NOTE: THE CONVERGENCE OF FACT AND OPINION
Note that Rule 701 does not require a lay witness to limit himself to statements of fact, as opposed to statements of opinion or inference. The following excerpt from W. King and D. Pillinger, Opinion Evidence in Illinois 3-4 (1942), a book that was highly influential with the draftsmen, explains why.
When you look at the object on which you are sitting and say "chair" the sound "chair" is obviously not the object "chair." You can't sit on the noise "chair." The word is only your ... response to the pressure of the object on your buttocks and the light beams from the object upon your optic nerves when you look down at it. The word "chair" isn't the fact "chair."
You can perceive a simple thing like a chair in many aspects. You can see it as a piece of furniture constituting with other pieces the furnishings in your room, or as an article of wood and upholstering designed to accommodate a person in a sitting position. A close examination might disclose to the expert that it was a Grand Rapids chair made since 1910. A microscopic examination would disclose the cellular character of the material from which it was made and possibly the locality where that wood was grown, the age of the trees from which it was cut, and (if you were sufficiently interested) the particular tools which have been used in cutting it and which have left their marks upon it. In a sense, however, the ultimate reality of this chair is far beyond your perceptions even with a microscope. Submicroscopically, you know from what science has told you that this chair consists of a mad dance of electrons which you cannot see just as you cannot see the blades of your electric fan when it is running. But which of these various perceptions of the chair is The Fact? Obviously any one of them is just as much (and just as little) a fact as the others. Each of us sees different "facts" in everything we look at. We are surrounded by a world of objective reality which we call facts. But as soon as we try to translate any part of that world into language it ceases to be facts and becomes thoughts.
So, when our judge instructs the witness to state the facts it is as though we demanded that the witness fly by flapping his arms. The witness can't state facts and neither can the judge--facts are unspeakable and unstatable. We can't reproduce in language either reality or our perception of reality. All statements in language are statements of opinion, i.e., statements of mental processes or perceptions. So-called "statements of fact" are only more specific statements of opinion. What the judge means to say, when he asks the witness to state the facts, is: The nature of this case requires you to be more specific, if you can, in your description of what you saw.
Just how specific a judge should require a witness to be will depend greatly on how central the matter about which the witness is testifying is to the resolution of the case:
Ordinarily, in a law suit, you would be permitted to testify that this object was a chair. But if the suit were an action to collect a tax on chairs, if the kernel of the controversy was whether the object was a chair, your statement that this was a chair would be rejected as your opinion and you would be asked to "state the facts" regarding the object. In other words, the legal concept of what is a statement of fact and what is a statement of opinion varies with the issues in the case.
The rule, then, is meant to encourage witnesses to speak in a natural way at a level of specificity helpful to the factfinder. For example, witnesses anxious not to overstate their testimony often qualify what they are saying by adding, "I think" or "I believe." Does this indicate that their statements are impermissible opinions under Rule 701 or not based on first-hand knowledge as required by Rule 602? The question cannot be answered dogmatically. As the rule indicates, the judge must decide whether the witness is speaking from personal knowledge, and whether the testimony, as qualified, will be helpful. As Dean Ladd states:
Closely associated with expression of facts in terms of inference is the statement of facts as the impression of the witness. Illustrative of these expressions are, "I think," "I believe," "my impression is," "I cannot be positive, but I think," "to the best of my recollection," or "it is my understanding." The admissibility of testimony accompanied by such limitations involves the same fundamental issue to be considered when permitting the witness to testify in terms of inference, namely, is the witness speaking from his personal knowledge or is his testimony only a mental speculation. Not infrequently such precautionary statements may strengthen the testimony because they indicate that the witness does not want to overstate the facts. On the other hand, such statements may indicate that his recollection is poor which would weaken the testimony but not exclude it. Only when it appears that the witness has not personally perceived the matter about which he testifies will the testimony be excluded.
Ladd, Expert and Other Opinion Testimony, 40 Minn. L. Rev. 437, 440 (1956). See 3 Weinstein and Berger, Weinstein's Evidence 701-15 to 701-18 at ¶710 (1981).