Prosecutors' fallacy

I need this information for my new novel, but thought I’d share… by The Society of Procrastinating Linguists


  1. Thank you. That works for me, except… being a TR is hard work. Literary criticism takes as much effort as writing good prose because it uses the same creative process. That’s why an agent won’t give feedback unless she has already decided to represent you, because she thinks she can sell what you’ve written but what you’ve written still needs work as all manuscripts do. So, please don’t do it unless you a) have the time and b) are truly motivated. When you’re ready please contact me so I can tell you what I’m looking for. You can use my contact form or gmail; my name with a dot will work.

    • I wouldn’t do it unless I was motivated and had the time. I would never sell you short that way. That is why, for now, I have to pass, but will notified you when I am able.

  2. Hello Susan,

    Thank you for following me. Perhaps in time I’ll persuade you to become a TR. I’ll be happy to read, and comment, some of your stuff: A Strangled Rose perhaps? I want to thank you and choose to do so at this post, primarily because it appears that we two write in the same genre, both of us are trying to get published and because as a math-trained nerd I’ve had a problem with DNA forensics ever since the Roslin Institute in Scotland cloned Dolly the sheep. Dolly, BTW was named after Dolly Parton because, as Ian Wilmot, her virtual dad asserted, the donor cell used to create Ms Dolly the sheep was derived from a mammary gland cell.

    As this post says there is a one in a million chance that a specific DNA sample belongs to a specific individual. That apparently high order of probability makes for convincing evidence that a person possessing that nearly unique DNA committed the crime where the DNA sample was found. But does it? Is one in a million unique enough particularly where capital punishment is practiced? That’s why I emphasized the word nearly.

    Consider the following: If there are only about a million permutations of the four simple proteins (Guanine, Adenine, Thymine, Cytosine) that constitute a DNA sequence, then in a world of 7 billion there are about 7,000 people walking around with exactly your and my DNA. Identical copies genetically of us. If we limit the discussion to people living in the U.S., then there are about 340 identical copies of us. They won’t all look exactly like us because that population will be age-distributed, but if we found one, say a ten-year-old, she or he depending on whether we are talking about you or me will be exactly like we were when we were ten, baring some environment-caused physical anomaly. This has interesting implications in writing about DNA in our preferred fiction genre. Indeed, Follett tackled the issue in his The Third Twin.

    Suppose someone commits a capital crime and the only evidence the police have is a DNA sample found at the scene. It’s a perfect crime planned down to the last detail except the killer left his DNA. He has an absolutely unshakeable alibi; he was hundreds of miles away at the time and has the evidence to prove it. Without any other incriminating evidence the killer’s lawyer argues persuasively using the mathematics of probability that someone else could have committed the crime. That one of those other 7,000 could be the guilty party. Again, without other evidence it would be up to the jury to decide if one in a million is sufficient to meet the prosecution’s burden of proof. It’s a better argument than OJ’s glove. I keep expecting any day now to read about some smart lawyer getting his client off using this argument.

    When I read about Dolly I had an idea for a fiction story about Conversations with God. The premise was that God decides when and whether to clone someone based on a series of interviews he conducts with the subject’s soul, when it arrives in the hereafter, be it heaven or hell, since God presides over both. God conducts an examination of a person’s life to try to understand why the soul did what it did in life. God does this because he is concerned that the clone might behave in exactly the same way as the soul undergoing examination. He might tinker with the DNA sequence to avoid another life with the same behavioral proclivities. Why make another Hitler or a Nixon or a Kissinger if a little DNA tweak can undo God’s earlier mistake? It was great fun coming up with all sorts of scenarios where a person is forced to face his actions, even by a non-believer such as I. Fortunately, I gave it up when I realized I was pontificating about stuff the world’s thinkers have been struggling with for thousands of years.

    Thanks again for visiting and following.
    Thomas Docheri

    • You make some interesting arguments. Fascinating stuff. To think we have that many dopplegangers out there… creepy. I would be happy to TR some of your work. However, right now I am working diligently on my new novel and don’t have the time. But I will shortly, perhaps the end of the month or beginning of April. If that works for you, great. I’ll look forward to it.

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