Sue Neill-Fraser case contradicts formal logic, analysis shows – part 1

In the 2010 trial of Sue Neill-Fraser, there was an absence of evidentiary proof for establishing the Major Premise of the crime – an essential fact for a valid inference of guilt, writes BENJAMIN DEAN,* in this 3-part analysis of the case applying formal logic#. Part 1- no proof of death

SUE NEILL-FRASER, now entering her 12th year of incarceration, has been granted the Right to Appeal her 2010 conviction for having murdered her partner Bob Chappell, on the couple’s moored yacht, on Australia Day 2009. (The appeal hearing has been delayed due to COVID19 travel restrictions.) Three judges will evaluate whether ‘new and compelling evidence’ proves a Miscarriage of Justice.

However, what remains compelling about the conviction of Sue Neill-Fraser is that the guilty verdict contradicts the rules for a valid inference in formal logic. And since a contradiction renders the conclusion false, the State of Tasmania neither recognised the essential premises necessary to validly infer guilt in this trial, nor presented the necessary evidence for establishing these essential facts. And by convicting Sue Neill-Fraser, the State of Tasmania, has effectively abandoned the democratic obligations to the principles of equality in law, in a nation that is a signatory to UN Convention on Human Rights.

no proof of death

In August 2009, when the Tasmania Police, with the endorsement of the Director of Public Prosecutions, charged and remanded Sue Neill-Fraser for murdering her partner Bob Chappell, the State of Tasmania held insufficient evidence, as revealed at the October 2010 trial, to establish whether Bob Chappell was dead, let alone prove with evidence his manner of death as murder. That is, there was an absence of evidentiary proof for establishing the Major Premise of the crime – an essential fact for a valid inference of guilt.

In contrast to the trial transcript in which the words murder/s/er/ing/ed and kill/er/ing appear some 350 times, the Crown presented to the jury, no body, no eyewitnesses to a murder, no confession, no murder weapon, no established motive, and no forensic evidence that could rationally eliminate all competing hypotheses for establishing why Bob Chappell had disappeared from the Four Winds yacht, on Australia Day 2009. As expressed by legal academic, Dr Robert Moles of Flinders University, there was “…no compelling evidence to show that Bob Chappell is dead, let alone murdered”1.

In explaining this absence of evidence for establishing the Major Premise of the charge to which Sue Neill-Fraser was Commanded by Authority to answer, the former Crown Prosecutor, Tim Ellis SC, in the July 27, 2015, edition of the Australian Women’s Weekly, suggested; “It was not and is not essential to the valid conviction of Ms Neill-Fraser that the prosecution produce a murder weapon or prove a manner of death”.

However, the Crown Prosecution’s appeal for validity to support this conviction, contradicts formal logic, namely the rule for a valid inference modus ponens (if p, then q). Whereby, one fact as the Major Premise (p) MUST be proven with sufficient evidence as true, before it is rational to infer another fact to know if ANY perpetrator (q) exists, as a rational conclusion. That is, to know whether or not, ANY Perpetrator/s (q) exists, the truth value of this fact is logically conditional on whether the premise of the crime (p), has been established with sufficient evidence (or not).

In the absence of evidence to know if Bob Chappell is dead, let alone murdered, then ALL people are innocent is the valid conclusion in formal logic.

The result being that the charge and remand of Sue Neill-Fraser in August 2009 was arbitrary because it lacked a valid reason, by contradicting the rule modus ponens, and therefore was not rationally possible for the Tasmania Police, or the DPP to logically know the existence of ANY perpetrator to the crime of murder. The action violated Article 9 of the International Covenant on Civil and Political Rights. The Burden of Proof, could not logically be met by modus ponens, and therefore no valid reason existed for arresting Sue Neill-Fraser (or ANYONE) for the murder of Bob Chappell in August 2009.

The Tasmania Police investigation was deficient and lacked sufficient evidence necessary to establish the major Premise for the Crime, albeit Tasmania’s justice system remains satisfied with a 23 year sentence for Sue Neill-Fraser, to a crime yet to be established in evidence.

