-Shivprajval Divakar

We can now say that we have carried out (in however rudimentary a form) an experiment. At this point, it may prove fruitful to keep in mind what we did while carrying out the experiment and ask why we did it. The most obvious question first- Why do we carry out experiments? One answer that could be given is that we wanted to verify a claim. In this case, the claim would be that the stem transports water and minerals in an upward direction to different parts of the plant. From this perspective, an experiment is a process we adopt so as to verify a claim. We can recollect the process we carried out (or read it by clicking here) and compare it with the process stipulated in the textbook.

The textbook required us to carry out the following process-
“We would require a glass, water, red/blue ink and a soft stem. Pour water to fill one-third of the glass. Add a few drops of red/blue ink to the water. Cut the base of the stem and put it in the glass as shown in Fig.7.6.”
Figure 7.6 from the textbook is shared below-

But the process we employed differed in some ways-

1. Except in the case of plant B, all plants were dipped in containers filled more than half their volumes with ink-water, as opposed to filling them only one-thirds as stipulated by the textbook.

2. None of the containers were in the shape of the glass depicted in fig 7.6 above.

3. The material out of which the containers were made was plastic in some cases, whereas we were required to use glass.

4. I did not buy a dropper to add ink and hence just poured some ink into the containers, while we were asked to add a few drops.

Hence, it appears prudent to do the experiment again, only this time, we carry it out more in alignment with what the textbook recommended. But of course, there is the possibility that the process the textbook recommended may not be the best process to test the claim identified. We will discuss this in more detail later.

I had offered the attempt to verify claims as a reason for conducting experiments. I would like to give one more reason now. Experiments also have an element of playfulness and curiosity to them. Many a times, there is no reason behind why they are conducted apart from just wanting to see what would happen if they were conducted. In the spirit of this playful exploration, I will make the following modifications to the original setup and initiate a new series of experiments. Instead of water and ink, I will dip the stem in-

1.starch solution

2. sugar solution

3. salt solution

4. iodine solution

5. solutions of colouring agents for food

6. alcohol

7. coca-cola.

I would like to share yet another reason to conduct experiments. Experiments are the final test of a scientific theory, we often hear. Experiments are the final stamp of approval from the scientific community to legitimize scientific knowledge. Therefore, we can look at experiments as a process by which scientific truths are manufactured. My strongest reason for conducting this experiment (and future ones) is to understand this process by carrying it out first-hand, reflecting on that experience, incorporating those reflections in future experiments, reflecting on those further experiments, and so on in a cyclical manner. I hope that with every iteration, I will improve upon my knowledge of the process by which scientific truths are arrived at.

With this in mind, let us continue with our reflection over the experiment. After setting up the experiment, we were asked to make a few observations. These observations were crucial in deciding the outcome of the experiment (whether the claim is true or false). We can ask why this is so. What is so special about observations that we give them this central role in the scientific practice? To answer this question, it may be prudent to consider some of the sources of our knowledge and comment on their nature.

Consider the following questions-

1.Have the leaves of the plant turned red?

2. Is your stomach aching?

3. What is the product of the numbers 667725 and 98332?

4. Are you upset with me?

5. What did you eat yesterday?

To answer the first question, we use our eyes. Therefore, our eyes are a source of knowledge. Similarly our ears, nose, skin, and tongue also serve as sources of knowledge. Let us call the knowledge we acquire through these sense organs ‘perceptual knowledge’. Observations rely on perceptual knowledge. To answer the second question, we rely on our bodily sensations, perhaps through the action of nervous tissue. This is not the same as perceptual knowledge because it does not rely on the sense organs, the skin included. Let us call such knowledge ‘knowledge through bodily sensations’. To answer the third question we use the mind and reasoning. Let us call this ‘conceptual knowledge’. To answer the fourth question we notice our emotional state. Let us call this ‘emotional knowledge’. To answer the final question, we rely on memory. Let us call this ‘knowledge through memory’. These are all some means for us to ‘know’.

Let us make a comparison of the different ways of knowing listed above. A useful question we could ask is that of where in space these different means of knowing can be accessed. To access perceptual knowledge, we need to ensure our sense organs receive inputs from a source which is outside the body. If we were to shut our eyes, we would not see. If we were to shut our ears, we would not hear (we may need to stuff something in it or cover it with something for louder sounds). What we do not touch, we cannot feel through the skin. Also, the closer we are to the source, the greater our ability to perceive it in all its details.

On the other hand, we cannot walk away from a stomach-ache like we can from loud music. We cannot move closer to or farther away from it. We also cannot just ‘switch off’ the stomach ache at will, unlike perceptual knowledge. Similarly, we carry our emotions, reasoning, and memories wherever we go. We cannot move closer or farther away from them either. Nor can we switch them off.

