Re: Why: Why?

J.D. Guzman (
Mon, 13 Apr 1998 23:36:09 -0500

-----Original Message-----
From: Dario Giraldo <>
To: <>
Date: Monday, April 13, 1998 6:38 PM
Subject: Re: Why: Why?

>On Mon, 13 Apr 1998, Tom Pearson wrote:
>> snip...
>> post cited above is related to an assortment of logical errors that I
>> seen not only in Dario's comments, but in a fair amount of the
>> snip...
>> First, in dealing with scientific matters -- indeed, in dealing
>> anything we encounter in this life -- we are not dealing with certainties
>> all.
>Excuse me Tom, but for someone calling my comments ilogical to go and make
>such an assertion as your prior statement makes me wonder. Lets see, we
>have natural laws and what makes then laws is their unchanging nature.
>Let's take gravity. It is very certain that if I climb to the Space
>Needle and take a step beyond the terrace into the air I will fall to the

Dario, the laws of science are based on the evidence that has been aquired
through the years. The law of gravitational attraction is not a certainty,
it is based on the observation that, for quite a long time now, things don't
fly off the earth but are held to it by a force that we name gravity.
However, as Tom is arguing you cannot be certain that tommorow things will
continue the same. Could you beyond a shadow of a doubt say that the law of
gravity will continue working tommorrow as it does today. If you answer yes
to this question I suggest you pick up the either of these two books, The
Last Three Minutes or About Time, both of them by Paul Davies.

>> Certainties are normally reckoned to be derived from proofs. But
>> science doesn't traffic in proofs. It deals with evidence, and the
>> subsequent reasoning that seeks to integrate and account for the
>What is the difference between proof and evidence ?

There happens to be a big difference between proof and evidence. Let's
suppose that I am a lawyer and I am prosecuting person X for murder in the
first degree. In the course of my investigation I was able to find the gun,
that was used in murder. To my delight I found it in a dresser drawer at
person X's house. While in court I call the police officer that found the
gun at person X's house. Having called up the officer I proceed to ask him
a series of questions. Is this the gun that was used at the scene of the
crime? Whose finger prints were found on the gun? And the all important
question, where did you find this gun? The police officer answers all of
these questions in such a way that the poor defendant seems to have no hope;
however, I, not being in all my senses, decide to ask, Can we be positive
that this gun was fired by person X, which led to the death of person Y, and
therefore prove that person X is guilty? Of course the police answer has to
answer no. Why? Well because although the gun was found at his house with
his finger prints, this is only evidence that person X is guilty. Just
because the gun was found at his house with his finger prints doesn't prove
anything, it only gives us good reason to believe that person X did it.

This is the difference between proof and evidence.

>> But this produces no proof of anything. For instance, if you are driving
>> down the street, and a child runs out in front of your car, can you be
>> *certain* you will strike and injure the child? Of course not. You have
>> proof of anything here.
>If my car is a 4500 lbs vehicle, I'm traveling at 90mph, the child is
>less than 60 feet from the car and the brakes in the car are rated to have
>a stopping distance of 140 feet from 60mph to 0, you can be certain that
>the child will be injured. And this event can be reproduced in the lab
>one thosand times with the same results.

True this can be reproduced in the lab, only if the child is made inmobile.
In real life the child has the ability to move, you may be able to predict
the actions of the car at every second, but you can't predict what the child
will do. So we are back to what was said before, you only have evidence
that you will hit the child, but you can't be positive that you will.

>> Why, then, do you attempt to stop the car, or avoid the child?
>> Because you have good grounds for concluding that the evidence before
>> you indicates the appropriate response.
>Or because hope is the last thing you lose. As humans with some degree of
>conscience will always try to prevent injury to other one specially if is
>a child. But this isn't always the case as hit and run accidents do
>happen every day.
>> Again, if you have a severe
>> toothache, can you be certain that going to the dentist will not make the
>> problem worse? If you can't prove that, wny bother going? In short, if
>> waitied until we were always in possession of a priori certainty before
>> rendered a judgment, we would know nothing, and act on everything
>> indiscriminately.
>But there are things that we know for sure and certain of them such as the
>sunrise in the morning. Or since the 15th approaches, taxes will be paid
>by those who are under the w-2 system.

All of these things are temporal. Tommorow, however unlikely it may be, the
U.S. government might decide that there will be no more taxes. Or maybe at
the turn of the century all the IRS computers will fail and no one will be
charged taxes. Likewise we can't be sure that the sun will rise tommorow,
we can only deduce that given proir expirience and observation we have a
99.9% chance of seeing the sun rise tommorow.

>> Science does not proceed that way, and neither does life.
>> Asking for science to become "exact," in the sense of providing
>> "certainties," is a red herring, and does not deserve to be taken
>Really? When I climb on an airplane, have science been exact in the
>development of this device? Or we are never certain that this plane will
>fly? As someone who made a living in the aerospace industry and was a
>test flight technician I never doubted that my plane will fly. My concern
>was with other technicians work not the results of the scientific research
>which yielded the aircraft. That much was for certain.

The flight of the plane depends on the assumption that the conditions that
allow the plane to fly today will be the same to tommorow and the next.
This is only an assumption though, and we can't be positive that the laws
that allow a plane to fly today will allow it to fly tommorow, we can only
be somewhat confident.

Best Regards,

J.D. Guzman