Controversy:

Many modern philosophers and social scientists either dispute the concept of an unconscious, or argue that it is not something that can be scientifically investigated or discussed rationally. In the social sciences, this view was first brought forward by John Watson, considered to be the first American behaviourist. Among philosophers, Karl Popper was one of Freud's most notable contemporary opponents. Popper claimed that Freud's theory of the unconscious was not falsifiable.

Still, many, perhaps most, psychologists and cognitive scientists agree that many things happen in our mind that we aren't conscious of.

John Watson criticizes the idea of an "unconscious mind," because he wanted scientists to focus on observable behaviors, seen from the outside, rather than on introspection. Karl Popper objected not so much to the idea that things happened in our minds that we are unconscious of; He objected to investigations of mind that were not falsifiable. If Freud could connect every imaginable experimental outcome with his theory of the unconscious mind, then no experiment can refute his theory.

The argument seems to be about how mind will be studied, not whether there is anything that happens unconsciously or not.

Questions about Unconscious mind:

The subconscious is not directly accessible to ordinary introspection, but it is capable of being "tapped" and "interpreted" by special methods and techniques such as random association, dream analysis, and verbal slips (commonly known as a Freudian slip), examined and conducted during psychotherapy. Thoughts, feelings and urges that are repressed are all present in the subconscious mind and "issues" need to be "worked out" with professionals skilled in the field of mental health and mental illness.

Is the unconscious altogether inaccessible, or is it just hard to access?

As some of the above examples indicate, material is constantly moving from the conscious mind to the unconscious and vice versa. The conscious mind only holds a small amount of information at any given time. In many cases information - especially easily accessible memories - can be called into awareness at will.

Some psychics also believe that the unconscious mind possesses a kind of "hidden energy" or "potential" that can realise dreams and thoughts, with minimal conscious effort or action from the individual. Some also believe that the subconscious has an "influencing power" in shaping one's destiny. All such claims, however have so far failed to stand scientific scrutiny.

Application of unconscious:

Knowledge of the unconscious has been exploited by marketing strategists employed by corporations to either play on hidden fears and secret desires buried in the common subconscious. Teams of psychologists are hired to do market research and understand the psychology of buying in order to use subliminal messages in advertising campaigns.