So the arguments:
f. All radicals are anti-corporate. Lucy is a radical. Therefore, Lucy is anti-corporate.
b. All softmicro products are junk, and FrontSheet is a softmicro product, so FrontSheet is junk.
Have the same underlying form:
All A are B. x is A. Therefore, x is B.
This is a valid form for an argument.
The invalid argument, (d), presented above, has the form:
x is A. y is A. Therefore x is y.
Another important form is
If P then Q. P. Therefore, Q.
An example of this form, from our friends the economists, is:
If inflation is to be fought at all costs, then unemployment must be maintained at a high level. Inflation must be fought at all costs. Unemployment must be kept high.