What does the dash mean?

Step One (page 58, Big Book) states:

"We admitted we were powerless over alcohol—that our lives had become unmanageable."

There are some popular misconceptions about this. First of all, we need to understand what unmanageability is not.

It's not generalised or pre-existing incompetence, neuroticism, disorganisation, or external chaos, distinct from the effects of drinking. Firstly, the Big Book nowhere glosses unmanageability as these; secondly, it's patently not true of all alcoholics; thirdly, plenty of non-alcoholics are these things; and fourthly, the poster boys, Jim (page 35) and Fred (page 39), do not fit this description except in as far as their drinking is directly causing these. If the Steps require such an admission, many alcoholics would be barred from continuing.

Bill explained unmanageability in the chapter Step One in Twelve Steps and Twelve Traditions:

Since Step One requires an admission that our lives have become unmanageable, how could people such as these take this Step? It was obviously necessary to raise the bottom the rest of us had hit to the point where it would hit them. By going back in our own drinking histories, we could show that years before we realized it we were out of control, that our drinking even then was no mere habit, that it was indeed the beginning of a fatal progression.

The person is powerless; the person's life is therefore unmanageable. We've lost control of drinking and therefore our lives. Unmanageability is not a second, additive condition. This relationship is one of entailment. If (a) is true, (b) is true. (a) entails (b). In US American English, an unspaced em dash conveys this relationship. In words, we could replace the dash with 'and so', 'and consequently', 'and thus' etc. Step One is not a cumulative test with two parts; it is a single test.

If I am powerless over alcohol (doomed to drink, doomed to drink too much), I am not in charge of my life: the rat-and-lizard brain is in charge, and unless it's knocked out by an intervening God, I'm toast.