On the other hand, e.g. Descartes believed that animals were incapable of feeling pain (or anything at all) ― whatever signs of distress or anxiety they were sh

On the other hand, e.g. Descartes believed that animals were incapable of feeling pain (or anything at all) ― whatever signs of distress or anxiety they were showing were purely mechanistic phenomenons, with no innate state required for actual suffering behind those purely outward reactions. Well, that was back when animal physiology was only started being researched in the earnest; we today, on the other hand, have pretty comprehensive understanding of AI and cognitive processes overall so it's almost impossible for us to discover anything that'd require us to conclude that machines could, in fact, suffer just as humans ― how could they, if their computational substrate is so different from the humans'?