Consequently, what is compelling (in a bad way), is that the conviction of Sue Neill-Fraser has effectively normalised a legal process in the State of Tasmania, in which the premises necessary to validly infer guilt, are now being considered not necessary to be established in evidence in criminal cases, by either the Tasmania Police nor the Tasmanian Courts.

How are people equal before the court, if the standard of proving guilt Beyond a Reasonable Doubt, is accepted by the Court, but at the same time inherently doubtful due to the contradiction to the most basic of rules for a valid inference in formal logic.

How is the standard for the presumption of innocence being upheld by the State of Tasmania, if a crime is not required to be established with evidence? It is rationally not a fair court, if anyone can be sentenced to imprisonment, for a specific crime, yet to be established in evidence? Reason, it appears, is not available as a defence to those defending a criminal charge in Tasmania’s Courts.

logic as necessary standard

This case dictates an urgent need for overhauling Tasmania’s legal system. When Nicholas Cowdery QC, the former NSW director of public prosecutions, gave reasons not to prosecute Chris Dawson for the murder of Lyn Dawson2, and those reasons logically contradict the Tasmania DPP decision to prosecute Sue Neill-Faser, then Australian Law is in need of adopting an explicit model of logic as a necessary standard to justify decisions as rational, and not based simply on belief. While the Tasmanian Government continues to waste this crisis by expressing full confidence in the State Legal System, they are complicit in the continued violation of fundamental Human Rights, allowing the propagating of these errors in other Tasmanian criminal trials, which is effectively undermining Australia as a legitimate democracy.

# Formal Logic can be described as the science for a valid inference, and Aristotle is generally considered the Founding Father. Formal logic has traditionally focused on deductive (either true or false) reasoning. Validity is related to the structure or form of an argument, and not concerned about the content/premises of the argument form. In an argument, if the content (or premises) are true statements, and the form is valid, then the argument is considered sound, and the conclusion can be guaranteed true. Without this mathematical precision in formal logic, modern computing could not exist.

Benjamin Dean

* Benjamin Dean observed this trial at the Supreme Court of Tasmania in October 2010 and has followed the case ever since. He has a BSc, having studied the natural sciences and computing. He has a strong philosophical interest in cultural epistemology, and its evolutionary advantage.


  1. Dr Robert N Moles ACII (UK) LLB (Hons) (Belf) PhD (Edin), Adjunct Principal Researcher, College of Humanities, Arts and Social Sciences, Flinders University, South Australia. – review of Shadow of Doubt, 16 July 2013 – Bob Moles’ review Shadow of Doubt[Sue Neill-Fraser case, Tasmania] “ … no compelling evidence to show that Bob Chappell is dead, let alone murdered. “ p1. Accessed 24/08/20.
  2. Nicholas Cowdery QC, former NSW director of public prosecutions, giving reasons to not prosecute Chris Dawson for the murder of Lyn Dawson. “Without a body, without knowing first of all whether in fact she is dead, without knowing secondly if she is dead, how she died, it’s very hard to mount a case of a reasonable prospect of conviction just on motive and the undefined existence of means and opportunity. That makes it very weak,” accessed 24/08/20

Part 2 will be published on Friday, September 4, 2020

Part 3 will be published on Sunday, September 6, 2020

There is a disturbing parallel to this in NSW with the Robert Xie case. Xie is awaiting the Court of Criminal Appeal’s judgement (heard June/July 2020) arguing against his 2017 murder conviction, which was also a circumstantial case, also lacked evidence to place him at the crime scene or connect him to the crime and thus also contradicted formal logic.

Briefing on the Robert Xie case


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16 Responses to Sue Neill-Fraser case contradicts formal logic, analysis shows – part 1

  1. Garry Stannus says:

    I didn’t comment on Benjamin’s articles when they were published as I didn’t see that his essential thesis was necessarily valid. Probably I wondered whether it was an attempt to bring formal logic to bear when the bases of our system of law are precedent and statute.

    I didn’t have the time to fully take in and properly respond to Benjamin’s argument. I don’t have that time even now, but let me outline a few of my thoughts:

    The absence of evidence is not evidence of absence. That is, though an accused is not identified as being present at the scene of a murder and likewise is not seen doing the murder, yet the murderer has in fact committed a murder. For ‘light’ relief, I reference Agatha Christie’s ‘A Murder is Announced.

