Impact Factors: What is it doing to science

We are witnessing an exponential growth of scientific literature in recent times. “Documentary chaos” is what Samuel C. Bradford, the former librarian of the Science Museum in London said is happening in the field of scientific literature, referring to its exponential growth. But the assessment of scientific quality is a very difficult task. The general trend was to use paper counts, importance of the journal etc. But in the past three decades Impact factors and citation indices are being used at the international level.
So what is impact factor?
The impact factor for a journal is calculated by dividing the number of current citations to articles published in that journal in the two previous years by the total number of articles published in the journal in the two previous years.
Impact factors judges the journal more effectively than the contributor or author but it is also wrong to say that scientific content has a secondary role to play; in fact it is the classical chicken or the egg story. An author selects high impact journal for his/her contribution and in turn the contribution is what increases the impact factor of the journal - a vicious circle of sorts. Journals have reputation, but their stature is only derived from the usefulness of the articles they publish. Evaluation of journals is a formidable but indispensable task considering the wide range of choices available, but again arbitrary evaluation of scientists based on the prestige of journals is moot point.