Can we ever know what it’s like to be a bat? Tra­di­tional du­al­ism, with its im­ma­te­rial souls freely float­ing around vi­o­lat­ing phys­i­cal laws, may be false; but what about the weaker the­sis, that con­scious­ness is a “fur­ther fact” not fully ex­plain­able by the phys­i­cal facts? A num­ber of philoso­phers and sci­en­tists have found this line of rea­son­ing per­sua­sive. If we feel this ar­gu­ment’s in­tu­itive force, should we grant its con­clu­sion and ditch phys­i­cal­ism?

We cer­tainly shouldn’t re­ject it just be­cause it sounds strange or feels vaguely un­scien­tific. But how does the ar­gu­ment stand up to a tech­ni­cal un­der­stand­ing of how ex­pla­na­tion and be­lief work? Are there any hints we can take from the his­tory of sci­ence, or from our un­der­stand­ing of the phys­i­cal mechanisms un­der­ly­ing ev­i­dence? This is the ques­tion that this se­quence will at­tempt to an­swer.