Blindsight and Echopraxia by Peter Watts
Blindsight (2006) and Echopraxia (2014) are two philosophically dense, science fiction novels that explore profound questions about consciousness, intelligence, and the nature of humanity.
Blindsight follows a crew of individuals with abnormal neurological conditions sent to make first contact with an alien intelligence, examining whether consciousness is truly necessary for intelligence.
Echopraxia is a "sidequel" that runs parallel to Blindsight, following a baseline human scientist caught between warring factions of posthumans like resurrected vampires and hyper-intelligent hive minds, delving into questions of free will, identity, and the illusion of human autonomy and choice.