Bill's five easy pieces

[From Fred Nickols (970930.0615 ET)]

Bill Powers (970928.1100 MDT)]

PCT deals with only one phenomenon of behavior: control. However, not
everything that is called control is dealt with by PCT. the reason is that
control is given many meanings in ordinary language, and only some of these
meanings relate to the phenomenon that PCT explains. The word "control" is
a technical term in PCT, just as the word "work" is a technical term in

The definition of control that is used in PCT is as follows:

A is said to control B if A can act on B to change its state, and if for
every change in B, A changes in such a way as to restore B to a value near
some reference value B'.

You are invited to answer the following five questions using the PCT
definition of control.

1. The rate of a chemical reaction doubles for every 10 degrees c of rise
in temperature. Does temperature control the rate of a chemical reaction?

Temperature (A) is said to "cause" a doubling in the rate of chemical
reaction (B0. However, there is no reference condition (B') given, and no
indication that temperature changes to maintain it. I'd answer this one "No."

2. On a radio there is a knob fastened to the shaft of a potentiometer. A
clockwise rotation of the knob causes the sound volume from the radio to
increase. Does the knob control the volume?

Turning the knob (A) leads to increased volume (B). As in the first
question, no reference condition (B') is given nor is there any suggestion
that the knob is adjusted to maintain it (although it certainly could be).
Again, my answer is no. (In this case, I think the listener sets B' and
uses the knob to make B align with it. My teen-agers, by the way, had a
very different B' than did I.)

3. A dog is trained so that when a bell is sounded, the dog salivates. Does
the sound of the bell control the dog's salivation?

The bell (A) seems to trigger salivation (B). Again, no B' is specified nor
is any adjustment of bell-ringing to maintain it indicated. Again, I answer

4. The accelerator pedal of a car, when pressed down, allows more gas-air
mixture to enter the engine, thus making the engine deliver more power or
torque output. Does pressing the accelerator control the power or torque
output of the engine?

Same as above. No B' is specified and no adjustments to A to keep B aligned
with B'... Answer = No.

5. A computer senses the position of a target and computes the aiming angle
and firing time of a gun so when the shell crosses the path of the target
it will hit the target. Does the computer control the path of the shell?

Nope. At best, the computer controls the position of the gun barrel at the
time of firing (or, as I think Rick would prefer, the gun mount controls its
own position in relation to a reference condition (gun order) calculated by
the computer). Once the projectile leaves the gun barrel, its path is a
matter of ballistics; factors like air density, the shape of the projectile,
the force imparted by the propelling charge, and even good old gravity take
over. The projectiles are literally thrown at the target. Moreover, if my
memory serves, the computer doesn't calculate a path for the projectile to
follow but, instead, uses known paths that projectiles follow to calculate a
position for the gun mount to assume.

If I have stated these question and the condition clearly, there will be
only one possible answer to each question. Let me know what answers you get.

In all cases, my answers are "no" and, in all cases, because there is no B'
specified and no evidence of changes in A that keep B aligned with B'.

P.S. Do I get any credit for showing my work?

Fred Nickols
Senior Consultant
The Distance Consulting Company