My question has two components:
Reasonableness. What does it mean for a position to be reasonable? What conditions does a position have to meet to be regarded as reasonable?
Physicalism. Wikipedia defines it as follows:
In philosophy, physicalism is the metaphysical thesis that "everything is physical", that there is "nothing over and above" the physical, or that everything supervenes on the physical. Physicalism is a form of ontological monism—a "one substance" view of the nature of reality as opposed to a "two-substance" (mind–body dualism) or "many-substance" (pluralism) view. Both the definition of "physical" and the meaning of physicalism have been debated.
Physicalism is closely related to materialism, and has evolved from materialism with advancements in the physical sciences in explaining observed phenomena. The terms "physicalism" and "materialism" are often used interchangeably, but can be distinguished based on their philosophical implications. Physicalism encompasses matter, but also energy, physical laws, space, time, structure, physical processes, information, state, and forces, among other things, as described by physics and other sciences, as part of the physical in a monistic sense. From a physicalist perspective, even abstract concepts such as mathematics, morality, consciousness, intentionality, and meaning are considered physical entities, although they may consist of a large ontological object and a causally complex structure.
Thus, non-physicalism can be understood as the thesis that physicalism is false, that is, the thesis that not everything is physical, or that there exists at least one thing that is not physical.
Is the belief in non-physicalism reasonable? How can someone reasonably conclude that physicalism is (probably) false? Is there any piece of data that might lend credence to the rejection of physicalism?
EDIT. Other suggested definitions of Physicalism:
Physicalism is, in slogan form, the thesis that everything is physical. The thesis is usually intended as a metaphysical thesis, parallel to the thesis attributed to the ancient Greek philosopher Thales, that everything is water, or the idealism of the 18th Century philosopher Berkeley, that everything is mental. The general idea is that the nature of the actual world (i.e. the universe and everything in it) conforms to a certain condition, the condition of being physical. Of course, physicalists don’t deny that the world might contain many items that at first glance don’t seem physical — items of a biological, or psychological, or moral, or social, or mathematical nature. But they insist nevertheless that at the end of the day such items are physical, or at least bear an important relation to the physical.
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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’ appears in English towards the end of the 17th century, 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. While it is not clear that Neurath and Carnap understood physicalism in the same way, 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.
‘Physicalism’ looks at the view that everything that exists today—including human minds—came about in virtue of the rearrangements of and interactions between the physical particles and forces that emerged after the universe’s birth. There are a number of different versions of physicalism: identity theory, functionalism, mysterianism, eliminativism, non-reductive physicalism, and emergentism. The concept of multiple realization allows for the same type of mental states to have different neural signatures and contrasts physicalism with panpsychism, the view that the fundamental components of the universe are conscious. Most physicalists maintain the strongest philosophical argument for physicalism, what has come to be known as ‘the causal argument for physicalism’.
Source: Physicalism | Philosophy of Mind: A Very Short Introduction | Oxford Academic

But by definition, non-physicalist beliefs are generally non-empirical- Are you suggesting that the non-physical aspects of reality (if they exist) cannot be experienced? Can you please share a link to the definition of physicalism you are referring to, that rules out the possibility of experiencing the non-physical? – Mark Mar 06 '24 at 16:11