I'd like to come back to P.A.F.'s leading contention - that unions decrease the number of jobs available. I really will try to be civil, because though I might disagree, I certainly support anothers right to their different opinion.
I hope we can all agree that individuals are seen as choosing between two things which give (pardon economic parlance) utility : leisure and goods.
As goods can only be acquired through work and as, in this regard, time spent not at leisure is spent at work, it is clear that by analysing individuals' choices we will discover how many hours of work they wish to supply. Individuals will supply hours of labour up to the point where their marginal rates of substitution between leisure and goods are equal to their wage rate. The income and substitution effect of a wage-rate change make it impossible, a priori, to say which will be stronger. Therefore, we can say nothing about the effect on hours of work of a change in the wage rate. The Neoclassical Theory
The demand for labour is derived from the value of the goods and services it produces. An employer who is aiming to maximise profits will employ labour as long as the value of the goods produced by additional units of labour is greater than, or at the margin equal to, the cost of labour.
How does the profit maximising firm choose between the various alternative combinations of capital and labour which can produce any given output? It does so on the basis of the relative costs of labour and capital services.
In isolation - the demand for labour decreases as the wage rises and vice versa. However, labour markets do not operate in isolation. To assume that the price of capital services remain constant while wages change is rarely the case.
Conclusion - It can be seen that, on its own terms, marginal productivity theory provides a precise explanation of the demand for labour. It does not, however, purport to explain wages because for that we need to include supply factors as well.
All of this has been partially para-phrased and sometimes directly quoted from The Economics of Australian Labour Markets by Keith Norris
So back to you P.A.F. Do you still insist on your simplistic assertions?