There was an interesting podcast by RadioLab this week concerning the nature of truth that I wanted to comment on. There were a number of stories in the broadcast, as always. One on yellow rain is getting the lion’s share of attention on the RadioLab site for the treatment of one of the guests that many listeners objected to. However, that is not the one I would like to focus on. In fact, I really only wanted to mention the podcast because I thought it was a good introduction to a topic that I find troubles a lot of people.
First, the podcast. I would point you towards the short, “In the valley of the shadow of doubt,” about one of the earliest photographs taken during wartime. In fact, the episode is about two photographs by the same person, Errol Morris, who was documenting the Crimean War in 1855. The two photographs depict the same scene, titled ‘In the Valley of the Shadow of Death’ that depict a road in the Ukraine. In one, the road is littered with cannonballs. In the other, there are no cannonballs on the road, but there are many off on the side of the road in ditches an on the hills.
The question that the photographs bring up is, ‘Which one was taken first?’ That is, did the photographer come upon a road littered with cannonballs that were removed – or did he come across a road surrounded by cannonballs that he moved in order to catch a more interesting shot?
Of course, we can never know.
There are reasons that can lead us to believe one thing or another (personally, I think one argument is stronger) but there is no way to know absolutely one way or the other. This is the real question that the episode brings up, “Can we ever know truth?” This is a very basic question in science. Most scientists agree (I am presuming) that we can never know anything with certainty. We can only rule out unlikely answers and give support to one theory or another.
We can blame Descartes for starting this with his Discourses on the Method published in 1637. He started the trouble by giving us the scientific method, a method for uncovering the way the world worked. In his pursuit of this, he also realized that we cannot really know anything. He admitted only one thing that we are sure of. Cogito ergo Sum. But from this modest beginning, he also built up a structure and assured us that we have to assume that we can trust in at least logic, and that, until there was reason to believe otherwise, we may as well proceed as if the world we see around us does exist – evidence that he read his William of Occam (1288-1348).
Natural Philosophers and scientists have been fairly comfortable with this state of affairs for years. Assume that the theory with the most data supporting it is true up until the point that new data demands a change in thinking. At this point, we are instructed to drop the old idea and embrace the new one until it inevitably is displaced.
But these words mean different things to different readers. Some may read this as, “See, they admit it, they know nothing. And even worse, the are certain that their ideas will be proven wrong sometime in the future.” Others think, “Yes, of course. How else could one perceive the world?” And they’re both right – in a manner of speaking. It is assumed that much of what we know will change over time. But we also have the security of knowing that our understanding of the world is getting better all the time and it is unlikely that with new ideas we will entirely abandon out old ways of thinking. Rather, we expect to tweak this ideas.
And this would all be fine. But there is another school of thought that comes mostly from the journalists. That is the idea that every position / point of view is equally valid. There are a lot of questions that come to mind where I do think opposing ideas have equal value. These are political questions mostly. However, when journalists come to interview scientists about some finding or idea, two (or more) sides often don’t have the same weight of evidence behind them.
If I were to ask you where teeth go after they fall out and are placed under a pillow, you might say, “The parents take them and give the children money.” You might say, “the tooth fairy comes and leaves the money in exchange for the teeth.” I tell my son that the tooth fairy needs teeth because she eats them and couldn’t survive without nourishment.
Not all of these hypotheses are equally likely. I have to admit that I’ve never seen the tooth fairy, but someone must have left a camera out to get this picture…
Back to RadioLab. So, what’s true? Does the weight of evidence make something true? Does it make it more likely to be true? Does evidence mean nothing?
On a deep level, perhaps we never know anything. But I can also say this: data is nature’s voice and sometimes it pays to listen.