The Jelly Roll of Truth

What do elephants have to do with cakes...? Mary Midgley has the answer

“Slicing the world in different directions reveals different patterns. Swiss rolls (or Jelly rolls), sliced downward, have a spiral structure. Sliced across, they have stripes. Stripes are not reducible to spirals, nor vice versa, and will not become so by further analysis. Both are real, and the two patterns can be related if we understand the relation between the two slicing angles.”
- Mary Midgley, Beast and Man

If ever there was a perfect image of how irreconcilable differences between our worlds might transpire to be the result of circumstances rather than substantial errors, it is Mary Midgley's ‘jelly roll of truth’. As a Brit, I prefer to use the term ‘Swiss roll’ for this baked confectionary, but I’m mindful that ‘jelly roll’ might be the more widely travelled name. Either way, the elegance of this metaphor is that it immediately conveys that sense of the underlying rationality capable of uniting two observations that at first glance seem to be utterly incompatible.

Of course, the precedents behind this image are far older. The Hindu traditions were the first to speak of the blind seers and the elephant, although the Sufi poet Rumi remarks fondly upon this tale, and plenty of other traditions have found the wisdom in it. If you have somehow managed to avoid this parable, the essence is that since they have never seen an elephant, each thinks it is something different. The one grabbing its tail believes it to be like a snake, the one grabbing its tusk believes it to be like a spear and so on and so forth. The Discordians have an amusing take on this tale in which blind elephants, feeling the world with their massive feet, conclude that humans are like pancakes.

However, Midgley’s ‘jelly roll of truth’ not only captures the wisdom in the Hindu folk tale, it takes it in a novel direction. Key to the tale of the blind seers and the elephant is that none of those touching have ever seen an elephant, and therefore they can only guess at what it might be like. The jelly roll, however, conveys this ancient wisdom as well as a fresh philosophical perspective highly pertinent to a world where scientific investigation has (in principle, at least) been given especial importance.

If we take one piece of evidence and jump to a conclusion, we risk being misled. We are equally likely to be mistaken if we take two pieces of evidence that contradict each other and assume that one must be correct while the other is false. As Midgley suggests, you cannot reduce spirals to straight lines nor vice versa. What is required to relate the two apparently conflicting observations is an understanding of the structure of the jelly roll. Only when we have this can we understand how it all fits together - and also, when we have that conception correctly worked out, the fact that it can reconcile the conflicting observations is a key part of how we validate the interpretation.

In my correspondence with Mary Midgley, I often remarked upon the apparently effortless way that she managed to come up with such simple shorthand ways of getting at deep truths, something I have strived for in my own philosophical work. But of course, the apparent effortless of these metaphors is deceiving, for it is the willingness to try other, less successful representations that paves the way for those that succeed in their intentions. This is a lesson that applies to all fields of human endeavour - the simple solutions are not necessarily the quickest to develop. It is especially true of the art of interpreting scientific data.

There are many mistakes that flow from the unique ways each of our worlds slices the ‘jelly roll of truth’. We could take the fact we see spirals as proof that the truth is spiral-shaped. We might even slice again and again, convincing ourselves that it can only be spiral-shaped, since no other shape appears! Yet somebody somewhere is looking at straight lines, and every slice they make comes back with straight lines! The lesson of the elephant is that we cannot trust our impressions of what we have not truly seen. Midgley’s lesson is that if we want to get anywhere close to the truth, we simply cannot afford to leap to a conclusion that is half-baked.