So, I’m giving this whole @threadapalooza thing a try, on the topic of How Not To Think Like Sherlock Holmes. Here goes!

1. So, Sherlock Holmes is a very particular archetype of intelligence, and it’s a very problematic archetype for a few different reasons. I’ll start the thread by laying out the key elements of the archetype, and then talk about why they are problematic.

2. His moniker of ‘Master of Deduction’ suggests that the arguments he gives are deductive ones; in other words, provided the premises he puts forward are true, the conclusions are also guaranteed to be true.

3. This approach to reasoning can be summed up with the famous phrase “when you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.”

4. Holmes is very particular about what he bothers to learn and to remember. The most famous example from the stories is that he doesn’t know that the earth goes round the sun.

5. This fact has no place in his ‘brain attic’, which is only used to store, in perfect order, knowledge that is relevant to his detective work (although, admittedly, it also presumably contains information about playing the violin.)

6. Holmes is essentially a lone genius. Whilst Watson is not exactly dead weight, he’s mainly there to be pontificated at, and it is understood to be Sherlock’s intellect that actually solves the cases.

7. His problematic or transgressive behaviours (rudeness, dismissiveness towards the intellect of other people in general and to the police in particular, recreational drug use) are tolerated by those around him, apparently on account of his remarkable intelligence.

8. So, let’s start the critique by looking at the actual reasoning processes he puts forward. I’m going to use BBC Sherlock for this, from the clip here:

9. I won’t go through every point of the argument here, but suffice it to say that the argument does not qualify as deductively sound. Alternative explanations for the observed evidence abound. It’s fun to find them and I suggest you have a go.

10. My favourite example is at 2.36, where having confidently said ‘under her coat collar is damp too, she’s turned it up against the wind’, he immediately turns around to reveal his own upturned collar, clearly styled in this manner purely to look cool (which to be fair it does)

11. Sherlock Holmes proceeds from this point as if he had eliminated, as impossible, all other lines of enquiry, when in fact he has not. He has therefore prematurely closed down plausible lines of enquiry (notably Anderson’s, who gets a door slammed in his face.)

12. I've viewed this clip with students, who often initially had a very strong impression of Holmes’ capabilities, and then a much weaker one once they were asked to come up with alternative explanations for the evidence. At which point, I asked: “Why did you believe him?”

13. The answers I’ve had have included:

‘He was speaking really quickly so he seemed to know what he was talking about',

‘He’s very confident, he just sort of sweeps in and takes charge',

And even:

'He’s really tall'(?!)

14. The last of these was only half in jest and got us into the idea of how Sherlock’s appearance might affect how believable he is perceived to be. Yes, he’s tall, he’s good-looking.

He’s also well-dressed and well-spoken in a manner that indicates wealth. He might be believable due to competence, sure, but he is also believed due to certain social privileges he carries: privileges of gender, class, and race.

16. In particular: this is a man who regularly uses both heroin and cocaine and has an antagonistic relationship with certain members of the police force. Frankly, a black Sherlock would likely be in prison.

17. This connects up to a concept developed by Miranda Fricker in Epistemic Injustice: Power and Ethics of Knowing. To suffer an epistemic injustice is to be ‘wronged in one’s capacity as a knower’.

18. One example of this is testimonial injustice, where your testimony is doubted for epistemically irrelevant reasons which connect to your membership of a marginalized group.

19. Fricker is primarily interested in epistemic injustice as an extension of social injustice more generally. She acknowledges, but does not take particularly seriously, the reversal of this situation...

20. ...that reversal being where your testimony is too easily believed by those around you due to epistemically irrelevant reasons which connect to your membership of a privileged group.

21. My instincts are different. If you are unjustifiably believed because of your privilege, then you risk having false beliefs reinforced and passing them onto others. It may lead you to lack appropriate standards of self-appraisal in the future.

22. Believing Sherlock when he is wrong, or rather not bothering to treat his argument with an appropriate degree of skeptical engagement before believing it, may not be a social injustice, but it is an epistemic injustice of sorts, because he will be less wise for it.

23. It’s also worth considering something which lies kind of at the border of ‘marginalization’, and that is the skill and the manner with which one is able to present the argument itself.

