In medical ethics a distinction is commonly made between negative and positive autonomy. One’s negative autonomy is exercised in refusing medical care or refusing some specific treatment. Positive autonomy is the right to choose a specific treatment (within what is available and allowed). Expressing a preference for not being informed about some medical condition seems to exercise negative autonomy.
Several criteria define the autonomy of a person in medical ethics, including knowledge. The knowledge a person has is not simply derived from the quantity of information made available, but by the real information that the subject is able to understand and use in the assessment. It can be said, then, that under this perspective, the more knowledge one has the more autonomous one is.
To illustrate the role of knowledge in autonomy, consider two couples with a family history of genetic diseases. In both cases the woman is pregnant. Couple 1 doesn’t want to make any genetic test, because “whatever the result we would never consider abortion an option.” Couple 1 has a set of values that is not compatible with abortion. Couple 2 has the same values and does not consider abortion as a feasible option. Nonetheless, couple 2 chooses genetic testing and the result of the test is a very high likelihood of an impaired offspring. Though knowing this, couple 2 decides to have the baby too.
The decision (to have the baby) of couple 1 and couple 2 is the same, but is reached through different paths. Couple 1 didn’t wish to know, it exercised a kind of negative autonomy. Couple 2 exerted a kind of positive autonomy deciding to gain knowledge about the condition (actual or likely) of its offspring. They displayed different attitudes toward knowledge, but both made a kind of autonomous choice. Couple 1 didn’t want to test its offspring, and one may be tempted to say that it didn’t put its values to test in the light of knowledge possible to attain, whereas couple 2 in testing its offspring also gauged the strength of the values on the basis of which they made their decision.
I would say that the couples’ first choices to know/not to know are equally autonomous. Henceforth, however, the couples’ paths diverge and couple 2’s final decision (to have the baby) is a more autonomous one, because it uses more relevant knowledge. Couple 1’s preference for negative autonomy (not to know) leads, on this account, to a less autonomous final decision (to have the baby).