Searching for a needle in a vat of hay and acid

I remember watching my first episode of CSI, and I thought how wonderful a vehicle it could be to introduce science to people who otherwise saw it as a waste of their own personal brainpower. The ability to deduce, with enough scientific knowledge of how one thing can affect another, to rewind the clock and produce a streaming video of what must have happened, is attractive to most people. Its an almost godlike sense to understand the world to that degree.


Sir Arthur Conan Doyle, long before CSI, made an art out of this kind of reasoning in writing the most well known Detective novels, ever. From the Wikipedia we learn a bit about the style of reasoning of the legendary Sherlock Holmes:

Holmes's primary intellectual detection method is induction, which Holmes rather inaccurately calls deduction.^[24] "From a drop of water", he writes, "a logician could infer the possibility of an Atlantic or a Niagara without having seen or heard of one or the other."^[25]

The mechanical universe, how one solid object impacts another, has been understood for much longer then that. Tracking, long before formalized science, taught one to know how to read a print in the dirt to determine the type of animal that made it. The size of the sticks that are broken, as well as the depth can infer the weight of the animal. But knowing how intangible objects effect the environment is also useful, what happens when a green blade of grass is broken, and how long does it take to get that way? That information is useful to determine the time that the imprint was made.

Also available at the Wikipedia, is an example of Holmes style reasoning much along the same lines as the ancient tracker...

Sherlock Holmes's straightforward practical principles are generally of the form, "If 'p', then 'q'," where 'p' is observed evidence and 'q' is what the evidence indicates. But there are also, as may be observed in the following example, intermediate principles. In "A Scandal in Bohemia" Holmes deduces that Watson had got very wet lately and that he had "a most clumsy and careless servant girl." When Watson, in amazement, asks how Holmes knows this, Holmes answers:

It is simplicity itself ... My eyes tell me that on the inside of your left shoe, just where the firelight strikes it, the leather is scored by six almost parallel cuts. Obviously they have been caused by someone who has very carelessly scraped round the edges of the sole in order to remove crusted mud from it. Hence, you see, my double deduction that you had been out in vile weather, and that you had a particularly malignant boot-slitting specimen of the London slavey.

In this case, Holmes employed several connected principles:

• If leather on the side of a shoe is scored by several parallel cuts, it was caused by someone who scraped around the edges of the sole in order to remove crusted mud.
• If a London doctor's shoes are scraped to remove crusted mud, the person who so scraped them is the doctor's servant girl.
• If someone cuts a shoe while scraping it to remove encrusted mud, that person is clumsy and careless.
• If someone's shoes had encrusted mud on them, then they are likely to have been worn by him in the rain, when it is likely he became very wet.

By applying such principles in an obvious way (using repeated applications of modus ponens), Holmes is able to infer from his observation that "the sides of Watson's shoes are scored by several parallel cuts" that:
"Watson's servant girl is clumsy and careless" and "Watson has been very wet lately and has been out in vile weather".

 However useful to CSI or Sherlock Holmes, this evidence of circumstance is not a perfect predictor of causation. You may see scratches on a leather shoe, and reasonably infer its origin, but that is in the eyes of causality always a guess. You may see a broken blade of grass along a trail, but to infer that it was broken by the same animal you tracked is guesswork. While you know what can cause the evidence you read, you can sometimes never know what actually caused it.

At the time a change happens, one can observe everything about the conditions where it occurs. But as time goes on, or the less you know about the conditions, the possibilities of what could have caused the change grows. If you see a cat walking across the grass, and know where its footprints land, then you know what caused the broken blade of grass. But as time goes on, the list of suspects (another cat, maybe another person who walked by) grows as the uncertainty grows.

Sometimes looking for causality is like looking for a needle in a vat of hay and acid. What you expect to be an object of a certain shape and size, is only there for a moment before it is dissolved away into the universe around it. Add to that the obscurity of hay around it, and you can't clearly see the needle even if you were there before it dissolved away.

