<p>It doesn't. A decreasing and convex isoquant curve reflects a decreasing marginal rate of technical substitution (MRTS), not diminishing marginal returns.</p>

CC BY-SA 4.0
2024-10-18T00:01:50.543Z
but the change in the values of the MRTS as we go along the slope is due to DMR .The same way as the change in values MRS for the indifference curves is due to DMU ,according to my lecturer .
j jose
CC BY-SA 4.0
2024-10-18T10:23:12.587Z
@jjose No, it's not. Look at the production function $Y=(K+L)^a$. The marginal returns of $K$ (or $L$) are decreasing for $a<1$, constant for $a=1$, and increasing for $a>1$. But the MRTS $=1$ for all $a$. Similarily, a diminishing MRS is not due to DMU. Actually, the concept of DMU doesn't even make sense for ordinal utility functions as used in consumer choice problems.
VARulle
CC BY-SA 4.0
2024-10-16T09:45:45.680Z
2024-10-16T09:45:45.680Z
VARulle
<p>The layman explanation would be that the slope represents the rate of change of the curve, or in economics terms, the substitution of one input for the other in order to still end up with the same amount of output. Take any isoquant curve u see off google search, imagine the Y-axis is capital, the X-axis is labor. Then when u go from the extreme end of Y-axis (where the Y-coordinate of the curve is the highest), towards the extreme end of X-axis, you would realize that the graph would go from steep to shallow. Basically what this means is that the amount of units of X to make up for Y increases increases from left to right, and vice versa. This demonstrates the &quot;diminishing returns&quot; in input substitution.</p>

CC BY-SA 4.0
2024-10-16T06:45:12.167Z
2024-10-16T06:45:12.167Z
Economic-Theory
<p>so interms of simple mathematical explaination,when you double differentiate a productive function with respect to the variable you will get the value to be negative for the isoquant line which tells us that the isoquants have diminishing marginal value.</p>

CC BY-SA 4.0
2024-10-16T00:24:48.330Z
so you are saying when you double differentiate the isoquant function you will get negative values ?
j jose
CC BY-SA 4.0
2024-10-22T16:01:49.487Z
@jjose: This answer is wrong. You should instead examine the sign of the second-order derivative $\frac{\partial^2 K}{\partial L^2}$ holding production level constant.
Herr K.
CC BY-SA 4.0
2024-10-15T15:00:52.843Z
2024-10-15T15:00:52.843Z
Open Critic
<p>When learning about diminishing marginal returns we kept capital at a constant level usually and then we varied labour and with this, we can see the effects of diminishing marginal returns . We could also apply the same theory if we kept labour constant and capital variable, but this is less practical of an example as this wouldn't happen in real life.</p>
<p>However, my confusion about the isoquant curve (assuming it's not a perfect substitute or compliment) is how its sloping nature reflects the concept of diminishing marginal returns. As capital and labour both vary on a single isoquant curve, I can't think about diminishing marginal return unless either capital or at least labour is fixed and the other factor is variable. My only reasonable answer is that as we move to the extremes of the isoquant curve we are approaching a single value which we can parallel to the argument of keeping capital fixed and labour variable. But I don't think this is a good intuitive or even the actuall explanation for how DMR makes the isoquant slope. Could someone provide a better answer (I'm a first-year econ student)</p>

<marginal>
How does the slope of the isoquant curve reflect diminishing marginal returns
j jose
# How does the slope of the isoquant curve reflect diminishing marginal returns

(Asked by: username_0 on 2024-10-14)

When learning about diminishing marginal returns we kept capital at a constant level usually and then we varied labour and with this, we can see the effects of diminishing marginal returns . We could also apply the same theory if we kept labour constant and capital variable, but this is less practical of an example as this wouldn't happen in real life.

However, my confusion about the isoquant curve (assuming it's not a perfect substitute or compliment) is how its sloping nature reflects the concept of diminishing marginal returns. As capital and labour both vary on a single isoquant curve, I can't think about diminishing marginal return unless either capital or at least labour is fixed and the other factor is variable. My only reasonable answer is that as we move to the extremes of the isoquant curve we are approaching a single value which we can parallel to the argument of keeping capital fixed and labour variable. But I don't think this is a good intuitive or even the actuall explanation for how DMR makes the isoquant slope. Could someone provide a better answer (I'm a first-year econ student)

**Tags:** marginal

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## 3 answers

### Answer by username_1 on 2024-10-16. Score: 1

It doesn't. A decreasing and convex isoquant curve reflects a decreasing marginal rate of technical substitution (MRTS), not diminishing marginal returns.

> **Comments:**
> **username_0**: but the change in the values of the MRTS as we go along the slope is due to DMR .The same way as the change in values MRS for the indifference curves is due to DMU ,according to my lecturer .  
> **username_1**: @jjose No, it's not. Look at the production function $Y=(K+L)^a$. The marginal returns of $K$ (or $L$) are decreasing for $a<1$, constant for $a=1$, and increasing for $a>1$. But the MRTS $=1$ for all $a$. Similarily, a diminishing MRS is not due to DMU. Actually, the concept of DMU doesn't even make sense for ordinal utility functions as used in consumer choice problems.  

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### Answer by username_2 on 2024-10-16. Score: 0

The layman explanation would be that the slope represents the rate of change of the curve, or in economics terms, the substitution of one input for the other in order to still end up with the same amount of output. Take any isoquant curve u see off google search, imagine the Y-axis is capital, the X-axis is labor. Then when u go from the extreme end of Y-axis (where the Y-coordinate of the curve is the highest), towards the extreme end of X-axis, you would realize that the graph would go from steep to shallow. Basically what this means is that the amount of units of X to make up for Y increases increases from left to right, and vice versa. This demonstrates the "diminishing returns" in input substitution.


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### Answer by username_3 on 2024-10-15. Score: -1

so interms of simple mathematical explaination,when you double differentiate a productive function with respect to the variable you will get the value to be negative for the isoquant line which tells us that the isoquants have diminishing marginal value.

> **Comments:**
> **username_0**: so you are saying when you double differentiate the isoquant function you will get negative values ?  
> **username_4**: @jjose: This answer is wrong. You should instead examine the sign of the second-order derivative $\frac{\partial^2 K}{\partial L^2}$ holding production level constant.  

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