oral part of a qualifying test

The oral part of a qualifying test is an especially grilling process to
graduate students because they have to think on their feet. However
clever you are, it is not always easy to come up an answer quickly,
clearly, and persuasively, when the professors are staring at you
and tapping their fingers impatiently.
The process could be traumatic to students with less self-confidence.
To prepare students for the test, I usually give them two advices.
One is to practice on explaining a difficult concept to their 70
years old grandma, and the other is 'It is all right to say you
don't know.'
Many people can memorize and cite definitions, equations, and facts
without any difficulty. But when you ask them what does that mean
exactly, they could offer nothing but to recite the definitions
again. The 'acid test' to see if someone really understands an issue
is to ask him to explain the concept to a layperson such as the
grandma. It is only when we really understand an issue that we can
explain it in plain and understandable language.
Many students stumbled on the simple quest. They threw jargons,
complex equations everywhere to disguise their lack of deep
understanding on the subject matter. They forgot the professors can
easily see through all these tricks.
But human nature dislikes failure and 'do nothing'. We feel so
shameful to acknowledge that we don't know the answer. So even
though every student was given the two advices before the test,
during the test, when the student found that he was in big trouble,
he always struggled to salvage his answer by throwing out more
smoke bombs based on some lame reasoning. The tension would then
be building up in the room, everyone was getting uncomfortable,
until finally the student burst out, 'I think I don't know the
answer.' The professors would usually respond, 'Finally! It's
about time. Now, let's see how do you think you can find out
the answer.'
Like many things in the life, timing is everything. It is very
important to acknowledge one's limitations at a right time.
Admitting one's ignorance too early shows that one is not taking
his job seriously, but doing this too late or totally denying
one's own ignorance is even worse because it shows that either
one is a liar or a fool. Ignorance is unfortunate, but unaware
of one's ignorance can endanger oneself as well as others.
Most of the people cannot do this properly. They feel compelled
to show others that they know everything, even though the cold
reality says that nobody can know everything. In one speech,
Richard Feynman talked about the importance of acknowledging
one's own ignorance. He said, it is the "not knowing" that makes
science progress. If we just think that we have known everything,
not only that is not true, but more importantly, it will only
drag our quest to uncover the truth.
That being said, it is very difficult to admit that there is
something you don't know. The student would rather juggle 10
things in the air while riding on a monocycle than to admit their
shortcoming. Everywhere we see examples like this. Not single
politician will admit that there is something he just doesn't
know. So we see politicians offer and insist their 'expertise'
on every issue. They have a solution for every problem. And
even stranger is that many people believe whatever they heard
from the so-called 'expert' opinion of the politicians. Feynman
said an honest and self-conscious candidate, when asked about
some issues unknown to him, should reply, for example, "I don't
know how to solve the problem about our ailing agriculture. But
if I were elected, I would summon all the top experts in this
area and have them come up a best solution to the problem."
It is very unfortunate that none of our politicians are capable
of these two simple things - to explain truth in understandable
and unbiased way, and to say 'I don't know' when necessary. But
even more unfortunate is that we let them get away with that. We
listen to their biased and overly simplified version of so-called
'truth', and we swallow every solution they throw to us. By not
challenging them, we are in fact encouraging them to become a bunch
of liars, reductionists, morons, or three-in-one.
Everything in this world is complex. Nothing is ever as simple as
any of the politicians might claim. We all prefer a simple solution.
50 brands of cereals only confuse us instead of making us happier,
and that's why politicians are feeding us with simple solutions.
But this desire for simple solution is precisely the reason that
Hitler killed millions of Jews, Pol Pot killed millions of
Cambodians, Serbs and Croats got to each other's throat, and
brothers turned against each other. Many politicians also found
out that the easiest way to elicit support for their simple
solutions was to paint the face of evil for their constituencies.
Serving as a motivator, hatred is as good as love. For some people
it is also much more comfortable to hate others than admitting
one's own fault and insufficiency.
So Jews is the face of evil to most Germans during WWII, as are
the Cham, Chinese, Khmer in Cambodian under Pol Pot regime, Serbs
and Croats to each other, and the South during the US civil war.
Our politicians are doing the same thing. Everyday, they preach
to us about what the face of evil looks like. That is a face of a
particular group of people who looked differently from us, behave
differently, talk differently, think differently, or who once
were or have been involuntarily put in a situation they cannot
really be responsible for. Relentlessly, we are taught to hate.
We are taught to identify the face of evil, and to hate people
with this face. How sad is this. When we should have hated the
foolishness, injustice, and prejudice, we chose to hate people.
But don't forget the table may turn. One day we might find us
on the other side, and people hate us and want to kill us for
no reason other than that their leaders tell them it is the
simple solution to a simple problem. Nothing involving more than
one person in this world could be that simple. Beware of the
self-proclaimed prophet who preaches you about a simple solution.
So when the test comes, be prepared. Ask yourself if you really
understand what is the issue at stake, and listen to the small
voice of your inner self when it says "maybe I just don't know."
Saying 'I don't know' is not a passive relinguish of our
obligation or right. It is an honest acknowlegement of our limitations.
Only by understanding our limitations can we move forward and
try to find another way out the chaos.