Intellectual black holes are belief systems that draw people in and hold them captive so they become willing slaves of claptrap. Belief in homeopathy, psychic powers, alien abductions – these are examples of intellectual black holes. As you approach them, you need to be on your guard because if you get sucked in, it can be extremely difficult to think your way clear again.
Stephen Law provides us with a field guide on how to avoid falling into these black holes of bullshit by recognizing the signs of intellectual dishonesty relied upon by those who promote them. In this question and answer article from New Scientist, Law explains more.