Well, today we will talk about one of the central doctrines in science: Causality.
Causality is almost at the basis of all science. Because whenever something happens, we believe
that there must have been a cause and we try to find the cause, and much of science is
builtby doing so: looking for the cause of something that has happened.
So, causality is one of the central doctrines in science.
But even though it is such a centralissue in science,for much of human history it was
not clear how to define the cause of an event. And so, it has been subject of great controversy
how to identify the cause of an event what do I call a cause
But, through the millennia of attempts, presently we have obtained some clarity and we do understandwhat
can be seen as the cause of an event and that is what we will talk about.
But, we will I will take you through the course of human history through which this idea developed.
It is not difficult to see that some rudimentary idea of causality must have been there for
any human action to take place. And for that matter, even the ancient people,
even at the dawn of human civilization, then also people must have some rudimentary idea
of causality. Tigers cause death and therefore stay away
from tigers. The seed of today cause the tree of tomorrow.
And so, place that seed where you want the tree of tomorrow.
That is the start of agriculture. And it is not difficult to see that some rudimentary
concept of causality must be there in order for thisthese things to develop.
For even a normal day-to-day life of an ancient living in the hunting gathering society, then
also some rudimentary idea of causality, what is causing what, one must have obtained that.
Otherwise it is practically impossible to even lead a day-to-day life.
But, these are intuitivenon-refined ideas of causality.
We see the first refined and articulated idea of causality in the Greek period.
Again, in the writings of Aristotle. Aristotle saw that whenever we are trying
to figure out the cause of any event, we can look for the cause from four different angles.
Um four different angles. Now, he specifically gave an exampleto illustrate
what these four different angles are. And I will cite the same example.
So, let us start our discussion of causality with Aristotle.
"Aristotle's causality" He said, suppose there is a marble statue
and you are trying to find the cause of the marble statue.
How would you look for the cause? You might say that the statue is made of marble
and therefore, the marble must be the cause. Because if the marble were not there, that
particular kind of white stone—if that were not there, then the statue would not be there.
So, that the material with which the thing is built is a cause and he said it is a 'material
cause'. So, what is the material cause?
If you are looking for the cause of anything, there is some material with which it is done,
and if that material were not there the thing would not be possible and so, that material
is a cause. In case of the sculpture, the white stone,
marble, is a cause. That is the material cause.
Then he said that this sculptor, the artist who made the sculpture, must have a have the
idea of the form of that sculpture in mind before he started to work on the stone.
Only if one has a idea of what he is going to make, then only one can start working on
the stone. So, the form of the sculpture must be there
in the sculptor's mind in order for him or her to make the sculpture, and that Aristotle
said, is the 'formal' cause. "Formal cause".
And then he said the... of course, the sculptor himself—the artist himself is a cause because
if the artist himself or herself were not there, then the sculpture would not be built.
So, the agent, in case of in general situation, the agent which actually does it; the agent
which actually makes it happen, that is of course a cause and he called it the 'efficient'
cause. So, the difference between the formal cause
and the efficient cause, according to Aristotle, was that the efficient cause is the is the
is the person or the agent which has done it, these artists in this case, but the formal
cause is the the the artists had the idea of the form of thesculpture in mind before
he started working on the stone. And so, that form of the final thing is what
is the formal cause. And then he said that there must be some purpose
for which this sculpture is built. Some end result, the objective to fulfill
which this sculpture has been made, and that he said is the 'final' cause.
And in general,if you are looking for the cause of something, you have to you have tofigure
out the 'what is the ultimate objective of that to happen or a thing to be build'.
'Ultimate objective'—what purpose does it serve?.
So, that is the final cause. And Aristotle said that... He gave you this
particular example, but he said that in general, whatever cause you look for, whatever events
you investigate, you look for the cause; you look for that from these four different angles
and you will find four different types of causes.
So, that was Aristotle's idea of causality. Following Aristotle's time,you see Greek period
was followed by the Roman period. And the Roman period was followed by what
is known as the dark age, medieval period in Europe.
Andin between Christianity developed. And during the medieval period that became
the dominant form of thinking. And during that period, Aristotle's ideas
actually were accepted and accepted into the church dogma.
And in that period, the final cause became the most important.
Because whatever happens, people wanted to see the hand of God in everything that happens.
And that was seen as the final cause. So, the final cause became all important during
the medieval period. After the medieval period came the renaissance.