Based on these basic distinctions between perceptual knowledge and other forms of knowledge, we can argue that the latter forms pertain to knowledge of the ‘self/subject’, while perceptual knowledge pertains to knowledge of the ‘other/object’. Perceptual knowledge is knowledge of objects belonging to a shared reality inhabited by multiple subjects. Therefore, if I were to make a few observations related to the coconut tree in my house, another person can verify them by visiting where I live and making those observations first-hand. The other person will not need to take my word for it. Therefore, making the results of experiments contingent on perceptual knowledge ensures that the scientific knowledge constructed has an element of ‘objectivity’ to it.

But what can we say of how scientific knowledge disregards some of our perceptual knowledge, branding them to be mere ‘illusions’? The popular example given for an illusion is that of seeing water while driving on a road in the hot sun. Another example is that of how a stick appears to be bent when submerged in water. I would also like to present as an example of an illusion the process of reflection.

What is common to these instances of illusion? I would argue that they all are instances wherein we receive contradictory inputs from our sources of knowledge. While from a distance it appears that there is water on the road, as we approach closer to it, it vanishes! This runs contrary to how we described the nature of perceptual knowledge to be such that when we approach closer to an object being perceived, we can perceive it better (with finer details). Therefore, we become aware of a contradiction between our memory of how perceptual knowledge operated before, and how it is operating now.

Similarly, while the stick is seen to be bent in the water, once we run our fingers along it, we cannot feel a bend in the stick! This is an instance of contradictory inputs between two perceptual sources of knowledge- sight and touch. Likewise in the case of reflection. While we can see the image of a tree in a puddle of water, once we jump into it, we can feel no tree! I would argue that it is such contradictions that alert us that we may be experiencing an illusion. Since we have come across no such contradiction so far in the experiments we conducted, I am inclined to give perceptual knowledge its crucial status in the outcome of these experiments.

We have discussed at some length why we made observations as part of the experiment. What did we do after making observations? We took photographs which depict what was to be observed. Why did we do that? To answer this question, we need to look into the idea of ‘evidence’ in science. While an observation allows us to confirm for ourselves the outcome of an experiment, how do we convince others of the same? Like I said earlier, if I were to make observations about a coconut tree in my house, another person can verify it by visiting where I live. But if I were to take a photograph and send it to the other person, she would be able to verify it for herself without needing to travel to my home. Similarly, I can share the call of a bird by taking a recording and sending it to other people. But to share other aspects of my perceptual knowledge may not prove as easy.

What did we do next? We were asked the following question-

“Does the colour appear in the stem?”
We then looked at our evidence and answered the question. This is another advantage of collecting evidence instead of just making observations. We can consult the evidence even when we are not able to directly perceive the object or its properties, and also when we cannot recollect the observation we made.
But, how did we answer the question? We can recollect the discussion we had related to the question- what is a plant? It can be read by clicking here. There, we had discussed how the word ‘plant’ can be understood in terms of other words (the definition of the plant) and also by observing many of the things we call plants. But we also recognized that there is an element of ‘vagueness’ about it. We had appreciated the role of language in communication in spite of this vagueness.

Here also, we use language to understand what the question means, compare that meaning with our evidence, and comment on their relationship. Even in our earlier discussion related to some of the sources of our knowledge, we used language to answer every question we posed. So, we could ask- what is the source of our knowledge of language? For now, I would like to bring up the question without giving a straightforward answer. I am sure that it will come up in other contexts. So we could postpone the discussion to then. But for now, we can agree that language plays a crucial role in the construction of scientific knowledge, perhaps just as much as observation.

We then encountered two predictions that the textbook made-

“You will find that the colour rises in the stem.”

“If this is kept for a longer period, the colour appears in the veins of leaves also.”


Comparing these predictions with our evidence (using language as before), we responded saying that in some cases, the predictions were in alignment with our evidence, and in some cases, they were not. This could be termed the result of the experiment.

But why do we make predictions? Predictions serve as a means of accountability on the part of the people proposing scientific knowledge. This ensures that they stipulate conditions under which they will consider their claim to be proven false or the process for verifying the claim to be false. This applies to the textbook too. So, was the claim wrong or was there a flaw in the experiment? If it is the claim that is false, we have disproved a very foundational belief in biology. If the experiment we conducted was faulty, we need to consider in what ways we have digressed from the way the textbook stipulated the experiment and bring our experiment in alignment with it (which we were planning to do anyway), and in what ways the textbook stipulated experiment itself could be faulty.

To assess whether the experiment proposed by the textbook is a good one, I will need to consult the currently held view related to transportation of water and minerals in plants. Once I read up on the matter enough, I will try to critique the experiment design, and also attempt to create a better version of the experiment.

This article is part of a series attempting a philosophical analysis of biology as encountered in NCERT textbooks. To read the concept note for the series, click on the link below-https://www.barefootphilosophers.com/concept-note-for-series/


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