Having suggested that cognition is measurement, it is time to say a little about what measurement is.
The most common view seems to be that we passively receive data at sensory cells, and then use logic or computation as applied to that data. When data is received from a sensory cell, I shall call that sensing (for want of a better term). My aim will be to draw a distinction between measurement and sensing, though in ordinary language usage the two overlap somewhat.
With sensing, the sensor reports the immediate environmental conditions which trigger a reportable change in the state of the sensor. The sensor under the highway reports the effect of a passing vehicle, and that sensor data is reported to the traffic light controller. It works because the sensor is causally connected to its immediate environment.
When measuring, we often want information that is not causally connected to a sensor. We use a measuring instrument for that. And, in order to aquire data, we must first establish the causal connections between the instrument and what it is that we want to measure.
As an example, consider a traditional thermometer. The reading on the thermometer reports only the temperature of the thermometer itself. If I want to measure the temperature in the oven, I must first place the thermometer in the oven and then wait until the thermometer temperature adjusts to that of the oven. So there’s a procedure to follow when measuring the temperature of some item.
Similarly, the reading on an ordinary analog clock tells us only the position of the hands on that clock. In order to be able to use it to tell the time, we must make sure that it is causally connected to the time standard that is in effect. We typically do this by setting the clock, perhaps to a time announced on the radio.
To summarize, a sensor is useful in a static situation, where there are already causal connections between the sensor and what we want information about. Measuring is more versatile, and appropriate in a portable situation. In order to measure, we follow procedures (or behaviors) that connect the instrument to what we want to measure, and then we read the measurement once that causal connection has been temporarily established.
Most animals are mobile organisms. They do not have useful static connections. So they cannot rely on sensing. They need to use measurement to pick up useful information about their environments. That is to say, they must carry out procedures, or sequences of actions in the world, so as to enable them to establish the temporary causal connections needed for getting useful information.
People sometimes wonder what consciousness is for. Well, that’s what it is for. We need consciousness in order to setup suitable temporary causal connections, such as are needed to inform ourselves about the state of the environment.