Lindsey buys an office building for $100,000. After properly deducting $20,000 in depreciation, she has the building appraised, and it is demonstrably worth $110,000 because the surrounding neighborhood is quickly gentrifying. That is to say, Lindsey's office building has appreciated to a value above her original purchase price so that she now owns economic wealth of $110,000 with respect to the building. (As an aside, you will learn that the fact that Lindsey's property has increased in value does not mean her depreciation deductions were improper. Stay tuned.) Unfortunately, shortly after the appraisal, the building burns to the ground, and she learns that (because she failed to make payments) her insurance coverage has lapsed. 

What is the amount of Lindsey's § 165 "loss" deduction? She clearly lost $110,000 of real economic value, but can she deduct that amount? Why or why not? See § 165(b).