I suggest reading the following quote:
"Physicalism is sometimes known as ‘materialism’. Indeed, on one strand to contemporary usage, the terms ‘physicalism’ and ‘materialism’ are interchangeable. But the two terms have very different histories. The word ‘materialism’ is very old, but the word ‘physicalism’ was introduced into philosophy only in the 1930s by Otto Neurath (1931) and Rudolf Carnap (1959/1932), both of whom were key members of the Vienna Circle, a group of philosophers, scientists and mathematicians active in Vienna prior to World War II. It is not clear that Neurath and Carnap understood physicalism in the same way, but one thesis often attributed to them (e.g. in Hempel 1949) is the linguistic thesis that every statement is synonymous with (i.e. is equivalent in meaning with) some physical statement. But materialism as traditionally construed is not a linguistic thesis at all; rather it is a metaphysical thesis in the sense that it tells us about the nature of the world. At least for the positivists, therefore, there was a clear reason for distinguishing physicalism (a linguistic thesis) from materialism (a metaphysical thesis). Moreover, this reason was compounded by the fact that, according to official positivist doctrine, metaphysics is nonsense. Since the 1930s, however, the positivist philosophy that under-girded this distinction has for the most part been rejected—for example, physicalism is not a linguistic thesis for contemporary philosophers—and this is one reason why the words ‘materialism’ and ‘physicalism’ are now often interpreted as interchangeable.
Some philosophers suggest that ‘physicalism’ is distinct from ‘materialism’ for a reason quite unrelated to the one emphasized by Neurath and Carnap. As the name suggests, materialists historically held that everything was matter — where matter was conceived as “an inert, senseless substance, in which extension, figure, and motion do actually subsist” (Berkeley, Principles of Human Knowledge, par. 9). But physics itself has shown that not everything is matter in this sense; for example, forces such as gravity are physical but it is not clear that they are material in the traditional sense (Lange 1865, Dijksterhuis 1961, Yolton 1983). So it is tempting to use ‘physicalism’ to distance oneself from what seems a historically important but no longer scientifically relevant thesis of materialism, and related to this, to emphasize a connection to physics and the physical sciences. However, while physicalism is certainly unusual among metaphysical doctrines in being associated with a commitment both to the sciences and to a particular branch of science, namely physics, it is not clear that this is a good reason for calling it ‘physicalism’ rather than ‘materialism.’ For one thing, many contemporary physicalists do in fact use the word ‘materialism’ to describe their doctrine (e.g. Smart 1963). Moreover, while ‘physicalism’ is no doubt related to ‘physics’ it is also related to ‘physical object’ and this in turn is very closely connected with ‘material object’, and via that, with ‘matter.’
In this entry, I will adopt the policy of using both terms interchangeably, though I will typically refer to the thesis we will discuss as ‘physicalism’. It is important to note, though, that physicalism (i.e. materialism) is associated with a number of other metaphysical and methodological doctrines. We will return to some of these when we discuss
Physicalism and the Physicalist World-picture."
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Physicalism (Stanford Encyclopedia of Philosophy)
