Great BA fallacies #3 - Begging the question

This fallacy creeps in just when you don't expect it - and I should know: I've been right about every other fallacy so I'm right about this one!

And there is the fallacy: I assume that because I've been right every time before (please remember that this is a made up example before reminding me of all my mistakes!) that I will be right in the future.

It's like saying that because I have flipped a coin 3 times and it has come up heads each time that the next time must be tails. No - each time I flip it there is a 50:50 chance of it being heads regardless of what happened on the last 3 or 5 or 100 flips.

Past performance is no indicator of future performance. Such reasoning that assumes an outcome in order to justify the outcome is begging the question.

Here's a classic BA example of it: "we tried that before and it didn't work". The inference is that because we tried it before and it didn't work if we try it again it won't work. The truth of the outcome will be determined by why it didn't work before and whether those factors still apply.

This fallacy ties in nicely with fallacy #1 - argument from authority - just because some 'authority' says something does not make it true: don't just believe someone because they have a reputation for being right or knowing a lot about something, that would beg the question of whether they are right in this case as well. You may want to use the person's track record as evidence that their opinion is worth considering - but it is NOT evidence that they are right.

Sometimes I get asked about how to Project Manage a project I am doing the analysis on: "you're doing a good job on the analysis so how should we restructure the project plan". I don't know! Project Management is a separate skill set I don't possess - asking me on the basis I am doing well with the analysis maybe flattering but would still result in (very probbaly) the wrong answer, so it is in both our interests for me to declare that.

Begging the question - assuming that we know the answer before asking the question and basing our answer on that false assumption - it gets everywhere and it always has caused trouble so it always will!

Whoops...