    You see, Benjamin’s first article put me offside with all its talk of modus ponens and of p and of q and of q not being valid if there was no sufficient evidence for q – don‘t quote me though, I’m just articulating my thoughts …

    I’m thinking that Benjamin’s modus ponens and its relative modus ponendo ponens as being just a fancy way of saying that argument by assertion is not sufficient for a proposition to be accepted. Rather, the assertion p needs to be supported by appropriate evidence.

    [That’s a good and handy word … ‘appropriate’: it can get you out of any situation when you can’t actually specify the actual criterion justifying viewing particular evidence as credible/factual/etc.

    I continue with Benjamin’s

    ”In the absence of evidence to know if Bob Chappell is dead, let alone murdered, then ALL people are innocent is the valid conclusion in formal logic.”

    This doesn’t look right … I mean … what is his p?

    I mean that is just not valid. We are back at the starting point … the absence of evidence of a murder is not evidence of an absence of a murder, nor indeed, is it not evidence of an absence of a murderer. The absence of evidence to demonstrate the fact of a murder is not evidence to conclude that a murder has not taken place that no one has murdered Bob Chappell.

    Bertram Russell – was it? – confronted a similar issue when he posited for the sake of argument a tea-pot in orbit around the sun … somewhere out past Mars or Jupiter. How can you disprove the existence of a ‘Brown Bettie’ teapot somewhere out there in the planetary region far beyond us?

    For those with a few extra minutes to kill, I will share with you an afternoon chat I once had with Russell on the subject of Brown Betties:

    [If what Jack said about the existence of foxes in Tasmania was true, then Russell must have had more than one teapot].
    Last time Bertie and I drank tea together, I distinctly remember him saying how funny it was that he couldn’t prove the non-existence of something which didn’t exist. You see, we were in his drawing room, taking tea one winter afternoon. I’d complimented him on the gratifying and invigorating flavour of the Assam and he’d replied that it was not just a function of the leaf, but also of the pot. I recall him smiling after we’d both first sipped and he, putting down his cup, exclaiming that there was not in all of creation a pot finer than his own Brown Betty.
    So, more from politeness than interest, I’d asked him how was it that he could know such a thing. How could he, of all people, know that there was no other tea pot ‘out there’ that was better than his? For you see, Jack, he’d gained something of a reputation as a philosopher, and I was anxious to see if he’d give away a few trade secrets. I’ll never forget that wickedly winking face he turned to me, and his words, heard by no one else but myself:
    Garry, good friend! Is it not enough that you share with me the contents of this best of all possible cups? Can you not be content in the knowledge that my Brown Betty beats all comers? For surely, Gazois, (a usage that some bestow on me) (for surely) there can be no tea pots better than this that stands before you?
    Well, it seemed to me that the opposite was equally possible, and so I mildly put it to him that ‘conceivably’ there might just be a tea pot out there, somewhere, maybe even floating in space, that could produce a better brew, than his Assam in a Brown Betty.
    Bertie! says I. How do you know that there’s not a better pot, somewhere ‘out there’, in the ether, doing countless laps of the sun? Some superior pot, let us call it, for the sake of utility, ‘Black Betty’. Let us imagine it’s out there now, somewhere past Saturn and doing laps, just waiting for the moment of its discovery to arrive.
    Pigs trotters, Gazois! How on earth could there be a Black Betty beyond Saturn?
    To which I replied, Well then, just because you can’t see it doesn’t mean it doesn’t exist!
    To which he replied, Just because no one can disprove your belief, it does not make it true.
    To which I replied Ca va sans dire, mon cher, and what is good for the goose is also good for the gander, is it not?

    To which he replied, Steady on Garry, you know, I’m sure you think you’re the King of France, the way you do carry on sometimes.

    Tempers were becoming frayed, so I sought to conciliate: Surely Bertie, it is also true that ‘just because no one can disprove your belief’, it does not make it false!

