What inner authority is
Human Design gives every chart two tools for decisions. The strategy comes from the type and says how to meet life: to respond, to wait for an invitation, to inform. The inner authority says how to know your own answer once a choice is in front of you. The system is clear that the mind is not an authority: thinking is useful for considering, comparing and advising others, but the decision is meant to come from the body.
How it is decided
Authority follows your defined centers in a fixed order of precedence, and the first one your chart allows is yours. A defined Solar Plexus outranks everything, because its emotional wave colors every other awareness. Without it, a defined Sacral gives sacral authority; without either, a defined Spleen gives splenic authority. Next comes the Heart, as ego authority: manifested when the Heart reaches the Throat, as in a Manifestor, and projected when it joins the G, as in a Projector. A G center joined to the Throat gives self-projected authority. Charts defined only in the Head, the Ajna and the Throat have mental authority, sometimes called no inner authority, and Reflectors, with no center defined, have lunar authority.
How common each one is
On 10,000 birth moments spread evenly over 1950 to 2009, 52% of charts have emotional authority, 33% sacral and 9% splenic. The rest are rare: self-projected 2.5%, mental 1.9%, lunar 0.9%, ego manifested 0.8% and ego projected 0.4%. Emotional authority is so common because the Solar Plexus has seven gates and seven channels, three of them to the Root alone, and any one of them defines it.
Authority and strategy together
The two work in sequence: the strategy says when a choice is really in front of you, and the authority gives the answer. A Generator waits for something to respond to, then listens for the gut's yes or no; if that Generator also has a defined Solar Plexus, the answer is trusted only once the feeling has settled over time. A Projector waits for an invitation, then uses authority to decide whether to accept it. A Manifestor informs the people affected before acting, once authority has said yes.
Living with it
The tradition presents authority as something to test in small decisions before trusting it with big ones. For emotional authority that means noticing how a choice feels over several days; for sacral authority, answering yes-or-no questions out loud; for splenic, catching the first quiet knowing. The free Human Design chart calculator gives your authority with the centers that decide it.