Here is the grid of possibilities:
||A. "Today you'll be with me"
||B. "I tell you today"
|1. Isaiah speaks of despair
|2. Isaiah speaks of unconsciousness
To those seeking to avoid a contradiction, there are 2 ways out:
- Show that Isaiah speaks of despair
- Move the comma in Luke
(one could do both, but for purposes of resolving a contradiction it is unnecessary)
The infamous comma
Dottard has already made the case for adjusting the common location of the comma in the Lukan passage, and rightly points out that there was no punctuation in the original text.
I do not contest that both comma options are grammatically plausible. I do suggest, however, that it is relevant to consider the realities of writing without punctuation: if a writer wants the reader to understand, the writer must take care to avoid ambiguity.
One of the ways this is done is by using an introductory word or phrase, such as "behold" or "now" or "and it came to pass" -- in a world without punctuation, this tells the reader "we're now starting a new idea" (or a new sentence, in modern parlance). Luke clearly knows this and uses these phrases in his work.
If Luke wants the reader to understand that he's using the phrase "I say unto you today", he has failed to make it clear to the reader that this is what he is doing, rendering the word "today" entirely unnecessary. In fact, if this were Luke's intent, he would have been better off leaving out the word "today" entirely.
That said, no author avoids ambiguity completely, and Luke is known to make ambiguous statements elsewhere (Luke 2:2 being the classic example). Avoiding the contradiction by moving the comma is a possible solution, but not a definite solution.
Hezekiah had a rough day
The Isaiah passage in the OP is a psalm of praise from king Hezekiah, not a vision or sermon of Isaiah (see verse 9). That this is a psalm is further supported by the clear echoes Hezekiah makes of some of the psalms of his ancestor, David (see esp. Psalm 6:4-5 & 30:9).
I have written about these Psalms in the Addendum here. For a more thorough review & a reductive argument against post-mortal unconsciousness, see the linked post. For a quick summary:
This serves to highlight the temporal nature of David's concerns.
While his spirit is in Sheol, David will not be doing the things he's
doing now (in life) to praise God and teach His message. He sees an
end to his ability to do what God sent him (David) here to do.
In this Psalm, David is grateful to God for preserving his life on
earth and wants to praise & serve God on earth in gratitude.
The same can be said of Hezekiah's psalm in Isaiah.
It is noteworthy that both David & Hezekiah are kings who have a great deal of power & luxury from a worldly standpoint--they recognize that the privileged position they occupy won't follow them to Sheol. "Having it all" can create a variety of incentives, such as:
- Valuing the things of this life too much
- Defining one's identity by one's rank, power, or possessions
- Feeling an obligation to use one's gifts to accomplish good
Any combination of the feelings above can readily lead someone to resist or even fear death. What am I giving up? Did I really accomplish everything it was in my power to accomplish?
It is not even necessary to impute any negative motives to Hezekiah; he nearly died. It is clear that he, like David before him, wants to use his remaining time in life to praise God and "make known thy truth". He has a unique position here and now (from his perspective) to do both of those things to great effect.
Episode 37--the Assyrian Menace
Isaiah 38 is found in the "history" portion of Isaiah:
- The "Assyria" section (chapters 1-35)
- The history section (chapters 36-39)
- The "Babylon" section (chapters 40-66)
Isaiah doesn't follow the pattern with complete obstinance, but he's clearly organized his book by topic, and grouped major themes together. Chapter 38 is part of his account of some of the most significant political events of his (Isaiah's) life, including the war with Sennacherib.
Episode 37 of Isaiah has a very compelling plot line and keeps fans on the edge of their seats--the great potentate Sennacherib, having laid waste to city after city, civilization after civilization, brings his hordes to Jerusalem to conquer it as well. The stakes couldn't be higher (if Jerusalem had been destroyed by Assyria more than a century before it really fell to Babylon, we probably would have no Bible today).
Hezekiah is a righteous king who works with his advisors and prophets to save Jerusalem by hearkening to and trusting in the Lord. Hezekiah knows full well what Assyria has done to the Nothern Kingdom, and that it is his own kingdom (Judah) that is keeping alive the records of Israel and the faith in the God of their fathers.
The Lord preserves Judah, led by its righteous king, Hezekiah. Thus, Hezekiah's apprehension about death has a far more sweeping application. If he, Hezekiah, is not there to lead his people (righteously), what will become of them? What would have already become of them? (check out the compelling sequels Jeremiah and Lamentations to find out).
Hezekiah is rightly concerned--who will praise the Lord, thank Him, serve Him, and teach His words in future generations--if the covenant people are destroyed.
18 For Sheol does not thank you; death does not praise you; those who
go down to the pit do not hope for your faithfulness.
19 The living, the living, he thanks you, as I do this day; the father
makes known to the children your faithfulness.
Hezekiah--by serving & trusting the Lord--has preserved his people and their faith from meeting the same destructive fate as the Northern Kingdom. He is therefore worried for what will happen, not only to him, but to his people--and the subsequent generations that need to learn of God's faithfulness--if he (Hezekiah) is unable to finish the work he seeks to do in mortality.
Hezekiah looks at his close scrape with death, and he sees despair. He sees a chance to live longer and do more for God & his people, and he rejoices.
This puts us in row 1 of the grid at the top of the post. Regardless of the decision we make on the Lukan comma, row 1 has no contradiction.