We present a new approach for constructing debuggers based on declarative specification of bug conditions and root causes, and automatic generation of debugger code. We illustrate our approach on several classes of bugs, memory or otherwise. For each bug class, bug conditions and their root cause are specified declaratively, in First-order logic, using 1 to 4 predicates. We employ a low-level operational semantics and abstract traces to permit concise bug specification and prove soundness. To facilitate locating bugs, we introduce a new concept of value propagation chains that reduce programmer burden by narrowing the fault to a handful of executed instructions (1 to 16 in our experiments). We employ automatic translation to generate the debugger implementation, which runs on top of the Pin infrastructure. Experiments with using our system on 7 versions of 4 real-world programs show that our approach is expressive, effective at finding bugs and their causes, and efficient. We believe that, using our approach, other kinds of declaratively-specified, provably-correct, auto-generated debuggers can be constructed with little effort.