04 May 2010

On a shorthand argument

In response to

This is in response to a thoughtful post on Less Wrong titled "But somebody would have noticed". The author Alicorn raises a number of fictional scenarios where the argument "but somebody would have noticed" is seen to be mistaken.

A few words about shorthand arguments

"Somebody would have noticed" is shorthand for a certain argument. Like most shorthand arguments, it can be used well or badly. Using a shorthand argument badly is what we mean by a "fallacy".

A shorthand argument is used well, in my opinion, just if you could expand it to the longhand form and it would still work. That's not a requirement to always do the full expansion. You don't have to expand it each time, nor have 100% confidence of success, nor expand the whole thing if it's long or boring. But expanding it has to be a real option.

A list of salient critical questions

Critical questions that arise in expanding this particular argument:

  • What constitutes noticing?
    • Would other people who noticed understand what they saw?
    • Further, would they understand it the same way that we do?
      • How much potential is there for their understanding of the same phenomenon to be quite different from ours?
    • Further, if their understanding is similar to ours, would they express it in terms that we would recognize?
      • This could include actions that we recognize as relating to the phenomenon.
  • Would we know that they noticed?
    • Motivations: Would people who noticed have strong motivations for letting others know or for not letting others know?
      • Would they want others to see that they noticed?
      • Would they want others to see the phenomenon they noticed?
      • Would they want to do something about it that someone could easily see?
    • Ability:
      • If they did want others to know, could they easily show it?
      • Conversely, if they didn't, could they easily hide it?
    • Who witnesses it:
      • Would they want us in particular to see it (or not see it), as opposed to a select group? For instance, they might write a report about it that you and I probably wouldn't see.
      • If they revealed it to others but not directly to us, what's the likelihood that the information would make its way to us?
  • The suppressed premise in that emthymeme is that "Nobody noticed". Since we didn't ask everyone in the world, how did we determine that?
    • What is the population that would have noticed?
    • What sample size did we take?
    • How representative was our sampling?
    • Assuming we have reasonable answers to the above, what level of confidence can we place on our sampling?