    More tea? said he, stalling for time, while collecting his thoughts. I accepted with a smile and a nod of the head. As he stood before me, with Brown Betty, his best of all possible tea pots in his hand, he frowned with concentration and then his customary humour returned, bringing back with it his vagrant smile:
    I should think, Gazois, (leaning down towards my emptyish cup) that it would be a ghastly place to try and pour a cup of char, don’t you know? How about moving your imaginary (I was not insensitive to his cut) Black Betty a little closer to home, say, hmmm (and pouring), somewhere between our own dear planet and that of our warlike neighbour. We’ll hide this hypothetical pot far enough away so that we’ll never find it.

    I was glad that Bertie was part way to seeing reason while in my mind’s eye I could yet see my Black Betty somewhere in the asteroid belt, where it would never be found. However, before I could say so, my cup nearly ‘ranneth over’ and he – Bertie – impishly withdrew the pot:
    There, Gazza, the matter is plainly obvious. By any reasonable reckoning, a pot in the hand must be worth two in the void! And yet you claim only one and can not even show it to me. Indeed there are some who would go so far as to suggest that your absence of evidence is itself evidence of your pot’s absence. I for one would not go as far as that, but I could hardly disagree with your teapot proposition. Manifestly, not only is it not wrong, it is not even right!

    At which point the bell rang and I heard James’s measured tread, then the creaking of the door. Cheery voices were heard in the hall, then deft steps taking the stairs two at a time. It was only moments before Karl and “ Surprise! Surprise! – Wolfie burst in. The day was becoming more interesting by the moment…

    In all probability, we’d need pots both brown and black. I smiled at the thought! And yet the question remained: Did the best of all possible pots exist? And where/how could it be located?

    • andrew says:

      All I wish to say is that if for the conviction of Sue Neill-Fraser, a circumstantial case, the prosecution relied on the the ‘strands in a cable’ proposition viz evidence, it is obviously an unreliable legal construct.

  2. Stephen Berry says:

    Lets not forget guys, that apart from now having Megan’s statement, at the time of the trial we also had and still do have, two different dingy’s not belonging to the Four Winds tied to it that afternoon. I have for a long time thought that Bob is not in the Derwent, because that doesn’t fit with any of the alleged police facts. The fire extinguisher weighed 4-5 kgs making it a float and incapable of being used as ballast. Plus carpet tiles, canvas and rope as alleged by the prosecution would also float and this was never tested by the police. As Sue pointed out to the police that ropes had been cut, yet the police never investigated if any rope was missing or tested the cut ends for DNA. They also did not try to match the ends. When the Four Winds dingy was taken to the laboratory for testing, no blood could be found.
    Now as Colin points out its very strange that a guy should walk into the police station and pont an allegation at Sue and also that there has been many strange accidents at sea, yet in this case there is overwhelming evidence that something more sinister took place that afternoon or evening and that the two dingy’s and those who used them have a part to play in what happened to Bob.

    Now the older I get the less I believe in fairies at the bottom of the garden so that strange out of the blue and opportune telephone call to Sue on the evening of Bobs disappearance from some guy who has had an interest in Bobs daughter does not sit well with me!

  3. Colin McLaren says:

    You are right to highlight that there is ‘no proof of death’, the prosecution failed to establish that a homicide really took place. Indeed, if you study the crime scene – I spent days on the yacht, post factum, as did veteran Homicide Squad detective Charlie Bezzina – and all that could be gleaned was a couple of teasing clues. Such as minimal blood spatter in the area of the wheelhouse and in the cabin, on the sofa, vertical blood stains, immediately below a skylight hatch. There was not the usual signs of a violent confrontation, nor were there any weapons located. Nothing consistent with the owner of a luxury yacht being set upon, killed and disposed of in the swift moving currents of the Derwent River. Reason being? The yacht was partially submerged, flooded. Indeed, a seasoned detectives’ worry, confronted with this sort of a scene would be in defining whether it was a crime or an accident. You could toss a coin on it. EG: Bob Chappell, choosing to sleep alone on the yacht that night to undergo repairs, was known to be clumsy. Also known was his intention to fix a water pipe. In so doing, perhaps he cut himself badly (the toilet pipe was cut) and panicked. Without his mobile phone (fact) perhaps he grabbed the EPIRB warning device (it was missing) and signaled for help, before falling overboard (it was pitch black) and his body was lost to the open ocean, downstream. Nautical accidents are known to be tragically simple.
    However, two issues came into play, before Police could file away their paperwork; firstly, there was a treasure trove of DNA evidence decorating the yachts galley and on its deck. Someone had vomited over the scene. And, secondly, a man with a checkered past walked into a police station and told a fantastic story that Sue Neill-Fraser was a killer, not a placid house wife. His story offered a solution, more compelling than a simple accident. Whilst police started to sharpen their gaze on Sue Neill-Fraser the methodical forensic work circling the DNA took a backseat. Many of the collected samples went untested (they still haven’t been tested) as police built a case around a grandmother. The rest we know.
    It’s correct that you shine a torch on the way our justice system has been heading; repetitive use of prejudicial language that taints an accused: 350 times the prosecution labelled Sue Neill-Fraser a murderer, killer etc, to a jury hungry for facts. By trial end, her water was forever muddied by slander, not evidence, because there was little of that. Yet, truth be known, no one could say (in 2009-10) with any degree of certainty how Bob Chappell died. Accident or otherwise. We know differently now!

