Thinking necessarily involves inference, but only part of an inferential statement is empirical.
Most of the information we have in our heads is based, not directly on observable fact, but on inference from fact. Thus, for example, when I see the cheese on the table and say, “Someone has put the cheese on the table.” I may not have seen the cheese being put on the table, but I infer that someone has put it there. The same is true when we see the wind blowing the trees through the window: we can see the trees moving and we infer that it is the wind that is moving them.
Inferential thinking consists of three elements. Let us look at these:
The first element is the sense data (e.g. The cheese is on the table) which we receive at least in part through our five senses (sight, sound, smell, touch, taste). But even what appears to be observable fact is a product of two parts only one of which is exclusively empirical: i.e. the external world that is impinging on our senses. But prior to our observation we also need concepts such as cheese, table and onness in our heads which we use to capture the sense data in the mind.
The second element in making an inference is a rule, either absolute or probabilistic, which we apply to the situation (e.g. Household objects are in the place they are because a human being has put them there). Rules may be necessarily true (e.g. All objects exist in space and time), or contingent and spring from repeated past experience (e.g. Fresh strawberries taste nice). In the case of contingent truths we assume that because something held true repeatedly in the past it will hold true in the future.
The third element is a conclusion drawn by means of logic from the observable fact and the rule; e.g (1) Household objects are in the place they are because a human being has put them there. (2) The cheese is on the table, so (3) a human being put the cheese on the table.
The key philosophical point to draw out of this analysis is that only part of an inference is empirical. The concepts, the rule, and the logic do not derive from our immediate observation, but are applied to it, and contain non-empirical elements. Thus, inferential statements are only in part empirical.