[pantsdown]

I'm about halfway through reading harrington on holdem, this is the first book on poker I have read.

I noticed that when referring to a lot of his preflop hands he suggests folding/calling or folding/raising or folding/calling/raising in different percentages.

Now my question is why would you ever fold a hand randomly which you could also call. On page 185 for instance he says call KQo 50% of the time and fold 50%.

I understand you need to vary your play to make it harder for opponents to get a read, but if you fold they never see your hand, so your opponent might think that you are calling KQo 100%.

Wouldn't it make more sense to call 100% if you think you no one will raise, and fold 100% if you think someone will raise?