Game theory and Decision theory are two approaches for our guidance in decision making. Game theory presupposes that there are at least two players with conflicting interests and the outcome of the game depends on the decisions of all the players, while the decision theory presumes that the decision of only one agent affects the outcome because the decision maker (group or individual) has to reckon with only a passive environment (i.e. he has no opponent). Now, if the environment is passive why are the outcomes of various actions uncertain? Adherents of decision theory claim that it is because the environment itself is impinged with uncertainties due to the presence of random processes which affect the environment unpredictably. Numerical probabilities may be assigned as measures of these uncertainties provided the process is regular and observable. E.G., if my problem is to decide whether or not to take a raincoat while going for a walk, I can assign, on the basis of past observed data, probability of its raining and hence getting wet and take a decision accordingly. It is the phenomenon of regularity which makes the environment passive. However, even with the most regular random phenomenon, we have rare happenings (it may rain even though the probability is very low) which are usually ignored as exceptions.