What is the difference between descriptive, analytical, persuasive and critical writing?
The simplest type of academic writing is descriptive, and its purpose is to provide facts or information. An example would be a summary of an article or a report of the results of an experiment. The kinds of assignment instructions for a purely descriptive assignment could be, e.g. identify, report, list, name, record, summarise, collect, define, etc.
However, it is rare for a university-level text to be purely descriptive. Most academic writing is also analytical. Analytical writing includes descriptive writing (i.e. facts or information), plus the added feature of re-organisation. That is, in analytical writing you not only give information, but you also re-organise it into categories, groups, parts, types or relationships. Sometimes, these are categories or relationships which are already part of the discipline (e.g. In the discipline of Law, there are 2 types of law: common law and statute law). Sometimes, these are categories or relationships which you create specifically for your text (e.g. If you are comparing two theories, you might break your comparison into 3 parts, based on 3 aspects of the theories, such as: how each theory deals with social context, how each theory deals with language learning, and how each theory can be used in practice). The kinds of instructions for an analytical assignment could be, e.g. analyse, compare, contrast, relate, examine, classify, etc.
In most academic writing, you are required to go at least one step further than analytical writing, to persuasive writing. Persuasive writing has all the features of analytical writing (i.e. information, plus re-organisation of the information) plus the added feature of your own point of view. Your point of view may be, for example, an interpretation of the findings, an argument or some recommendations. Most essays are persuasive, and there is a persuasive element in at least the discussion and conclusion of a research article. In persuasive writing, each claim that you make needs to be supported by some evidence – e.g. by a reference to an authoritative published source, by empirical findings or by original reasoning – whatever kind of evidence is appropriate for your discipline and the specific text you are writing. The kinds of instructions for a persuasive assignment could be, e.g. argue, evaluate, discuss, take a position; as well as evaluative language such as, e.g. more convincing, problem, opportunity, succeed, should.
Critical writing is common for research, postgraduate and advanced undergraduate writing. Critical writing has all the features of persuasive writing (i.e. facts + re-organised + your point of view), plus the added feature of at least one other point of view. That is, while persuasive writing requires you to have your own point of view on an issue or topic, critical writing requires you to consider at least two points of view, including your own. For example, you may explain a researcher's interpretation or argument, and then evaluate the merits of her argument, or give your own alternative interpretation. Examples of critical writing assignments include a critique of a journal article, or a literature review which finds the strengths and weaknesses of existing research. The kinds of instructions which can show that you are required to write critically could be, e.g. critique, debate, disagree, evaluate, etc. Usually these are accompanied by either the name of someone whose work you should critique (e.g. Chomsky (1975)) or else more general words for people’s opinions in the discipline, e.g. 'adherents of M-Theory', 'some may assume that…', 'qualitative versus quantitative approaches', 'those in working in the constructivist tradition', etc.
Many academic texts that you write will have some parts which are more analytical or descriptive, and other parts which are persuasive or critical. For example, an empirical thesis needs critical writing in the literature review, to show where there is a gap or opportunity in the existing research. However, the methods section will have many paragraphs which are mostly descriptive, in order to summarise the methods used to collect and analyse information. In the results section of an empirical thesis or a research report, there will be mostly descriptive and analytical writing, while the discussion section is more analytical, as you relate your findings back to your research questions, and generally also more persuasive, as you propose your interpretations of the findings.
Each of the types of writing above has specific language features. By developing your skill in these language features, e.g. by attending a workshop on critical writing (see links on the right), you can control how analytical, persuasive or critical your writing is.