for pain relief, but they explained this with various non-atheistic explanations. Modern medicine, on the other hand, has isolated the active ingredient in these trees and turned it into aspirin. This is due to the march of scientific advancement, ancient cultures used scientific techniques (rote experimentation and observation) to derive the medical utility of certain plant species, but they didn't have the knowledge or technology to isolate aspirin from the bark of willow trees.

Appeal to modern pseudohistory
In some cases, usually where the woomonger is either lying or deluded, the "ancient" wisdom isn't even ancient, but based on historical inaccuracy.

The Maya Calendar explanation of the 2012 apocalypse is an example — the Maya calendar doesn't actually end on 21/12/12 for various reasons (for example, the Maya had contingencies for restarting their calendar just like we do, and they only had a 365-day year instead of a 365.24-day year).

Some chiropractors and homeopaths also make erroneous appeals to ancient wisdom, claiming that their "medicine" is thousands of years old, when we can track both of them back to the 19th century CE.

Game of telephone
One other core issue with the appeal to ancient wisdom is that, as there's always some prior culture or person to kick back your beliefs to, use of the fallacy quickly turns into a sort of epistemological game of (a.k.a., "telephone game"), whereby increasingly poorly thought-out beliefs are continually propped up through reference to what some old guy or culture allegedly said or did, preferably from way back before people knew what thunder was.