24. This issue is very well expressed in the following poem by Wendy Cope: https://poetryspotlight.wordpress.com/2014/07/05/he-tells-her-wendy-cope/

25. Clearly the situation Cope illustrates here is connected to social justice and particularly to gender. The manner with which the nameless ‘she’ presents herself is archetypally feminine and emotional.

26. She argues ‘fiercely’ and ‘long’, she (at least according to the questionable other party) ‘yells’. She, unlike her opponent, has not ‘learnt to argue well’ and therefore her arguments are ‘unsound’. Yet, what she believes is true.

27. Cope’s nameless ‘she’ is unable to present her evidence in a manner which is believable to her opponent, regardless of the actual content of the argument. Anderson, to some extent, finds himself in a similar position:

28: Anderson: ‘She’s German. Rache, German for revenge. She might be trying to tell us something…’

Sherlock: ‘Yes thank you for your input’ [slams door in Anderson’s face]… Of course she’s not. She’s from out of town though…. So far so obvious.'

29. To be clear, Anderson isn’t suffering the systematic epistemic injustice that Wendy Cope is portraying: he is not disbelieved due to his gender. Nonetheless, his testimony is ignored due to irrelevant factors.

30. He lacks Sherlock’s dominance, his confidence, his style, and therefore his contribution is ignored. In this sense, an epistemic injustice is committed against him.

31. So. Much of Holmes’ plausibility might arise from epistemic privilege. But surely his basic approach to reasoning is in and of itself excellent?

32. That approach can be summed up in the famous phrase:
‘When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.’

33. Well, er... This is known as the Holmesian Fallacy, and there are a number of ways in which it is wrong.

34.
A. It requires you to identify every potential explanation for the observed phenomenon,
B. It requires you to demonstrate that all but one of those is impossible,
C. It claims that we are more justified in believing highly improbable statements than impossible ones

35. Starting with A: certainly we can identify a number of the more plausible potential explanations for something and then try to rule some out, and this is perfectly good investigative practice. We cannot, however, identify them all.

36. We don’t have that degree of information or imagination (certainly not as individuals, but even as communities). Also it might be something of a waste of intellectual resources to try, since some of the potential explanations will be wildly silly.

37. B also can’t be done. Proving something to be impossible is not only a difficult task, but arguably an impossible task for empirical claims (yes yes, recursion, hush, the point stands).

38. To be trite about it, it is not even logically impossible for the killer to appear out of thin air and then disappear again. It is merely physically impossible. But the thing about physical impossibilities is they aren’t as impossible as logical impossibilities.

39. Aristotle wrote about Thales, who observed the interactions of lodestones (or what we would call ‘magnets’) with iron. Since it is clearly impossible for inanimate objects to move other inanimate objects, the stone must be imbued with some active force.

40. Thales took this as proof that all things were full of gods.

41. Of course it is perfectly possible for inanimate objects to move other inanimate objects if they are magnetic, but Thales didn’t know about magnetism.

42. Not only that, but magnetism was inconsistent with his overall understanding of how the world worked. Really that’s what we mean by ‘impossible’.

43. This isn’t at all stupid, by the way. Susan Haack presents a concept of scientific knowledge called foundherentism, which is intended as a cross between coherentism and foundationalism.

44. Coherentism calls on us to test our beliefs by establishing whether or not they are coherent with other beliefs that we already have.

45. If some new observation isn’t coherent with the established ones, it makes more sense to doubt the particular observation than the established system you and others have put so much work into.

46. After all, it’s more likely that you’ve made one basic mistake, than that you and those you work with have a whole bunch of mutually supporting basic mistakes (or let us hope so, anyway).

47. However. We can’t ignore observation as the foundation of our knowledge. The coherentist approach is only OK if we also keep observing.

48. As and when evidence piles up that the original non-cohering observation wasn’t a mistake, we acknowledge that the established system must be wrong in some way, and put effort into figuring out how.

49. Essentially, it’s not necessarily a point against an idea that the idea is impossible. It might just make it more interesting... And so we come to C. In The Long, Dark Teatime of the Soul, Douglas Adams offers a wonderful and memorable attack on the Holmesian Fallacy:

50. “The impossible often has a kind of integrity to it which the merely improbable lacks. How often have you been presented with an apparently rational explanation of something which works in all respects other than one, which is just that it is hopelessly improbable?...