David Blankenhorn recently replied to someone who was looking for just such a specific shape of a needle when he mentioned how difficult it is to peer through a cloud of related possibilities.

My worry is that, 20 years from now, marriage as a social institution in the U.S. will be significantly weaker than it is today, including much higher rates of unwed child bearing and non-marital cohabition, which in turn will mean that each year a lower and lower proportion of U.S. children are living in a married home being raised by the father and mother whose union created the child.
And some of us (if we are still around!) who will be horrified by these anti-child facts will look back and ask ourselves, What went wrong? What caused this sad result? What could or should we as a society have done differently to prevent this degree of de-institutionalization of our most pro-child social institution?
And some will say, it was the sexual revolution and the pill! And some will say, it was no-fault divorce! And some will say, it was the welfare state! And some will say, it was our changing moral values! And some will say, it was ART, cloning, sperm banks, and the [commercialization] of child making! And some will say (I will be one of them, if I’m around), it seems to have been at least in part all of these things, plus the legal [redefinition] of marriage from man woman to two persons.

There may be may reasons to debate the causality of what had happened. As someone recently pointed out in our comment section, "How were we supposed to know?!" so quickly follows "You can't prove this change will cause harm". For someone to buy into Blankenhorn's vision of the future as a rallying cry for action, they have to 1) see the same trend and 2) have reason to fear it. But for someone to brush it off, all they have to do is demand to see something that looks like the needle they are looking for instead of trace elements of evidence.

And we — I am sure, at least, that I — won’t be able to produce any such body of objective measurable scientific proof. (Or at least, any body of proof that will strike you as convincing.) And the main reason why, is that a social change of this nature and magnitude can’t be measured for causation in this way — no matter how hard you try, you simply can’t go back with the tools of social science and empirically disentangle all the myriad possible causal factors in a complex social transformation of this sort and say with any level of confidence that “factor X caused X proportion of the social change in question.” It simply can’t be done.
And so, therefore, we’ll never really know, either way, the degree to which gay marriage will have contributed, or not contributed, to the (some us will say) harmful deinstitutionalization of marriage in the US.
Meanwhile, for US children, while you and I and others were droning on in these debates, things will have gotten dramatically worse, as far as their living arrangements and the likelihood that they know their parents. And I don’t think that they will be comforted or helped in the slightest by the fact that you and I and others won’t be able to tell them, or agree on, exactly why this has happened.
To repeat: This not a prediction. Anyone who would make a “prediction” of this sort, either way, is, in my mind, not being very intellectually serious. And no, I have no measurable, objective whatever blah blah. But this is my worry, my concern, my fear.

 When I created the "On Lawn Quadrangle" that is my own platform for the debate about marriage, I rested on many of the same inferences that might be understood by a tracker, or Sherlock Holmes. As one knows that bending a blade of grass breaks it, I noted mechanisms that to me would produce results like Blankenhorn suggested. I noted tenets that were presented as part of neutering marriage that would influence people to make bad choices.

[T]enets [that] might help one conclude that it is okay to abandon a spouse or child who you helped create together because anyone's love is as meaningful to them as yours is. Or one might be encouraged to conclude that abandonment is a good thing for you, that what sexual freedom you may want to engage in is more meaningful than the relationships with said spouse and child. Even worse, that marriage is meant to recognize such sexual freedom, but not the responsibility you have in procreation.

Like with Blankenhorn's vision, pointing that out can only influence people that see the results of those tenets and even the tenets themselves, as a bad thing. But I'm uniquely disappointed when people who wish to neuter marriage refuse to discuss the merit of those tenets -- assuming they disagree on their value or capacity for corruption in the first place since they seem to uniquely avoid tipping their hand on that topic.

One could expect them to say those are not tenets of neutering marriage. Or one could expect them to say that those are really positive results. But instead, they say they don't want to talk about it and kindly (but sometimes not so kindly) take that needle, stick it in a vat of hay and acid, and ask me to find it to prove it existed in the first place.

Such is the comedy.