Inglis in his book "The Hidden Power" (1986) invoked a conspiracy theory that established scientists have denied and suppressed evidence for the existence of a psi force. Inglis suggested that an underlying psi force could explain biological evolution, extrasensory perception, mediumship, psychokinesis, social behaviour of insects, religious experiences, telepathy amongst other mysteries. According to Inglis the untapped and untamed force sometimes works and sometimes doesn't, depending on the factors involved. Terry Hamblin gave the book a mixed review but criticized the book for endorsing spiritualistic activities such as ectoplasm and table tapping.