51. ... Your instinct is to say “Yes, but he or she simply wouldn’t do that.”….The idea that she is receiving yesterday’s stock market prices apparently out of thin air is merely impossible, and therefore must be the case...

52....because the idea that she is maintaining an immensely complex and laborious hoax of no benefit to herself is hopelessly improbable. The first idea merely supposes that there is something we don’t know about, and God knows there are enough of those.”

53. When faced with a choice between accepting a highly improbable explanation and an impossible one, Adams suggests that we might be more justified in believing the impossible.

54. To believe the ‘impossible’ here is to believe that there is something we don’t know about, that there are layers to this that don’t meet the eye; that there are questions we haven’t even thought to ask yet. It demonstrates an intellectual modesty which Holmes sorely lacks.

55. Next up in “project ruin Sherlock Holmes’ reputation”: Holmes tries to think by himself, and this is a terrible idea.

56. The longer way of saying this is that Holmes’ reasoning skills are compromised by his epistemic isolation. This comes in two forms. The first is an extreme degree of specialization, accompanied by a more general ignorance (which he deliberately chooses).

57. The second, connected issue is the social isolation that arises from his ‘solitary genius’ status, which prevents him from benefiting from full membership in an epistemic community.

58. Let’s start with the first issue. In 'A Study in Scarlet', Watson is shocked to discover that despite his extreme cleverness and comprehensive knowledge of some subjects, Holmes is remarkably ignorant about many others - and quite deliberately so:

59. “His ignorance was as remarkable as his knowledge. Of contemporary literature, philosophy and politics he appeared to know next to nothing. Upon my quoting Thomas Carlyle, he inquired in the naivest way who he might be and what he had done...

60. ... My surprise reached a climax, however, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the Solar System....

61. ... That any civilized human being in this nineteenth century should not be aware that the earth traveled round the sun appeared to me to be such an extraordinary fact that I could hardly realize it.” (A Study in Scarlet)

62. Far from being ashamed of this ignorance of general knowledge, Holmes defends it as necessary in order to ensure that he becomes (and remains) knowledgeable about the stuff that is actually pertinent to his vocation:

63. "I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose...

64. ...A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things, so that he has a difficulty in laying his hands upon it...

65. ...Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order...

66. ... It is a mistake to think that this little room has elastic walls and can distend to any extent. Depend upon it, there comes a time when for any addition of knowledge, you forget something that you knew before...

67. ...It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.” (A Study in Scarlet)

68. This extreme devotion to specialization is problematic in that it requires that you know ahead of time whether something will be pertinent to your investigation or not - without learning it for yourself.

69. Now admittedly, this isn’t altogether impossible. We can find out that developing a particular skill or area of knowledge isn’t very helpful for our interests, and decide not to bother with it.

70. But we find this out by asking other people (perhaps those in our profession) if they have found it useful to learn that skill, and then following their advice.

71. This, in turn, requires (a) that we are on friendly terms with a number of other people in our profession whose opinions we respect; (b) that those people have taken it upon themselves to learn about that topic without already knowing whether it would be helpful.

72. It requires others to have taken on a particular epistemic responsibility which you are not taking on yourself. A division of epistemic labour therefore seems appropriate: you learn about A, I’ll learn about B, we’ll regroup and report on whether either A or B are useful.

73. But this whole line of possibility requires that you have peers whom you respect. This doesn’t appear to be the case for Holmes, as Watson learns in The Sign of the Four:

74. "I abhor the dull routine of existence. I crave for mental exaltation. That is why I have chosen my own particular profession,—or rather created it, for I am the only one in the world.”
“The only unofficial detective?” I said, raising my eyebrows...

75. “The only unofficial consulting detective,” he answered. “I am the last and highest court of appeal in detection. When Gregson or Lestrade or Athelney Jones are out of their depths—which, by the way, is their normal state...

76. ......—the matter is laid before me. I examine the data, as an expert, and pronounce a specialist’s opinion." (The Sign of the Four)

77. Sherlock’s high opinion of himself and low opinion of the police force in general ensures that he is unlikely to engage in any significant division of epistemic labour with (what he would never call) his colleagues.

