Read this and answer the question. If the question is unanswerable, say "unanswerable".

The materialist view is perhaps best understood in its opposition to the doctrines of immaterial substance applied to the mind historically, famously by René Descartes. However, by itself materialism says nothing about how material substance should be characterized. In practice, it is frequently assimilated to one variety of physicalism or another.

Was René Descartes an idealist or a materialist?
materialist