The Constraint of Custom:

I have written a lot about the problem of induction before. This was explained very well by the great Scottish philosopher, David Hume. Hume looked at the basis of beliefs that we hold such as:

  1. The sun will rise tomorrow; or
  2. If I drop this ball, it will fall to the ground

Hume noted that there is no uniformity in nature. In other words, it is not rational to believe that what has happened in the past will happen again in the future. Just because, we have seen the sun rise every single day of our lives, it does not guarantee that it will rise again tomorrow. We are using our experience of the sun rising to believe that it will rise again tomorrow. Even though, this might be irrational, Hume does not deny that we may see the belief of the sun rising as a sensible proposition. He notes:

None but a fool or madman will ever pretend to dispute the authority of experience, or to reject that great guide of human life.

It’s just that we cannot use logic to back this proposition up. We cannot conclude that the future is going to resemble the past, no matter how many examples of the past we have. We cannot simply use experience of the past because the only experience we have is of the past, and not of the future. Hume noted that to propose that the next future event will resemble the past because our most recent “future event” (the last experience event) resembled the past is circular:

All our experimental conclusions proceed upon the supposition that the future will be conformable to the past. To endeavor, therefore, the proof of this last supposition by probable arguments, or arguments regarding existence, must be evidently going in a circle, and taking that for granted, which is the very point in question.

Hume concluded that we fall prey to the problem of induction because we are creatures of habits:

For wherever the repetition of any act or operation produces a propensity to renew the same act or operation, without being impelled by any reasoning or process of the understanding, we always say, that this propensity is the effect of Custom. By employing this word, we pretend not to have given the ultimate reason of such a propensity. We only point out a principle of human nature, which is universally acknowledged, and which is well known by its effects.

In other words, it is our human nature to identify and seek patterns, use them to make predictions of the future. This is just how we are wired. We do this unconsciously. Our brains are prediction engines. We cannot help but do this. I will go further with this idea by utilizing a brilliant example from the wonderful American philosopher Charles Sanders Peirce. Peirce in 1868 wrote about an experiment to reveal the blind spot in the retina:

Does the reader know of the blind spot on the retina? Take a number of this journal, turn over the cover so as to expose the white paper, lay it sideways upon the table before which you must sit, and put two cents upon it, one near the left-hand edge, and the other to the right. Put your left hand over your left eye, and with the right eye look steadily at the left-hand cent. Then, with your right hand, move the right-hand cent (which is now plainly seen) towards the left hand. When it comes to a place near the middle of the page it will disappear—you cannot see it without turning your eye. Bring it nearer to the other cent, or carry it further away, and it will reappear; but at that particular spot it cannot be seen. Thus, it appears that there is a blind spot nearly in the middle of the retina; and this is confirmed by anatomy. It follows that the space we immediately see (when one eye is closed) is not, as we had imagined, a continuous oval, but is a ring, the filling up of which must be the work of the intellect. What more striking example could be desired of the impossibility of distinguishing intellectual results from intuitional data, by mere contemplation?

I highly encourage the reader to check this out, if they have not heard of this experiment. In fact, I welcome the reader to draw a line and then place the coin on the line. Doing so, the reader will see that the coin vanishes, however the line still remains visible in the periphery. This means that even though, our eye “sees” a ring, the brain actually fills it out and makes us see a “whole” picture. To add to this wonderful capability of our interpretative framework, the image that falls on our retina is actually upside-down. Yet, our brain makes it the “right-side” up. This would mean that newborn babies may actually see the world upside down and with voids, but at some point, the interpretative framework changes to correct it so that we see the world “correctly”.

How does our brain know to do this? The answer to this is that it was evolutionarily beneficial for our ancestors to do this, just like our custom to look for patterns. This is what Lila Gatlin would refer to as a D1 constraint. This is a context-free constraint that was evolutionarily passed down from generation to generation. This is a constraint that acts in any situation. In other words, to quote Alicia Juarrero, it is context free.

To go past this constraint, we have to use second order thinking. In other words, we have to think about thinking; we have to learn about learning; we have to look at understanding understanding. I welcome the reader to look at the posts I have written on this matter. I will finish with two quotes to further meditate on this:

Only when you realize you are blind, can you see. (Paraphrasing Heinz von Foerster)

The quieter you become, the more you can hear. – Ram Dass

Please maintain social distance, wear masks and take vaccination, if able. Stay safe and always keep on learning…

In case you missed it, my last post was The Cybernetics of “Here & Now” and “There & Then”

Process Validation and the Problem of Induction:

EPSON MFP image

From “The Simpsons”

Marge: I smell beer. Did you go to Moe’s?

