Why idex scan not used?

=> create table t(id int4 primary key);
=> explain select min(id) from t;
NOTICE:  QUERY PLAN:
Aggregate  (cost=43.00 rows=1000 width=4)
  ->  Seq Scan on t  (cost=43.00 rows=1000 width=4)
EXPLAIN

Is it possible to make postgresql to use index scan when it calculate
MIN(id).