From the Guardian:
The reasons are twofold: science and necessity. First, neuroscience has demonstrated conclusively that there’s far more going on in the mind than the owners of those minds are generally aware. Mark Solms, a professor of neuropsychology and psychoanalyst who has pioneered much of the effort to test Freud’s findings against the neuroscientific, often points out that the conscious mind is capable of attending to six or seven things at once, while the rest of the nervous system is performing thousands. In that light, it seems perverse to deny that much of psychic life lies over the horizon of our awareness, doubly so when you consider experiences such as dreaming and slips of the tongue, or ordeals from infancy that can’t be remembered and yet demonstrably shape adult life.
We knew this:
The second reason that the unconscious is worth exploring has to do with medical necessity. Take the phenomenon of medically unexplained symptoms. These are widespread and everyday. In her recent book, It’s All in Your Head, neurologist Suzanne O’Sullivan reports that up to a third of people who go to the doctor have them. Their distress is real; the patient is not making it up. And yet no biological cause can be found. When you consider how much this costs – one 2005 study for such psychosomatic disorders estimates an annual cost of over $250bn in the US alone – it’s clear that any reasonable candidate for explanation should be investigated with urgency.
We didn’t know this:
The unconscious is one candidate, and conversion disorders provide a case in point. Also known as hysteria, these too are remarkably prevalent. All neurology clinics, for example, will have on their books many individuals with lives severely limited by seizures, but for whom an EEG reveals no epileptic activity in the brain. Other patients will be impaired by breathlessness, blindness, pain, paralysis. As O’Sullivan admits, even though there’s now technology to see inside the brain, the science is barely providing leads, let alone explanations.
But Freud’s central idea on conversion disorders – namely that a trauma, or perceived trauma, lies at the origin – is now routinely shown to have clinical efficacy. More.
See also: The human mind, the skinny
What great physicists have said about immateriality and consciousness