Nazca lines

My response to a particle physicist on Facebook:

Brian Colquhoun 

Not really; that's just an argument from ignorance. Things boggle my mind every day. That makes the case that I don't understand something for whatever reason, and not that it points to some purpose.

Hays

Would you say the same thing about Nazca lines? These are puzzling because it's unclear how the artists are able to draw these patterns when they couldn't see the pattern from ground level. So should we infer that these are made by humans, or is that an argument from ignorance? Should we instead presume that these are natural patterns? 

Brian Colquhoun

There isn't any reason to suppose we're anything other than matter.

Hays

You mean, other than the hard problem of consciousness, precognition, psychokinesis, veridical apparitions, veridical NDEs, veridical OBEs, terminal lucidity, demonic possession, and John Lorber's hydrocephalic patients? There are multiple lines of evidence for substance dualism.

Brian Colquhoun

That doesn't necessarily mean that's definitely the case and can't be shown otherwise, but matter is all we know about.

Hays

Really? What about abstract objects, viz. numbers, logic, possible worlds? Even W. V. Quine resigned himself to being a "reluctant platonist". Likewise, Roger Penrose, although agnostic, is a mathematical realist.