Representational measurement of temperature

As indicated in the previous post, I plan to use the measurement of temperature to illustrate some ideas about perception.  This post will give a representationalist account of measurement, as an illustration of indirect perception.

The apparatus to be used is very similar to a mercury thermometer.  I shall assume that the reader is reasonably familiar with traditional analog thermometers, and how they are used.

The design of the instrument

The thermometer uses a glass tube.  At the bottom of the tube, there is a largish bulb which can be filled with mercury.  Above the bulb, the glass tube contains only a very narrow tube of small diameter, sometimes called a capillary.

The bulb is initially filled with mercury, and the mercury extends to part way up the capillary tube.  Above the mercury, the tube is empty.  The air is pumped out, though it need not be a perfect vacuum.

Contrasting direct and representationalist (indirect) perception

In a discussion at another site, I am noticing some misunderstanding of what is meant by direct perception.  I’m seeing comments similar to “vision uses photons, so is indirect.”  Those who favor direct perception have never denied that vision uses photons, retinal receptors and neurons.  The usually prefer saying that visual perception is mediated by photons, neurons, etc.  What they disagree with, is the idea that first a representation is formed inside the head, and then we perceive that representation.

Apparently this distinction is confusing.  So I plan a short series of posts where I contrast direct perception and representationalist perception.  This post is the introduction to that series.  The subsequent posts in this series are:

• Representational measurement of temperature
• Direct measurement of temperature
• Direct vs. representational perception — the discussion

Illustrating with science

It is sometimes said that scientific discovery is learning written big, and scientific data acquisition is perception written big.  The problems that science must solve to acquire useful data are similar to the problems that a perceptual system must solve to gather information about the world.  I shall use that analogy between perception and science, to illustrate what is meant by direct perception.

My next post in this series will give a representationalist account of getting temperature data.  I’ll follow that with a post on a direct way of getting temperature data.  And then, in one more post, I will attempt to point out the important distinctions.