I’ll straight up say that the answer is both. Some critics like to focus on a few statements (mostly from Martin Harris), instead of taking all statements into account, in order to say that the witnesses only had a spiritual vision. But that’s simply not true. Sure, Martin Harris said that he saw the plates with his spiritual eyes, but that’s because that is biblical language. In Christian theology, you can’t behold God without being translated. But this doesn’t mean they didn’t see the plates physically. In fact, the witnesses insisted that they saw the plates physically, ESPECIALLY Martin Harris. The following are a collection of quotes demonstrating this.
“Gentlemen, do you see that hand? Are you sure you see it? Are your eyes playing a trick or something? No. Well, as sure as you see my hand so sure did I see the angel and the plates.”
“It is not a mere belief, but is a matter of knowledge. I saw the plates and the inscriptions thereon. I saw the angel, and he showed them unto me.”
“Well, just as plain as you see that chopping block, I saw the plates; and sooner than I would deny it I would lay my head upon that chopping block and let you chop it off.”
“I know what I know. I have seen what I have seen, and I have heard what I have heard. I have seen the gold plates…An angel appeared to me and others.”
“The Prophet Joseph Smith, and Oliver Cowdery and David Whitmer and myself, went into a little grove to pray to obtain a promise that we should behold it with our natural eyes, that we could testify of it to the world.”
“In regards to my testimony to the visitation of the angel, who declared to us three witnesses that the Book of Mormon is true, I have this to say: Of course we were in the spirit when we had the view, for no man can behold the face of an angel, except in a spiritual view, but we were in the body also, and everything was as natural to us, as it is at any time.”
On one occasion, a skeptical military officer suggested, in David’s presence, that perhaps David had merely experienced some sort of hallucination. David, having none of this, drew himself up and declared,
“No sir! I was not under any hallucination, nor was I deceived! I saw with these eyes, and heard with these ears! I know whereof I speak!”
“It was a clear, open beautiful day, far from any inhabitants, in a remote field, at the time we saw the record, of which it has been spoken, brought and laid before us, by an angel, arrayed in glorious light, [who] ascend [descended I suppose] out of the midst of heaven. Now if this is human juggling—judge ye”
Martin Harris, quoted in “Statement of William M. Glenn to O. E. Fischbacher,” May 30, 1943, Cardston, Alberta, Canada, cited in Deseret News, October 2, 1943.
Martin Harris, quoted in Robert Aveson, “Three Witnesses to the Book of Mormon,” Deseret News, April 2, 1927.
Martin Harris, quoted in “Statement of Comfort Elizabeth Godfrey Flinders to N. B. Lundwall,” September 2, 1943, Ogden, Utah, cited in Assorted Gems of Priceless Value.
Martin Harris, quoted in “Affidavit of George Godfrey, October 29, 1921, original still held by attesting notary John J. Shumway, Garland, Utah.
Martin Harris Interview with Ole A. Jensen, July 1875 in Ole A. Jensen, “Testimony of Martin Harris (ONe of the Witnesses of the Book of Mormon),” undated (c. 1918), original in private possession, photocopies at Utah State Historical Society, LDS Church Archives, and Special Collections of BYU’s Harold B. Lee Library; cited in Dan Vogel (editor), Early Mormon Documents (Salt Lake City, Signature Books, 1996–2003), 5 vols, 2:375.
David Whitmer- Anthony Metcalf, Ten Years Before the Mast (Malad, Idaho: A. Metcalf, 1888), 74.
-Oliver Cowdery and Martin Harris, in letter dated 29 November 1829, quoted in Corenlius C. Blatchly, “THE NEW BIBLE, written on plates of Gold or Brass,” Gospel Luminary 2/49 (10 Dec. 1829): 194.