ARE "IS" AND "OUGHT" STATEMENTS DIFFERENT?
Keith Burgess Jackson has a thoroughly admirable account of what ideology does and how he himself escaped from it here. He makes some basic points about argument there that cannot be repeated too often. He shows by example what clear thinking on political matters is like and I found his article a joy to read. So how's that for a recommendation?
To my knowledge, however, there have never been two philosophers who agree on absolutely everything so I do have a quibble about one point he makes. He relies at one point on David Hume's famous contention that there is an unbridgeable gap between "is" and "ought" statements -- so that you cannot justify "ought" statements by "is" statements. Yet that is precisely what people normally do. An "ought" statement always commends some course of action and when people ask WHY that course of action is commended the reply is often in terms of "is" (empirical) statements (e.g. the commendation of X can be explained as: "X leads to generally desired consequences" or "X leads to consequences that you would like" or "I like X" or "X is the prevailing rule in this culture"). So in my view the fact that an "ought" statement can be explained in that way shows that it is an empirical statement to begin with. Statements in general have all sorts of influences on people (for example, if someone said to me: "Your son has just died", it is clearly an empirical statement but it would also have an enormous influence on me if true. It would cause me to take many actions that I would not otherwise take) and an "ought" statement is an empirical statement with what is expected to be one particular sort of influence -- a commendatory influence. So an "ought" statement is often simply a shorthand (compressed) "is" statement that can be promptly expanded if desired.
As I have shown here, however, "ought" statements are used in a variety of ways rather than in one single way. They always commend but they are not always empirical statements. Sometimes they are in fact very incoherent statements (at best pseudo-empirical statements) and I think Hume's difficulty arose out of a determination to find meaning in incoherent uses of "ought" statements (i.e. when "ought" statements are elaborated as being or emanating from timeless and universal rules that are "known" only in some mysterious and untestable way -- typically expressed by saying "X just IS right", with no further explanation given) and I simply regard that quest as a fool's errand. The world is awash with incoherent gibberish and baseless assertions so there is no reason to be either disturbed by it or interested in it when such assertions occur in moral discourse. When I encounter it, my usual response is to point out its incoherence and untestability and then refuse to have any further truck with such things (as I did here). I expand a little further on my view of what "ought" (moral) statements do here
Being primarily a psychologist, I am of course interested in WHY what I have called incoherent uses of moral terminology arise and I find the explanation given by philosophical psychologist John Maze persuasive: That they are a conscious or unconscious attempt at fraud -- an attempt to persuade by saying that immutable and peculiarly moral properties exist and that they have some claim on us because of that. Maze's work is not online but if you have access to a university library, you can find it in: Maze, J. (1973) "The concept of attitude". Inquiry, 16, 168-205. Maze also had a book published in 1983 called The Meaning of Behaviour which I have not read but which almost certainly would contain similar arguments.