Let’s talk about Linda.
In the beginning we are presented with 6 items of information about her which, we are invited to believe, are severally & collectively, true (P=1).
We are then invited to consider which of two further statements is more likely to be true: that she is a bank clerk or that she is both a bank clerk & a feminist.
The first statement comes as a surprise to those of us with our cultural background, or would have done before the current economic emergency: it is very unlikely (P close to zero) that someone with a philosophy degree would be working as a bank clerk. So what do we do?
Well, perhaps, carelessly forgetting that this second statement also contains the idea that Linda is a bank clerk, we just opt for the more likely second half.
Or perhaps we hurriedly revise our decision to reject the first statement (the information comes after all from someone who is an expert on Linda), but still opt for the second statement to reflect that process which we have undergone, of learning & revision in the light of new information .
But when we understand the fallacy, we might look back to the beginning. And reflect on the odd conclusion that the original introductory statement about Linda is even less likely to be true than the one which makes her both a bank clerk & an active feminist.
Probability all depends on where you stand.
We may also be reflecting what is odd, disturbing, but true: that the probability that I am me is even less than the probability that I exist at all. When the sperm met the egg, the I that I undoubtedly am carried only the tiniest probability of me.
I am what I am because of a lifetime of contingencies.
