I know this is a silly question, my instructions are as follows; Decrease 1 stitch at each end of next and every following alternating row. Am I to assume that I am to decrease on a knit row and then on the purl row?
No, your question is not silly at all. I'm glad you asked. Alternating row refers to every other row. We see this type instructions a lot when working with bilateral decreasing and increasing sleeves or neck lines.
"Decrease 1 stitch at each end of next and every following alternating row" refers to decreasing 1 st at each end of the next row (usually the right side row). Then work the next row (usually the wrong side row) without decreasing. Then on the next right side row, you would do another decrease on each end again. Continue working this way until you meet the pattern requirement.
I hope my answer helps you with your question. Thank you for writing in.