I think ultimately 'materialism' simply means a belief, or a desire to believe, that the ordinary world of everyday perceptions is the only reality. This is why any argument against it is treated with such scorn: for those who accept this view, anything which challenges it is actually a threat to your identity and sense of who you are in the world.
An example is provided by ESP research. At the turn of the last century, labs were set up to discover whether such things really occur. J. B. Rhine and others spent years doing trials and amassing evidence. However at each juncture, materialism kept moving the goal-posts: the evidence must be tainted, the trials must be poorly designed, the interpretation must be faulty. In response to each of these complaints, the methodology was refined, more tests run, more data accumulated. The example given above is typical: it is true that remote viewing has been proven by the standards of ordinary science, but because we view it as an extraordinary claim, we will now demand 'extraordinary' evidence.
In 1955 George Price wrote that 'dozens of experimenters have obtained positive results in ESP experiments, and the mathematical procedures have been approved by leading statisticians'. Yet later in the same articles he writes that 'ESP is incompatible with scientific theory [and concludes] that many of them are dependent on clerical and statistical errors....'
This is typical of many of the so-called 'skeptics' discussed in Chris Carter's Parapsychology and the Skeptics, from which this quote is taken. There are dozens more examples.
What we're dealing with in all this is belief system
- an emotional attachment to a particular view of reality. It has nothing to do with science, as such. It is just an attitude towards existence.