Anecdotal Evidence

[Mister Agenda]

What we're talking about here is basically Bayesian Probability. The likelihood of a proposition or claim is calculated based on prior knowledge. Propositions or claims that contradict knowledge we already have are assigned lower probability than propositions or claims consistent with our prior knowledge.

I tied my shoes this morning. I tied my shoes this morning with telekinesis. The former is more probable than the latter because the latter involves a method of tying shoes that has never been proven to exist and has issues re: the laws of biology and physics. Therefore, it is reasonable to require more evidence to accept the latter claim than to accept the former. Also note the difference in consequence: Even if I'm lying about tying my shoes (maybe I'm barefoot or wearing sandals or something), what does your mistaken acceptance of my first claim cost you? Nothing. Accepting my second claim, however, has implications for the breadth and depth of human knowledge thus far...you should be very skeptical and require a high level of evidence before believing it. Way more than my anecdote.

[RoadRunner79]

What we're talking about here is basically Bayesian Probability. The likelihood of a proposition or claim is calculated based on prior knowledge. Propositions or claims that contradict knowledge we already have are assigned lower probability than propositions or claims consistent with our prior knowledge.

I tied my shoes this morning. I tied my shoes this morning with telekinesis. The former is more probable than the latter because the latter involves a method of tying shoes that has never been proven to exist and has issues the laws of biology and physics. Therefore, it is reasonable to require more evidence to accept the latter claim than to accept the former. Also note the difference in consequence: Even if I'm lying about tying my shoes (maybe I'm barefoot or wearing sandals or something), what does your mistaken acceptance of my first claim cost you? Nothing. Accepting my second claim, however, has implications for the breadth and depth of human knowledge thus far...you should be very skeptical and require a high level of evidence before believing it. Way more than my anecdote.

How do you calculate what you do not know?

[GrandizerII]

What we're talking about here is basically Bayesian Probability. The likelihood of a proposition or claim is calculated based on prior knowledge. Propositions or claims that contradict knowledge we already have are assigned lower probability than propositions or claims consistent with our prior knowledge.

I tied my shoes this morning. I tied my shoes this morning with telekinesis. The former is more probable than the latter because the latter involves a method of tying shoes that has never been proven to exist and has issues the laws of biology and physics. Therefore, it is reasonable to require more evidence to accept the latter claim than to accept the former. Also note the difference in consequence: Even if I'm lying about tying my shoes (maybe I'm barefoot or wearing sandals or something), what does your mistaken acceptance of my first claim cost you? Nothing. Accepting my second claim, however, has implications for the breadth and depth of human knowledge thus far...you should be very skeptical and require a high level of evidence before believing it. Way more than my anecdote.

How do you calculate what you do not know?

Prior probabilities don't have to be accurate. You could have 50/50 for all I care. Eventually, after a series of these calculations, you'll have to accept that some events are just more probable than others given what we do know is real in this world.

[The Grand Nudger]

How do you calculate what you do not know?

It hardly matters how if we can't be consistent -regardless- of what we consider to be knowledge.  If, for example, god anecdotes are credible while alien anecdotes are not.

[Pat Mustard]

Tazzycorn

What you, and many people, don't get is that there is no point where anecdote becomes evidence. That is because anecdotes are based on personal memories, which are extremely fallible, due to having huge fallibility isseues, prejudice issues and unconscious bias issues (which apply equally to me as to thee). As a result they are not testable, verifiable or replicable, and therefore do not satisfy criteria needed ot qualify as evidence.

That being said anecdotes have a use in science, as they can point out interesting areas for further research, but for the research to be valid the initial anecdote has to be dropped, just as initial results from anything else that leads to a research study. The reason can be seen with card reading research in the 70s where initial high results weren't discarded for subsequent trials [initial high score predicters were invited back for further prediction tests], and people reverted to the mean in tests a lot more slowly than they should have. If the first results were dicarded for subsequent tests the results would have immediately been seen as random.

So from what others have argued, I'm guessing, that I should believe that the scientist from the first positive tests, where either lying or delusional?  Since the test's could not be repeated, they must be mistaken or in some way they did not occur as reported.

Please elaborate as to what you're talking about. Because what you are saying now is nonsense.

[Pat Mustard]

... and historical matters, testimony is considered evidence, ...

Actually, in history testimony is considered as little better than it is considered in science. It's just that in history, sometimes, testimony is all there is to go on. But if there is anything else, e.g. documentary evidence, or archaeological evidence, that contradicts the testimony, the proper course of action is to throw out the testimony as unsupported assertion.

For example there's lots of testimony that people with only one giant foot lived in Southern Africa from the time of the Age of Navigation explorations, we do not consider that testimony to be anything other than raiméis, simply because there is no evidence that any such creature inhabited the area, and plenty of evidence that the people who did were just as they are now physiologically.

[The Grand Nudger]

Similarly, in a court, no amount of accusations will prove a case.  All the "I saw him do such and such " anecdotes in the world amount to nothing without corroborating evidence that something has, in fact, been done.

[Arkilogue]

How do you calculate what you do not know?

With all the fingers you don't have.

[downbeatplumb]

I went to work today and saw a crashed car is an anecdote it is fairly banal. There is a flying elephant outside my window reciting poetry in the jazz style. Is also an anecdote. One of these is more likely to be true than the other. One may also have left some evidence behind bits of broken glass and such. Not all anecdotes are equal and the less sensational ones are more likely to be true.

[bennyboy]

How do you calculate what you do not know?

Qualitatively.

I don't know if there are any unicorns, and I do not know the number of grains of sand on Earth. However, if A tells me he saw a unicorn, and B tells me he saw a grain of sand, I can pretty easily tell you which one I consider more probable.