    • andrew says:

      Former detective Colin McLaren, has written an investigative book, Southern Justice, which explores the police failures in the Sue Neill-Fraser case. See our report here:

      • Ben Dean says:

        Thanks for commenting. I bought and read your book. I cannot imagine how anyone, after reading the book, could not question this case and be very disheartened about those in charge of Justice in Tasmania. It is ironical how much expertise beyond ‘Tasmania Justice’ that this case has attracted. In a different world in which integrity, statesmanship and a conscience for social justice was a natural attribute of authority, then it would be a spectacular upgrade to harness this expertise to bring Tas policing and the court system into the 21st century. Envy of the world. But no, just stone wall – deny, delay, do nothing.

  4. Joana Cubillos says:

    Excellent article. My biggest question goes to the Governor, Professor Kate Warner. The only person above the Crown prosecution is her. Yet she has conveniently ignored this issue, as part of the elite group of lawyers in the state, which constitute the so called Legal system. How is it possible to be unbiased in a Court of Law when they’re all mates? She would have received hundreds of emails, and has responded to none.

    • Ben Dean says:

      Thanks Joana for commenting. Funny enough, I was called up for jury duty the other day. The only guidance given to us was to be impartial and use common sense! Ignoring that fact that a large percentage of all people have very poor critical analysis skills, I’m still struggling to see this simple criteria within the main actors of the court system.

  5. Keith says:

    So 2,000 AFL players, wives, girlfriends, children and officials can go to Queensland for work, largely from Victoria, yet the Tasmanian Government cannot see their way clear to allow a couple of dozen people involved in this case into their state to clear SNF’s name and get her out of gaol.
    There is no excuse for this case not to proceed and to hide behind the virus is a disgrace.
    Justice delayed is justice denied.

  6. owen allen says:

    Great work.
    Every comment is a vote.
    United We Stand Divided We Beg.
    Ask Robin the Hood, or Tolpuddle Martyrs. That is where Tasmania is at.
    I lived in the Midlands of Tasmania.

  7. Rodger Warren says:

    No one can be safe from prosecution in Australia until Sue Neil-Fraser is released from Jail.
    I refuse to go to the beautiful Tasmania until Sue is exonerated.
    A Criminal Cases Review Commission is badly needed in Australia.

  8. Munro Woddy says:

    In recent times, throughout Australian Courts there has been a shift from establishing in evidence the important elements of a case in circumstantial cases, to simply discrediting the charged by painting them to be very, very bad people, and therefore influencing the jury’s decision making to ignore any claim of innocence the accused or the defense are making. This is nothing more than a procedure in the cultivation of suspicion. And then a totally uninitiated jury, with no requirement to be critical thinkers are demanded to decide on another’s freedom. In no other profession, other than law, are rank amateurs invited to assess unfamiliar evidence and write the conclusion. Politicians around the world know the power of character assassination (ad hominen) of opponents and how easy enough the public can be manipulated (the power of terror) by this technique, and now it has progressed to the courts. Respect for law? What a total joke. The court is hostile, irrational and a dangerous place to find yourself.

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