John P. McCaskey

Accounts of how the concept of temperature has evolved typically cast the story as ancillary to the history of the thermometer or the history of the concept of heat. But then, because the history of temperature is not treated as a subject in its own right, modern associations inadvertently get read back into the historical record. This essay attempts to lay down an authoritative record not of what people in the past thought about what we call ‘temperature’ but of what they thought about what they called ‘temperature’ (or one of its cognates), from medieval times to today. I find that invention of the thermometer had little impact on the concept of temperature. Much more significant were Fahrenheit’s invention of a reliable instrument and William Thomson’s effort to make a degree of temperature a unit of measure. Overlapping definitions of temperature then emerged in the late nineteenth century, and twentieth-century scientific developments forced physicists to reconsider temperature’s conceptual boundaries. It turns out that the concept of temperature has evolved through stages that correspond to four increasingly sophisticated types of measurement. Its maturation and its maturity shed light on the philosophy of conceptual change.

I lay out and examine two sharply conflicting interpretations of Aristotle's claims about nous in the De Anima (DA). On the human separability approach, Aristotle is taken to have identified reasons for thinking that the intellect can, in some way, exist on its own. On the naturalist approach, the soul, including intellectual soul, is inseparable from the body of which it is the form. I discuss how proponents of each approach deal with the key texts from the DA, focusing on four of the most important and interesting topics in this area. Two of these topics concern the activity of understanding (noêsis): first, what does Aristotle mean when he claims that the intellect cannot have a bodily organ and, secondly, what role does Aristotle think phantasmata (“images” or “representations”) play in understanding something? Two of the topics concern DA 3.5, one of the most difficult passages in Aristotle's corpus: first, what is the nature and role of the productive intellect (nous poiêtikos) introduced there and, secondly, what are this chapter's implications for the question of whether the intellect or intellectual soul can exist apart from the body? I conclude by identifying areas where further research is necessary