In the book "The Call of the Wild", why was Buck's ability to steal food viewed by the author in a positive light?
The transition of Buck from obedient dog to wolf-pack leader implies a change of values and actions to cope with the changes in the environment. In the context of "civilized" society, theft is wrong, as it denies the property owner the use of his or her property, and "civilized" culture values property rights. What Jack London is showing here is a transition -- In the wilderness, property rights take a back seat to the supreme virtue of survival--and Buck learns to kill or steal to survive in Alaska, doing things he would never do in California. This suggests that survival in California is more or less a given--he had a house, master, and food--whereas in Alaska all those items had to be earned and fought for.
As an interesting corollary, consider the story of "Alive," where humans (not dogs!) had to consider their values in the light of an extremely harsh environment, and choose to engage in cannibalism to survive, rather than maintain their "civilized" values and perish.