And during which we have giantsin various fields of human endeavor.
We have Copernicus, Bruno, Galileo in field of science.
We have Leonardo da Vinci, Raphael, Michelangelo and a large number of artists, literatures.
So,cultures sprouted in all directions. The scientists of the time, obviously, had
to worry about causality. Because they were investigating natural phenomena
without the baggage of the belief systems of the earlier period and so, naturally he
had they had to worry about the cause of various things.
But we do notsee a a full treatise on causality in the writings of the renaissance scholars.
Only in Galileo's writings we find a rejection of the final cause.
He said that there is I do not believe in this there is to be any final cause.
And he only rooted on the material cause and the the the these three, the other three.
But he was pointing out that the formal cause, the form of the or the idea that the sculptor
had is a part of the the person. So, this is actually can be subsumed in the
efficient cause. So, he was actually saying that when you look
for causes look for the material cause and the efficient cause.
What, with what is it made and who made it. But beyond that, we do not see much treatise
on causality in the Renaissance scholars' writings.
Following renaissance, there was a period which is called the 'period of enlightenment'.
During that period,we see the firstreasonably goodtreatise on the problem of causality—philosophical
treatise on the problem of causality from aa British philosopher called David Hume.
Hume wrote a bookcalled 'A Treatise on Human Nature' in which there was a reasonably good
exposition on the problem of causality. His attempt wasto develop some way of defining
causality which can be tested. And he said that if I say A is the cause of
B, then the following conditions must be satisfied. First,'precedence': A must precede B.
, So. So, in order for A to be called the cause
of the effect B, A must precede B. Second, he said 'contiguity', which means
A and B must not be widely separated in space and time.
So, let me write: "A and B not separated in space and time", that is there, they have
to be contiguous. For example, if a murder has been committed
the police would look for the the murdererin the immediate neighborhood of the place
So, it is like that. It follows from common sense you can say.
Andthird his point was, if A is to be called a cause of B, then another condition has to
be satisfied, that is called constant conjunction. "Constant conjunction".
Constant conjunction meansA and B always occur together; that means, whenever A happens B
must happen. Or whenever B happens, before that A must
have happened. So, whenever such constant conjunction is
observe observed we can say that A is the cause of B
And he said that, if these three conditions are satisfied, then I can call A to be the
cause of B. through this, notice that all these three
conditions are testable. Whether A is preceding B or not testable.
Whether A and B happened more or less at the same place or notthis is testable.
And constant conjunction: whenever A happens B happens or not that can be testable.
So, he developed testable criteria to define causality.
And that was a big step, because now things were moving in the direction of testability,
moving in the direction of materialism. So,his step was in that direction.
However, soon it wasnoticed that his criteria of defining causality had some important flaws,
crucial flaws. For example,let us take the issue of precedence.
One German philosopher Immanuel Kant, in his book pointed out the problem of this precedence
requirement is that, he said that suppose there is a sofa andyou place a heavy iron
ball on it; it will make a dent. What cause the dent?
Obviously, the pressure of the ball. But the pressure or the ball resting on the
sofa and the dent appearing happened at the same time.
It is not that you first place the ball and then after some time the dent appears.
And therefore, Kant made the point that, you cannot say that A must precede B.
Rather you should say that B cannot precede A.
The effect cannot precede the cause. Let us come to the second issue, contiguity:
the cause and the effect should be contiguous. They should not be widely separated in a space
and time. But, take the event of the tide.
The tide is called caused by the attraction of the moon.
And therefore, the cause, which is the moon, is quite distant from where the effect happens,
and they are not contiguous. The third, constant conjunction.
Suppose you want to check whether the mosquito bites cause malaria.
Let us take this case. Do mosquito bites cause malaria?
Now,if mosquitoes containing the parasite bite a 100 people, maybe 90 will be afflicted
by malaria, but 10 will not, because of their ownbody-resistance.
And therefore, the constant conjunction, 'whenever A happens B happens' will be violated.
Cannot we then say thatmosquito bites cause malaria.
According to Hume, since constant conjunction requirement is violated, you cannot say.
But then we realize that that criterion is faulty.
We have to do something else in order to work out the causality.
