Issue Tree

A big question like "why are sales down?" cannot be answered as posed; it has to be broken into parts. An issue tree decomposes one question top-down into a structured set of sub-questions, recursively, until the leaves are small enough to answer directly. The load-bearing constraint is MECE: at every branch the children must be Mutually Exclusive (no two overlap) and Collectively Exhaustive (together they cover the whole parent, with nothing important left outside). That discipline forces coverage, prevents double-counting, and makes the decomposition inspectable - a reader can challenge one branch instead of arguing a wall of prose. The output is an issue tree, not a discussion, and it restructures the question rather than answering it.

When to Use

• A question is too broad, ambiguous, or multi-cause to answer as posed ("why is churn rising?", "where is our margin leaking?", "should we launch a free tier?").
• Analysis must be split so work can be parallelized or prioritized across non-overlapping branches.
• Coverage matters: missing a whole category of cause or option would be costly, so collective-exhaustiveness has real value.
• Early in a diagnosis or strategy workflow, to turn an unanswerable prompt into a tractable set of answerable parts.

When NOT to Use

• The question is simple or already has an obvious structure. Decomposing a one-step question into a tree is overhead and false rigor.
• To evaluate whether a given argument or recommendation is sound. That is reasoning over an answer that already exists - use think-argument-mapping. An issue tree decomposes a question top-down before any answer exists; an argument map lays out the support and objections for an answer already on the table.
• To organize existing notes, findings, or observations bottom-up into themes. That is clustering from the data - use think-affinity-mapping. An issue tree imposes a top-down split before gathering; affinity mapping discovers structure from what is already gathered.
• As the answer. A clean tree restructures the question; it does not resolve it. Stopping at a pretty tree without driving the leaves to data or judgment is the central misuse.

Instructions