A holistic detective is a detective using holistic detection to investigate and solve cases, which is based on the principle of the interconnectedness of all things. The profession was invented by Dirk Gently, who is its only practising follower with his Holistic Detective Agency.
Dirk Gently often tries to use this investigative principle to scam money out of his clients, but is surprised -- and often dismayed -- to find he actually arrives at the correct conclusions and solves the case.
A part of holistic detection is the method of Zen navigation.
In the lore of the 2016 Dirk Gently's Holistic Detective Agency series, holistic detection is a form of causality psychic trait of anomalous entities.
- "I'm very glad you asked me that, Mrs Rawlinson. The term 'holistic' refers to my conviction that what we are concerned with here is the fundamental interconnectedness of all things. I do not concern myself with such petty things as fingerprint powder, telltale pieces of pocket fluff and inane footprints. I see the solution to each problem as being detectable in the pattern and web of the whole. The connections between causes and effects are often much more subtle and complex than we with our rough and ready understanding of the physical world might naturally suppose." --Dirk Gently to a client, Dirk Gently's Holistic Detective Agency
- "Anyway, I am not as other private detectives. My methods are holistic and, in a very proper sense of the word, chaotic. I operate by investigating the fundamental interconnectedness of all things. Every particle in the universe affects every other particle, however faintly or obliquely. Everything interconnects with everything. The beating of a butterfly’s wings in China can affect the course of an Atlantic hurricane. If I could interrogate this table-leg in a way that made sense to me, or to the table-leg, then it could provide me with the answer to any question about the universe. I could ask anybody I liked, chosen entirely by chance, any random question I cared to think of, and their answer, or lack of it, would in some way bear upon the problem to which I am seeking a solution. It is only a question of knowing how to interpret it. Even you, whom I have met entirely by chance, probably know things that are vital to my investigation." --Dirk Gently to Sally Mills, The Long Dark Tea-Time of the Soul
- "Interconnectedness! Coincidence, and the rarer, sexier coinky-dinks. Once hired, I am intrinsically connected to the specific case. I then will eventually solve the mystery merely by just kind of doing whatever. [...] Everything is connected. Nothing is also connected." --Dirk Gently, Dirk Gently's Holistic Detective Agency (BBC America) Episode 1.01 Horizons