So, that was the situation,after David Hume. Another point was, Hume said thatcausality
actually is our mental construct. We see things happening in succession, one
after the other. We see cloud and then the rain, and so our
mind forms a a link between them. And our mindestablished establishes a causal
connection. It is not really necessary that nature has
such a causal connection. It is our mindsfinding a pattern in the events
in nature. While Kant made the point that we see this
pattern in nature. B following A always happening and thenwe
we see a pattern in nature that is because there is a physical causal connection between
A and B. A is actually causing B.
It is not justarbitrary things happening in succession.
So, there is a... Kant's point was that there is a physical
way by which A is influencing and making B happen and that is why the causality is actually
a physical phenomenon. Something that happens in nature.
There is causality in nature and that is why we see a succession of certain things, one
after the other. That was Kant's point.
So, let me write the name: "Immanuel Kant". Sorry.
How do we look for causality? How do we plan experiments to find causality
in nature? AfterKant, in the middle of the 19th century,this
point was illuminated by John Stuart Mill. So, now we come to the work of "John Stuart
Mill", a famous philosopher of the 19th century. he proposed certaincriteria by which one can
design experiments and one can test causality. One canspecify what causes what.
If, in a specific situation, you are trying to find out what caused a specific things,
specific event thenJohn Stuart Mill gave the prescription as to how to look for the cause.
the 1st he said: "The method of concomitant variation".
What is it? He said that if there are two variables, A
and B, andwhenever A increases you see that always B either increases monotonously or
decreases, then you know that there is a causal connection between A and B.
So, whenever A is increasing, so, it is question of variation.
Concomitant, so, A is varying and B is varying concomitantly: either whenever A is in A increases
B also increases or whenever A increases B always decreases.
When that happens, then you would say that there is a causal connection between A and
B. You cannot say A causes B because it is possible
that the opposite is true: B causes A. But there is a causal connection, that you
can assert. So, that is the method of concomitant variation.
The 2nd, he said "the method of agreement". Imagine,two situations in which some event
B happens. So, the event B happens, and the situation
preceding to that are different. Okay?
let me write. "Event B happens",in many situations.
"Conditions leading to B are different". But one particular factor A is common to all
of them. So,the B the event B happens in various situations,
the situations differ, but there is a common factor between all these situations: the factor
A. In that case Mill says that you might call
A to be the cause of B. Okay?
So, method of agreement; that means, all the situations agree on one point, the existence
of the factor A. Then you might say A is causing B.
The 3rdthe method of difference. The method of difference is where the event
B happens in one case and does not happen in another case.
So, it happens and does not happen and the antecedent situation, the conditions prevailing
before the occurrence of the event B, are more or less the same in both cases, but they
differ in only one aspect. Okay?
So,in one case the event B happens and, in another case, it does not.
The conditions prevailing before thishappening and not happening are more or less the same.
They only differ in one aspect. "The condition differ in one aspect let us
call it A". Then so, in one case A was there and B happened,
another case A was not there and B did not happened.
But otherwise the conditions were same. In that case you might call A to be the cause
as B cause of B. So, that is the method of difference.
And 4th he said 'the method of residue'. There are situations wherethere can be various
factors existing in the condition receiving a particular event; various factors, say P,
Q, R, S. There are various factors that are existing
in the condition preceding an event B, which is happening.
Now, from prior research you know the what what is caused by P and that is not B.
You know what is caused by Q and that is not B.
You know what is what can be caused by S and that is not B.
But B actually happened. But, in the antecedent things there is something,
one thing, say R whose result you do not know, whose effect you do not know.
But, there is a residual condition existing prior to that event.
Residual, whose whose effect you do not know. But you find that something else happened,
B happened and B cannot be the result of P or Q or S.
Then you might say then the residual condition that was existing, R is the cause of B.
So, in this situation you have the event "B" happening and before that the situations prevailinghad
theaspect, say let us call it "P", another aspect let us call it "Q", another aspect
let us call it R, let us another aspect this is called "S".
All these were there in the condition prevailing before the occurrence of B.
So, B is the effect that we are trying to find out.
And from prior research you have clear idea as to what can be caused by P.
So, you know that B cannot be caused by P, you know B cannot be caused by Q, you know
B cannot be caused by S, because you know what can be caused by S, Q, P.
But you do not know the effect of R. This is the the residual part, whose effect
is yet unknown. And you know that B cannot be caused by P,
Q, S, but you do not know what is the what is the result of R.
And something else has happened which cannot be caused by P, Q and S.
So, R is the residue. Then you might say that R is the cause of
B. So, that is the point of the method of residue.