Do you know how psychiatrists or clinical psychologists diagnose depression? Have you read the DSM? Do you know how they come up with the criteria for psychiatric disorders in DSM? Do you know the controversies behind DSM? Do you know few decades ago homosexuality was regarded as a mental disorder? Do you know that there are researchers who want to introduce a new "psychiatric disorder" (i.e., hypersexual disorder) in the next edition of DSM for people who have sex more than 7 times a week ?

Here is the criteria for major depression: Diagnostic criteria:

Depressed mood and/or loss of interest or pleasure in life activities for at least 2 weeks and at least five of the following symptoms that cause clinically significant impairment in social, work, or other important areas of functioning almost every day

1. Depressed mood most of the day.

2. Diminished interest or pleasure in all or most activities.

3. Significant unintentional weight loss or gain.

4. Insomnia or sleeping too much.

5. Agitation or psychomotor retardation noticed by others.

6. Fatigue or loss of energy.

7. Feelings of worthlessness or excessive guilt.

8. Diminished ability to think or concentrate, or indecisiveness.

9. Recurrent thoughts of death (APA, 2000, p. 356).

I am sure everyone has met some of its criteria at some point in their life. Without a real diagnosis, you really can't say if the person has a major depression. Even with a diagnosis, how do you know the doctor is making the right diagnosis with SUCH VAGUE criteria?

Edit: I am very aware of what DanBC has pointed out about the other criteria: i) at least 2 weeks ii) and at least five of the following symptoms iii) clinically significant impairment in social, work, or other important areas of functioning almost every day.

BUT THEN, the question becomes "Why 2 week?" "Why at least five of the symptoms?" Who came up with the numbers? Let me tell you, the DSM committee have a lot of disagreement about those. Those numbers are not some magic numbers that once you pass that threshold, you suddenly become clinical depressed.