78. Whilst the police force may bring pertinent data to his attention, the interpretation of this data - its transformation into actual insights - is something that he entrusts to himself and himself alone.

79. In the Study in Scarlet, Lestrade proudly announces that he has found a note, written in blood, of the single word Rache. His interpretation of this is:

80. ”...it means that the writer was going to put the female name Rachel, but was disturbed before he or she had time to finish. You mark my words, when this case comes to be cleared up you will find that a woman named Rachel has something to do with it...

81... It’s all very well for you to laugh, Mr. Sherlock Holmes. You may be very smart and clever, but the old hound is the best, when all is said and done.” (A Study in Scarlet)

82. After having mocked Lestrade with his manner and tone of voice, and examined the room in detail, Holmes reels off a list of information about the murderer and then issues this parting shot:

83. “One other thing, Lestrade,” he added, turning round at the door: “‘Rache,’ is the German for ‘revenge;’ so don’t lose your time looking for Miss Rachel.” With which Parthian shot he walked away, leaving the two rivals open-mouthed behind him.”

84. BBC’s Sherlock offers a rather elegant reversal of this exchange in A Study in Pink. As Sherlock and John are ushered into the crime scene by Lestrade, Anderson proudly delivers his insight: “She’s German! Rache, German for revenge. She might be trying to tell us something…”

85. He is interrupted by Sherlock’s brusque “Yes, thank you for your input” and a door slammed in his face. Later, when Sherlock suggests they start inquiries about a woman named Rachel, and Lestrade asks for confirmation “She was writing Rachel, then?”

86. Sherlock replies sarcastically “No, she was writing an angry note in German… Of course she was writing Rachel, no other word it can be!”

No other word it can be...

87. In the version of this where Sherlock Holmes alone is familiar with German, knowledge of German is esteemed, and interpretations of evidence that rely on this knowledge are therefore elevated.

88. (After all, German must be relevant to the investigative process, right? Sherlock would have jettisoned it from his brain-attic, otherwise).

89. But in the version where Anderson also knows German, knowledge of German is devalued, and so too are potential interpretations that rely upon it.

90. What I find particularly interesting in this respect is that a lot of Sherlock’s ‘deductions’ about that scene are based on a forensic analysis of the victim’s wedding ring.

91. I learned from a German-speaking student of mine that if the victim is German, it might not be a wedding ring. It’s on the wrong hand: in (parts of) Germany, the wedding ring is worn on the right.

92. The (possibly false) assumption that it is a wedding ring underpins a lot of Sherlock’s reasoning here, so it would clearly be helpful if the possibility that she might be German is left on the table.

93. Of course, Sherlock turns out to be right. He has the writers on his side, after all. But Doylist explanations aside, he does have a sharper mind and a better track record than Anderson, so the temptation to defer to Sherlock and ignore Anderson is understandable.

94. In the 'Conduct of the Understanding', John Locke articulates why this would be a bad idea. There are, he says:

95. “those who readily and sincerely follow reason, but for want of having that which one may call large sound roundabout sense, have not a full view of all that relates to the question and may be of moment to decide it...

96. This might instruct the proudest esteemer of his own parts how useful it is to talk and consult with others, even such as come short of him in capacity, quickness, and penetration...

97. ...it is not... beneath any man to try whether another may not have Notions of things Which have escaped him, and which his reason would make use of if they came into his Mind." (The Conduct of the Understanding, John Locke)

98. Notice that my criticism of Sherlock was that he tries to think ‘by himself’. This is not the same as thinking ‘for himself’. Thinking for yourself is to be commended: I take this to mean engaging with the evidence, evaluating it, and putting forward original ideas.

99. Thinking by yourself, however, involves deliberately excluding the intellectual input of others. This makes your beliefs less justified than they could be, even if they happen to be true.

100. This applies even though Anderson ‘comes short’ of Sherlock in ‘quickness and penetration’; because whilst intelligence might be a property of individuals, knowledge isn’t.

And that's the lot! I have an online course on 'How Not To Think Like Sherlock Holmes' and I will be setting up new dates soon, so if you’re interested in taking part, pop over to http://www.lisamcnulty.co.uk  and get in touch.