The Stevenson Screen was invented by Thomas Stevenson (1818–1887).1 It is essentially a slatted box, within which there is a thermometer (usually among other measuring devices) that is used by professional meteorologists to measure the surface air temperature of the planet Earth. The nature of its construction allows the flow of air through it, but shelters the thermometer from direct sun, rain, wind, and radiated heat from its surroundings; it is set at a determinate height about the ground, thereby delivering a consistent standard air temperature reading.
The aim is to minimize contingent variations of placement so that the air temperature reading taken in one place is as far as possible truly the air temperature, and not a temperature determined or affected by any other features of where the screen happens to be. Without this it would not be safe and accurate to say that any two places were the same or different in temperature, for without the screen the similarity or difference might be a result of the effects of different local circumstances other than the air temperature.
Kant’s Categories are those features of our experience that are determined by our mode of apprehending the world, and they are invariant between the particularities of the content of those experiences. They apply to all experiences of the world, but do not arise from those experiences. But to have content, the Categories have to be applied to experiences, and for experiences to be anything we can understand, they must conform to being formed by or falling under some of the Categories.
As Kant put it:
‘Thoughts without content are empty, intuitions without concepts are blind’2.
In this way, Kant aimed to avoid both a position where metaphysical speculation falsely claims knowledge about the world independently of experience, and a pure empiricist position which hold that knowledge of the world may be derived only from experience, but which results in scepticism of fundamental ways we have of thinking about the world. The first of these positions was associated with Gottfried Leibniz and his followers, and the second with David Hume.3
Kant held that we could know certain things were true of the world independently of experience (a priori) but they only have meaning if those determining forms of thinking were applied to and combined with the content of experiences of the world (a posteriori). Only in that way …
Originally appeared on Daily Philosophy Read More