Homer: Every time I have beer on my breath, you assume I’ve been drinking.[1]

In today’s post, I will be looking at process validation and the problem of induction.  I have looked at process validation through another philosophical angle by using the lesson of the Ship of Theseus [4] in an earlier post.

US FDA defines process validation [2] as;

“The collection and evaluation of data, from the process design stage through commercial production, which establishes scientific evidence that a process is capable of consistently delivering quality product.”

My emphases on FDA’s definition are the two words – “capability” and “consistency”. One of the misconceptions about process validation is that once the process is validated, then it achieves almost an immaculate status. One of the horror stories I have heard from my friends in the Medical Devices field is that the manufacturer stopped inspecting the product since the process was validated. The problem with validation is the problem of induction. Induction is a process in philosophy – a means to obtain knowledge by looking for patterns from observations and coming to a conclusion. For example, the swans that I have seen so far are white, thus I conclude that ALL swans are white. This is a famous example to show the problem of induction because black swans do exist. However, the data I collected showed that all of the swans in my sample were white. My process of collection and evaluation of the data appears capable and the output consistent.

The misconception that the manufacturer had in the example above was the assumption that the process is going to remain the same and thus the output also will remain the same. This is the assumption that the future and present are going to resemble the past. This type of thinking is termed the assumption of “uniformity of nature” in philosophy. This problem of induction was first thoroughly questioned and looked at by the great Scottish philosopher David Hume (1711-1776). He was an empiricist who believed that knowledge should be based on one’s sense based experience.

One way of looking at process validation is to view the validation as a means to develop a process where it is optimized such that it can withstand the variations of the inputs. Validation is strictly based on the inputs at the time of validation. The 6 inputs – man, machine, method, materials, inspection process and the environment, all can suffer variation as time goes on. These variations reveal the problem of induction – the results are not going to stay the same. There is no uniformity of nature. The uniformities observed in the past are not going to hold for the present and future as well.

In general, when we are doing induction, we should try to meet five conditions;

  1. Use a large sample size that is statistically valid
  2. Make observations under different and extreme circumstances
  3. Ensure that none of the observations/data points contradict
  4. Try to make predictions based on your model
  5. Look for ways and test your model to fail

The use of statistics is considered as a must for process validation. The use of a statistically valid sample size ensures that we make meaningful inferences from the data. The use of different and extreme circumstances is the gist of operational qualification or OQ. OQ is the second qualification phase of process validation. Above all, we should understand how the model works. This helps us to predict how the process works and thus any contradicting data point must be evaluated. This helps us to listen to the process when it is talking. We should keep looking for ways to see where it fails in order to understand the boundary conditions. Ultimately, the more you try to make your model to fail, the better and more refined it becomes.

The FDA’s guidance on process validation [2] and the GHTF (Global Harmonized Task Force) [3] guidance on process validation both try to address the problem of induction through “Continued Process Verification” and “Maintaining a State of Validation”. We should continue monitoring the process to ensure that it remains in a state of validation. Anytime any of the inputs are changed, or if the outputs show a trend of decline, we should evaluate the possibility of revalidation as a remedy for the problem of induction. This brings into mind the quote “Trust but verify”. It is said that Ronald Reagan got this quote from Suzanne Massie, a Russian writer. The original quote is “Doveryai, no proveryai”.

I will finish off with a story from the great Indian epic Mahabharata, which points to the lack of uniformity in nature.

Once a beggar asked for some help from Yudhishthir, the eldest of the Pandavas. Yudhishthir told him to come on the next day. The beggar went away. At the time of this conversation, Yudhishthir’s younger brother Bhima was present. He took one big drum and started walking towards the city, beating the drum furiously. Yudhishthir was surprised.

He asked the reason for this. Bhima told him:
“I want to declare that our revered Yudhishthir has won the battle against time (Kaala). You told that beggar to come the next day. How do you know that you will be there tomorrow? How do you know that beggar would still be alive tomorrow? Even if you both are alive, you might not be in a position to give anything. Or, the beggar might not even need anything tomorrow. How did you know that you both can even meet tomorrow? You are the first person in this world who has won the time. I want to tell the people of Indraprastha about this.”

Yudhishthir got the message behind this talk and called that beggar right away to give the necessary help.

Always keep on learning…

In case you missed it, my last post was If a Lion Could Talk:

[1] The Simpsons – Season 27; Episode 575; Every Man’s Dream

[2] https://www.fda.gov/downloads/drugs/guidances/ucm070336.pdf

[3] https://www.fda.gov/OHRMS/DOCKETS/98fr/04d-0001-bkg0001-10-sg3_n99-10_edition2.pdf

[4] https://harishsnotebook.wordpress.com/2015/03/08/ship-of-theseus-and-process-validation/

[5] Non-uniformity of Nature Clock drawing by Annie Jose